Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

622 files changed, 15359 insertions, 0 deletions

diff --git a/src/test/ui/type-alias-enum-variants/enum-variant-generic-args-pass.rs b/src/test/ui/type-alias-enum-variants/enum-variant-generic-args-pass.rs
new file mode 100644
index 000000000..0aa644db0
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/enum-variant-generic-args-pass.rs
@@ -0,0 +1,59 @@
+// run-pass
+
+// Check that resolving, in the value namespace, to an `enum` variant
+// through a type alias is well behaved in the presence of generics.
+// We check for situations with:
+// 1. a generic type `Alias<T>`, we can type-apply `Alias` when referring to a variant.
+// 2. a monotype `AliasFixed` of generic `Enum<T>`, we can refer to variants
+//    and the type-application of `T` in `AliasFixed` is kept.
+
+#![allow(irrefutable_let_patterns)]
+
+enum Enum<T> { TSVariant(#[allow(unused_tuple_struct_fields)] T), SVariant { _v: T }, UVariant }
+type Alias<T> = Enum<T>;
+type AliasFixed = Enum<()>;
+
+macro_rules! is_variant {
+    (TSVariant, $expr:expr) => (is_variant!(@check TSVariant, (_), $expr));
+    (SVariant, $expr:expr) => (is_variant!(@check SVariant, { _v: _ }, $expr));
+    (UVariant, $expr:expr) => (is_variant!(@check UVariant, {}, $expr));
+    (@check $variant:ident, $matcher:tt, $expr:expr) => (
+        assert!(if let Enum::$variant::<()> $matcher = $expr { true } else { false },
+                "expr does not have correct type");
+    );
+}
+
+fn main() {
+    // Tuple struct variant
+
+    is_variant!(TSVariant, Enum::TSVariant(()));
+    is_variant!(TSVariant, Enum::TSVariant::<()>(()));
+    is_variant!(TSVariant, Enum::<()>::TSVariant(()));
+
+    is_variant!(TSVariant, Alias::TSVariant(()));
+    is_variant!(TSVariant, Alias::<()>::TSVariant(()));
+
+    is_variant!(TSVariant, AliasFixed::TSVariant(()));
+
+    // Struct variant
+
+    is_variant!(SVariant, Enum::SVariant { _v: () });
+    is_variant!(SVariant, Enum::SVariant::<()> { _v: () });
+    is_variant!(SVariant, Enum::<()>::SVariant { _v: () });
+
+    is_variant!(SVariant, Alias::SVariant { _v: () });
+    is_variant!(SVariant, Alias::<()>::SVariant { _v: () });
+
+    is_variant!(SVariant, AliasFixed::SVariant { _v: () });
+
+    // Unit variant
+
+    is_variant!(UVariant, Enum::UVariant);
+    is_variant!(UVariant, Enum::UVariant::<()>);
+    is_variant!(UVariant, Enum::<()>::UVariant);
+
+    is_variant!(UVariant, Alias::UVariant);
+    is_variant!(UVariant, Alias::<()>::UVariant);
+
+    is_variant!(UVariant, AliasFixed::UVariant);
+}
diff --git a/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.rs b/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.rs
new file mode 100644
index 000000000..0031a4665
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.rs
@@ -0,0 +1,105 @@
+// Checks that applied type arguments of enums, and aliases to them, are respected.
+// For example, `Self` is never a type constructor. Therefore, no types can be applied to it.
+//
+// We also check that the variant to an type-aliased enum cannot be type applied whether
+// that alias is generic or monomorphic.
+
+enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
+type Alias<T> = Enum<T>;
+type AliasFixed = Enum<()>;
+
+impl<T> Enum<T> {
+    fn ts_variant() {
+        Self::TSVariant(());
+        //~^ ERROR mismatched types [E0308]
+        Self::TSVariant::<()>(());
+        //~^ ERROR type arguments are not allowed on this type [E0109]
+        Self::<()>::TSVariant(());
+        //~^ ERROR type arguments are not allowed on self type [E0109]
+        //~| ERROR mismatched types [E0308]
+        Self::<()>::TSVariant::<()>(());
+        //~^ ERROR type arguments are not allowed on self type [E0109]
+        //~| ERROR type arguments are not allowed on this type [E0109]
+    }
+
+    fn s_variant() {
+        Self::SVariant { v: () };
+        //~^ ERROR mismatched types [E0308]
+        Self::SVariant::<()> { v: () };
+        //~^ ERROR type arguments are not allowed on this type [E0109]
+        //~| ERROR mismatched types [E0308]
+        Self::<()>::SVariant { v: () };
+        //~^ ERROR type arguments are not allowed on self type [E0109]
+        //~| ERROR mismatched types [E0308]
+        Self::<()>::SVariant::<()> { v: () };
+        //~^ ERROR type arguments are not allowed on self type [E0109]
+        //~| ERROR type arguments are not allowed on this type [E0109]
+        //~| ERROR mismatched types [E0308]
+    }
+
+    fn u_variant() {
+        Self::UVariant::<()>;
+        //~^ ERROR type arguments are not allowed on this type [E0109]
+        Self::<()>::UVariant;
+        //~^ ERROR type arguments are not allowed on self type [E0109]
+        Self::<()>::UVariant::<()>;
+        //~^ ERROR type arguments are not allowed on self type [E0109]
+        //~| ERROR type arguments are not allowed on this type [E0109]
+    }
+}
+
+fn main() {
+    // Tuple struct variant
+
+    Enum::<()>::TSVariant::<()>(());
+    //~^ ERROR type arguments are not allowed on tuple variant `TSVariant` [E0109]
+
+    Alias::TSVariant::<()>(());
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+    Alias::<()>::TSVariant::<()>(());
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+
+    AliasFixed::TSVariant::<()>(());
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+    AliasFixed::<()>::TSVariant(());
+    //~^ ERROR this type alias takes 0 generic arguments but 1 generic argument was supplied [E0107]
+    AliasFixed::<()>::TSVariant::<()>(());
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+    //~| ERROR this type alias takes 0 generic arguments but 1 generic argument was supplied [E0107]
+
+    // Struct variant
+
+    Enum::<()>::SVariant::<()> { v: () };
+    //~^ ERROR type arguments are not allowed on variant `SVariant` [E0109]
+
+    Alias::SVariant::<()> { v: () };
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+    Alias::<()>::SVariant::<()> { v: () };
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+
+    AliasFixed::SVariant::<()> { v: () };
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+    AliasFixed::<()>::SVariant { v: () };
+    //~^ ERROR this type alias takes 0 generic arguments but 1 generic argument was supplied [E0107]
+    AliasFixed::<()>::SVariant::<()> { v: () };
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+    //~| ERROR this type alias takes 0 generic arguments but 1 generic argument was supplied [E0107]
+
+    // Unit variant
+
+    Enum::<()>::UVariant::<()>;
+    //~^ ERROR type arguments are not allowed on unit variant `UVariant` [E0109]
+
+    Alias::UVariant::<()>;
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+    Alias::<()>::UVariant::<()>;
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+
+    AliasFixed::UVariant::<()>;
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+    AliasFixed::<()>::UVariant;
+    //~^ ERROR this type alias takes 0 generic arguments but 1 generic argument was supplied [E0107]
+    AliasFixed::<()>::UVariant::<()>;
+    //~^ ERROR type arguments are not allowed on this type [E0109]
+    //~| ERROR this type alias takes 0 generic arguments but 1 generic argument was supplied [E0107]
+}
diff --git a/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.stderr b/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.stderr
new file mode 100644
index 000000000..a922d7a5e
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.stderr
@@ -0,0 +1,512 @@
+error[E0308]: mismatched types
+  --> $DIR/enum-variant-generic-args.rs:13:25
+   |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+LL |     fn ts_variant() {
+LL |         Self::TSVariant(());
+   |         --------------- ^^ expected type parameter `T`, found `()`
+   |         |
+   |         arguments to this enum variant are incorrect
+   |
+   = note: expected type parameter `T`
+                   found unit type `()`
+note: tuple variant defined here
+  --> $DIR/enum-variant-generic-args.rs:7:16
+   |
+LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
+   |                ^^^^^^^^^
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:15:27
+   |
+LL |         Self::TSVariant::<()>(());
+   |               ---------   ^^ type argument not allowed
+   |               |
+   |               not allowed on this type
+
+error[E0109]: type arguments are not allowed on self type
+  --> $DIR/enum-variant-generic-args.rs:17:16
+   |
+LL |         Self::<()>::TSVariant(());
+   |         ----   ^^ type argument not allowed
+   |         |
+   |         not allowed on self type
+   |
+note: `Self` is of type `Enum<T>`
+  --> $DIR/enum-variant-generic-args.rs:7:6
+   |
+LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
+   |      ^^^^ `Self` corresponds to this type
+...
+LL | impl<T> Enum<T> {
+   | --------------- `Self` is on type `Enum` in this `impl`
+help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
+   |
+LL |         Enum::<()>::TSVariant(());
+   |         ~~~~
+
+error[E0308]: mismatched types
+  --> $DIR/enum-variant-generic-args.rs:17:31
+   |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+...
+LL |         Self::<()>::TSVariant(());
+   |         --------------------- ^^ expected type parameter `T`, found `()`
+   |         |
+   |         arguments to this enum variant are incorrect
+   |
+   = note: expected type parameter `T`
+                   found unit type `()`
+note: tuple variant defined here
+  --> $DIR/enum-variant-generic-args.rs:7:16
+   |
+LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
+   |                ^^^^^^^^^
+
+error[E0109]: type arguments are not allowed on self type
+  --> $DIR/enum-variant-generic-args.rs:20:16
+   |
+LL |         Self::<()>::TSVariant::<()>(());
+   |         ----   ^^ type argument not allowed
+   |         |
+   |         not allowed on self type
+   |
+note: `Self` is of type `Enum<T>`
+  --> $DIR/enum-variant-generic-args.rs:7:6
+   |
+LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
+   |      ^^^^ `Self` corresponds to this type
+...
+LL | impl<T> Enum<T> {
+   | --------------- `Self` is on type `Enum` in this `impl`
+help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
+   |
+LL |         Enum::<()>::TSVariant::<()>(());
+   |         ~~~~
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:20:33
+   |
+LL |         Self::<()>::TSVariant::<()>(());
+   |                     ---------   ^^ type argument not allowed
+   |                     |
+   |                     not allowed on this type
+
+error[E0308]: mismatched types
+  --> $DIR/enum-variant-generic-args.rs:26:29
+   |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+...
+LL |         Self::SVariant { v: () };
+   |                             ^^ expected type parameter `T`, found `()`
+   |
+   = note: expected type parameter `T`
+                   found unit type `()`
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:28:26
+   |
+LL |         Self::SVariant::<()> { v: () };
+   |               --------   ^^ type argument not allowed
+   |               |
+   |               not allowed on this type
+   |
+   = note: enum variants can't have type parameters
+help: you might have meant to specity type parameters on enum `Enum`
+   |
+LL -         Self::SVariant::<()> { v: () };
+LL +         Enum::<()>::SVariant { v: () };
+   |
+
+error[E0308]: mismatched types
+  --> $DIR/enum-variant-generic-args.rs:28:35
+   |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+...
+LL |         Self::SVariant::<()> { v: () };
+   |                                   ^^ expected type parameter `T`, found `()`
+   |
+   = note: expected type parameter `T`
+                   found unit type `()`
+
+error[E0109]: type arguments are not allowed on self type
+  --> $DIR/enum-variant-generic-args.rs:31:16
+   |
+LL |         Self::<()>::SVariant { v: () };
+   |         ----   ^^ type argument not allowed
+   |         |
+   |         not allowed on self type
+   |
+note: `Self` is of type `Enum<T>`
+  --> $DIR/enum-variant-generic-args.rs:7:6
+   |
+LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
+   |      ^^^^ `Self` corresponds to this type
+...
+LL | impl<T> Enum<T> {
+   | --------------- `Self` is on type `Enum` in this `impl`
+help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
+   |
+LL |         Enum::<()>::SVariant { v: () };
+   |         ~~~~
+
+error[E0308]: mismatched types
+  --> $DIR/enum-variant-generic-args.rs:31:35
+   |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+...
+LL |         Self::<()>::SVariant { v: () };
+   |                                   ^^ expected type parameter `T`, found `()`
+   |
+   = note: expected type parameter `T`
+                   found unit type `()`
+
+error[E0109]: type arguments are not allowed on self type
+  --> $DIR/enum-variant-generic-args.rs:34:16
+   |
+LL |         Self::<()>::SVariant::<()> { v: () };
+   |         ----   ^^ type argument not allowed
+   |         |
+   |         not allowed on self type
+   |
+note: `Self` is of type `Enum<T>`
+  --> $DIR/enum-variant-generic-args.rs:7:6
+   |
+LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
+   |      ^^^^ `Self` corresponds to this type
+...
+LL | impl<T> Enum<T> {
+   | --------------- `Self` is on type `Enum` in this `impl`
+help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
+   |
+LL |         Enum::<()>::SVariant::<()> { v: () };
+   |         ~~~~
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:34:32
+   |
+LL |         Self::<()>::SVariant::<()> { v: () };
+   |                     --------   ^^ type argument not allowed
+   |                     |
+   |                     not allowed on this type
+   |
+   = note: enum variants can't have type parameters
+help: you might have meant to specity type parameters on enum `Enum`
+   |
+LL -         Self::<()>::SVariant::<()> { v: () };
+LL +         Enum::<()>::SVariant { v: () };
+   |
+
+error[E0308]: mismatched types
+  --> $DIR/enum-variant-generic-args.rs:34:41
+   |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+...
+LL |         Self::<()>::SVariant::<()> { v: () };
+   |                                         ^^ expected type parameter `T`, found `()`
+   |
+   = note: expected type parameter `T`
+                   found unit type `()`
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:41:26
+   |
+LL |         Self::UVariant::<()>;
+   |               --------   ^^ type argument not allowed
+   |               |
+   |               not allowed on this type
+
+error[E0109]: type arguments are not allowed on self type
+  --> $DIR/enum-variant-generic-args.rs:43:16
+   |
+LL |         Self::<()>::UVariant;
+   |         ----   ^^ type argument not allowed
+   |         |
+   |         not allowed on self type
+   |
+note: `Self` is of type `Enum<T>`
+  --> $DIR/enum-variant-generic-args.rs:7:6
+   |
+LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
+   |      ^^^^ `Self` corresponds to this type
+...
+LL | impl<T> Enum<T> {
+   | --------------- `Self` is on type `Enum` in this `impl`
+help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
+   |
+LL |         Enum::<()>::UVariant;
+   |         ~~~~
+
+error[E0109]: type arguments are not allowed on self type
+  --> $DIR/enum-variant-generic-args.rs:45:16
+   |
+LL |         Self::<()>::UVariant::<()>;
+   |         ----   ^^ type argument not allowed
+   |         |
+   |         not allowed on self type
+   |
+note: `Self` is of type `Enum<T>`
+  --> $DIR/enum-variant-generic-args.rs:7:6
+   |
+LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
+   |      ^^^^ `Self` corresponds to this type
+...
+LL | impl<T> Enum<T> {
+   | --------------- `Self` is on type `Enum` in this `impl`
+help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
+   |
+LL |         Enum::<()>::UVariant::<()>;
+   |         ~~~~
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:45:32
+   |
+LL |         Self::<()>::UVariant::<()>;
+   |                     --------   ^^ type argument not allowed
+   |                     |
+   |                     not allowed on this type
+
+error[E0109]: type arguments are not allowed on tuple variant `TSVariant`
+  --> $DIR/enum-variant-generic-args.rs:54:29
+   |
+LL |     Enum::<()>::TSVariant::<()>(());
+   |                 ---------   ^^ type argument not allowed
+   |                 |
+   |                 not allowed on tuple variant `TSVariant`
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:57:24
+   |
+LL |     Alias::TSVariant::<()>(());
+   |            ---------   ^^ type argument not allowed
+   |            |
+   |            not allowed on this type
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:59:30
+   |
+LL |     Alias::<()>::TSVariant::<()>(());
+   |                  ---------   ^^ type argument not allowed
+   |                  |
+   |                  not allowed on this type
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:62:29
+   |
+LL |     AliasFixed::TSVariant::<()>(());
+   |                 ---------   ^^ type argument not allowed
+   |                 |
+   |                 not allowed on this type
+
+error[E0107]: this type alias takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/enum-variant-generic-args.rs:64:5
+   |
+LL |     AliasFixed::<()>::TSVariant(());
+   |     ^^^^^^^^^^------ help: remove these generics
+   |     |
+   |     expected 0 generic arguments
+   |
+note: type alias defined here, with 0 generic parameters
+  --> $DIR/enum-variant-generic-args.rs:9:6
+   |
+LL | type AliasFixed = Enum<()>;
+   |      ^^^^^^^^^^
+
+error[E0107]: this type alias takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/enum-variant-generic-args.rs:66:5
+   |
+LL |     AliasFixed::<()>::TSVariant::<()>(());
+   |     ^^^^^^^^^^------ help: remove these generics
+   |     |
+   |     expected 0 generic arguments
+   |
+note: type alias defined here, with 0 generic parameters
+  --> $DIR/enum-variant-generic-args.rs:9:6
+   |
+LL | type AliasFixed = Enum<()>;
+   |      ^^^^^^^^^^
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:66:35
+   |
+LL |     AliasFixed::<()>::TSVariant::<()>(());
+   |                       ---------   ^^ type argument not allowed
+   |                       |
+   |                       not allowed on this type
+
+error[E0109]: type arguments are not allowed on variant `SVariant`
+  --> $DIR/enum-variant-generic-args.rs:72:28
+   |
+LL |     Enum::<()>::SVariant::<()> { v: () };
+   |                 --------   ^^ type argument not allowed
+   |                 |
+   |                 not allowed on variant `SVariant`
+   |
+   = note: enum variants can't have type parameters
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:75:23
+   |
+LL |     Alias::SVariant::<()> { v: () };
+   |            --------   ^^ type argument not allowed
+   |            |
+   |            not allowed on this type
+   |
+   = note: enum variants can't have type parameters
+help: you might have meant to specity type parameters on enum `Enum`
+   |
+LL -     Alias::SVariant::<()> { v: () };
+LL +     Alias::<()>::SVariant { v: () };
+   |
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:77:29
+   |
+LL |     Alias::<()>::SVariant::<()> { v: () };
+   |                  --------   ^^ type argument not allowed
+   |                  |
+   |                  not allowed on this type
+   |
+   = note: enum variants can't have type parameters
+help: you might have meant to specity type parameters on enum `Enum`
+   |
+LL -     Alias::<()>::SVariant::<()> { v: () };
+LL +     Alias::<()>::SVariant { v: () };
+   |
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:80:28
+   |
+LL |     AliasFixed::SVariant::<()> { v: () };
+   |                 --------   ^^ type argument not allowed
+   |                 |
+   |                 not allowed on this type
+   |
+   = note: enum variants can't have type parameters
+help: you might have meant to specity type parameters on enum `Enum`
+   |
+LL -     AliasFixed::SVariant::<()> { v: () };
+LL +     AliasFixed::<()>::SVariant { v: () };
+   |
+
+error[E0107]: this type alias takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/enum-variant-generic-args.rs:82:5
+   |
+LL |     AliasFixed::<()>::SVariant { v: () };
+   |     ^^^^^^^^^^------ help: remove these generics
+   |     |
+   |     expected 0 generic arguments
+   |
+note: type alias defined here, with 0 generic parameters
+  --> $DIR/enum-variant-generic-args.rs:9:6
+   |
+LL | type AliasFixed = Enum<()>;
+   |      ^^^^^^^^^^
+
+error[E0107]: this type alias takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/enum-variant-generic-args.rs:84:5
+   |
+LL |     AliasFixed::<()>::SVariant::<()> { v: () };
+   |     ^^^^^^^^^^------ help: remove these generics
+   |     |
+   |     expected 0 generic arguments
+   |
+note: type alias defined here, with 0 generic parameters
+  --> $DIR/enum-variant-generic-args.rs:9:6
+   |
+LL | type AliasFixed = Enum<()>;
+   |      ^^^^^^^^^^
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:84:34
+   |
+LL |     AliasFixed::<()>::SVariant::<()> { v: () };
+   |                       --------   ^^ type argument not allowed
+   |                       |
+   |                       not allowed on this type
+   |
+   = note: enum variants can't have type parameters
+help: you might have meant to specity type parameters on enum `Enum`
+   |
+LL -     AliasFixed::<()>::SVariant::<()> { v: () };
+LL +     AliasFixed::<()>::SVariant { v: () };
+   |
+
+error[E0109]: type arguments are not allowed on unit variant `UVariant`
+  --> $DIR/enum-variant-generic-args.rs:90:28
+   |
+LL |     Enum::<()>::UVariant::<()>;
+   |                 --------   ^^ type argument not allowed
+   |                 |
+   |                 not allowed on unit variant `UVariant`
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:93:23
+   |
+LL |     Alias::UVariant::<()>;
+   |            --------   ^^ type argument not allowed
+   |            |
+   |            not allowed on this type
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:95:29
+   |
+LL |     Alias::<()>::UVariant::<()>;
+   |                  --------   ^^ type argument not allowed
+   |                  |
+   |                  not allowed on this type
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:98:28
+   |
+LL |     AliasFixed::UVariant::<()>;
+   |                 --------   ^^ type argument not allowed
+   |                 |
+   |                 not allowed on this type
+
+error[E0107]: this type alias takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/enum-variant-generic-args.rs:100:5
+   |
+LL |     AliasFixed::<()>::UVariant;
+   |     ^^^^^^^^^^------ help: remove these generics
+   |     |
+   |     expected 0 generic arguments
+   |
+note: type alias defined here, with 0 generic parameters
+  --> $DIR/enum-variant-generic-args.rs:9:6
+   |
+LL | type AliasFixed = Enum<()>;
+   |      ^^^^^^^^^^
+
+error[E0107]: this type alias takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/enum-variant-generic-args.rs:102:5
+   |
+LL |     AliasFixed::<()>::UVariant::<()>;
+   |     ^^^^^^^^^^------ help: remove these generics
+   |     |
+   |     expected 0 generic arguments
+   |
+note: type alias defined here, with 0 generic parameters
+  --> $DIR/enum-variant-generic-args.rs:9:6
+   |
+LL | type AliasFixed = Enum<()>;
+   |      ^^^^^^^^^^
+
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/enum-variant-generic-args.rs:102:34
+   |
+LL |     AliasFixed::<()>::UVariant::<()>;
+   |                       --------   ^^ type argument not allowed
+   |                       |
+   |                       not allowed on this type
+
+error: aborting due to 39 previous errors
+
+Some errors have detailed explanations: E0107, E0109, E0308.
+For more information about an error, try `rustc --explain E0107`.
diff --git a/src/test/ui/type-alias-enum-variants/enum-variant-priority-higher-than-other-inherent.rs b/src/test/ui/type-alias-enum-variants/enum-variant-priority-higher-than-other-inherent.rs
new file mode 100644
index 000000000..3a8712f2a
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/enum-variant-priority-higher-than-other-inherent.rs
@@ -0,0 +1,23 @@
+// Check that an `enum` variant is resolved, in the value namespace,
+// with higher priority than other inherent items when there is a conflict.
+
+enum E {
+    V(u8)
+}
+
+impl E {
+    fn V() {}
+}
+
+enum E2 {
+    V,
+}
+
+impl E2 {
+    const V: u8 = 0;
+}
+
+fn main() {
+    <E>::V(); //~ ERROR this enum variant takes 1 argument but 0 arguments were supplied
+    let _: u8 = <E2>::V; //~ ERROR mismatched types
+}
diff --git a/src/test/ui/type-alias-enum-variants/enum-variant-priority-higher-than-other-inherent.stderr b/src/test/ui/type-alias-enum-variants/enum-variant-priority-higher-than-other-inherent.stderr
new file mode 100644
index 000000000..006253f84
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/enum-variant-priority-higher-than-other-inherent.stderr
@@ -0,0 +1,28 @@
+error[E0061]: this enum variant takes 1 argument but 0 arguments were supplied
+  --> $DIR/enum-variant-priority-higher-than-other-inherent.rs:21:5
+   |
+LL |     <E>::V();
+   |     ^^^^^^-- an argument of type `u8` is missing
+   |
+note: tuple variant defined here
+  --> $DIR/enum-variant-priority-higher-than-other-inherent.rs:5:5
+   |
+LL |     V(u8)
+   |     ^
+help: provide the argument
+   |
+LL |     <E>::V(/* u8 */);
+   |     ~~~~~~~~~~~~~~~~
+
+error[E0308]: mismatched types
+  --> $DIR/enum-variant-priority-higher-than-other-inherent.rs:22:17
+   |
+LL |     let _: u8 = <E2>::V;
+   |            --   ^^^^^^^ expected `u8`, found enum `E2`
+   |            |
+   |            expected due to this
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0061, E0308.
+For more information about an error, try `rustc --explain E0061`.
diff --git a/src/test/ui/type-alias-enum-variants/enum-variant-priority-lint-ambiguous_associated_items.rs b/src/test/ui/type-alias-enum-variants/enum-variant-priority-lint-ambiguous_associated_items.rs
new file mode 100644
index 000000000..acbf15dcb
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/enum-variant-priority-lint-ambiguous_associated_items.rs
@@ -0,0 +1,41 @@
+// Check that a projection `Self::V` in a trait implementation,
+// with an associated type named `V`, for an `enum` with a variant named `V`,
+// results in triggering the deny-by-default lint `ambiguous_associated_items`.
+// The lint suggests that qualified syntax should be used instead.
+// That is, the user would write `<Self as Tr>::V`.
+//
+// The rationale for this is that while `enum` variants do currently
+// not exist in the type namespace but solely in the value namespace,
+// RFC #2593 "Enum variant types", would add enum variants to the type namespace.
+// However, currently `enum` variants are resolved with high priority as
+// they are resolved as inherent associated items.
+// Should #2953 therefore be implemented, `Self::V` would suddenly switch
+// from referring to the associated type `V` instead of the variant `V`.
+// The lint exists to keep us forward compatible with #2593.
+//
+// As a closing note, provided that #2933 was implemented and
+// if `enum` variants were given lower priority than associated types,
+// it would be impossible to refer to the `enum` variant `V` whereas
+// the associated type could be referred to with qualified syntax as seen above.
+
+enum E {
+    V
+}
+
+trait Tr {
+    type V;
+    fn f() -> Self::V;
+}
+
+impl Tr for E {
+    type V = u8;
+    fn f() -> Self::V { 0 }
+    //~^ ERROR ambiguous associated item
+    //~| ERROR ambiguous associated item
+    //~| WARN this was previously accepted
+    //~| WARN this was previously accepted
+    //~| HELP use fully-qualified syntax
+    //~| HELP use fully-qualified syntax
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-enum-variants/enum-variant-priority-lint-ambiguous_associated_items.stderr b/src/test/ui/type-alias-enum-variants/enum-variant-priority-lint-ambiguous_associated_items.stderr
new file mode 100644
index 000000000..aaa3159e0
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/enum-variant-priority-lint-ambiguous_associated_items.stderr
@@ -0,0 +1,41 @@
+error: ambiguous associated item
+  --> $DIR/enum-variant-priority-lint-ambiguous_associated_items.rs:32:15
+   |
+LL |     fn f() -> Self::V { 0 }
+   |               ^^^^^^^ help: use fully-qualified syntax: `<E as Tr>::V`
+   |
+   = note: `#[deny(ambiguous_associated_items)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #57644 <https://github.com/rust-lang/rust/issues/57644>
+note: `V` could refer to the variant defined here
+  --> $DIR/enum-variant-priority-lint-ambiguous_associated_items.rs:22:5
+   |
+LL |     V
+   |     ^
+note: `V` could also refer to the associated type defined here
+  --> $DIR/enum-variant-priority-lint-ambiguous_associated_items.rs:26:5
+   |
+LL |     type V;
+   |     ^^^^^^
+
+error: ambiguous associated item
+  --> $DIR/enum-variant-priority-lint-ambiguous_associated_items.rs:32:15
+   |
+LL |     fn f() -> Self::V { 0 }
+   |               ^^^^^^^ help: use fully-qualified syntax: `<E as Tr>::V`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #57644 <https://github.com/rust-lang/rust/issues/57644>
+note: `V` could refer to the variant defined here
+  --> $DIR/enum-variant-priority-lint-ambiguous_associated_items.rs:22:5
+   |
+LL |     V
+   |     ^
+note: `V` could also refer to the associated type defined here
+  --> $DIR/enum-variant-priority-lint-ambiguous_associated_items.rs:26:5
+   |
+LL |     type V;
+   |     ^^^^^^
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-Self-issue-58006.rs b/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-Self-issue-58006.rs
new file mode 100644
index 000000000..ab40bf580
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-Self-issue-58006.rs
@@ -0,0 +1,14 @@
+pub enum Enum {
+    A(usize),
+}
+
+impl Enum {
+    fn foo(&self) -> () {
+        match self {
+            Self::A => (),
+            //~^ ERROR expected unit struct, unit variant or constant, found tuple variant
+        }
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-Self-issue-58006.stderr b/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-Self-issue-58006.stderr
new file mode 100644
index 000000000..15d15f2f4
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-Self-issue-58006.stderr
@@ -0,0 +1,9 @@
+error[E0533]: expected unit struct, unit variant or constant, found tuple variant `Self::A`
+  --> $DIR/incorrect-variant-form-through-Self-issue-58006.rs:8:13
+   |
+LL |             Self::A => (),
+   |             ^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0533`.
diff --git a/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-alias-caught.rs b/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-alias-caught.rs
new file mode 100644
index 000000000..e4abb96b4
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-alias-caught.rs
@@ -0,0 +1,19 @@
+// Check that creating/matching on an enum variant through an alias with
+// the wrong braced/unit form is caught as an error.
+
+enum Enum { Braced {}, Unit, Tuple() }
+type Alias = Enum;
+
+fn main() {
+    Alias::Braced;
+    //~^ ERROR expected unit struct, unit variant or constant, found struct variant `Alias::Braced` [E0533]
+    let Alias::Braced = panic!();
+    //~^ ERROR expected unit struct, unit variant or constant, found struct variant `Alias::Braced` [E0533]
+    let Alias::Braced(..) = panic!();
+    //~^ ERROR expected tuple struct or tuple variant, found struct variant `Alias::Braced` [E0164]
+
+    Alias::Unit();
+    //~^ ERROR expected function, found enum variant `Alias::Unit`
+    let Alias::Unit() = panic!();
+    //~^ ERROR expected tuple struct or tuple variant, found unit variant `Alias::Unit` [E0164]
+}
diff --git a/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-alias-caught.stderr b/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-alias-caught.stderr
new file mode 100644
index 000000000..8f3180a86
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/incorrect-variant-form-through-alias-caught.stderr
@@ -0,0 +1,45 @@
+error[E0533]: expected unit struct, unit variant or constant, found struct variant `Alias::Braced`
+  --> $DIR/incorrect-variant-form-through-alias-caught.rs:8:5
+   |
+LL |     Alias::Braced;
+   |     ^^^^^^^^^^^^^
+
+error[E0533]: expected unit struct, unit variant or constant, found struct variant `Alias::Braced`
+  --> $DIR/incorrect-variant-form-through-alias-caught.rs:10:9
+   |
+LL |     let Alias::Braced = panic!();
+   |         ^^^^^^^^^^^^^
+
+error[E0164]: expected tuple struct or tuple variant, found struct variant `Alias::Braced`
+  --> $DIR/incorrect-variant-form-through-alias-caught.rs:12:9
+   |
+LL |     let Alias::Braced(..) = panic!();
+   |         ^^^^^^^^^^^^^^^^^ not a tuple variant or struct
+
+error[E0618]: expected function, found enum variant `Alias::Unit`
+  --> $DIR/incorrect-variant-form-through-alias-caught.rs:15:5
+   |
+LL | enum Enum { Braced {}, Unit, Tuple() }
+   |                        ---- enum variant `Alias::Unit` defined here
+...
+LL |     Alias::Unit();
+   |     ^^^^^^^^^^^--
+   |     |
+   |     call expression requires function
+   |
+help: `Alias::Unit` is a unit enum variant, and does not take parentheses to be constructed
+   |
+LL -     Alias::Unit();
+LL +     Alias::Unit;
+   |
+
+error[E0164]: expected tuple struct or tuple variant, found unit variant `Alias::Unit`
+  --> $DIR/incorrect-variant-form-through-alias-caught.rs:17:9
+   |
+LL |     let Alias::Unit() = panic!();
+   |         ^^^^^^^^^^^^^ not a tuple variant or struct
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0164, E0533, E0618.
+For more information about an error, try `rustc --explain E0164`.
diff --git a/src/test/ui/type-alias-enum-variants/issue-57866.rs b/src/test/ui/type-alias-enum-variants/issue-57866.rs
new file mode 100644
index 000000000..5e105b20a
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/issue-57866.rs
@@ -0,0 +1,24 @@
+// check-pass
+
+enum Outer<T> {
+    A(T)
+}
+
+enum Inner {
+    A(i32)
+}
+
+type OuterAlias = Outer<Inner>;
+
+fn ice(x: OuterAlias) {
+    // Fine
+    match x {
+        OuterAlias::A(Inner::A(_)) => (),
+    }
+    // Not fine
+    match x {
+        OuterAlias::A(Inner::A(y)) => (),
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-enum-variants/issue-61801-path-pattern-can-infer.rs b/src/test/ui/type-alias-enum-variants/issue-61801-path-pattern-can-infer.rs
new file mode 100644
index 000000000..9c9eaab8d
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/issue-61801-path-pattern-can-infer.rs
@@ -0,0 +1,28 @@
+// In this regression test we check that a path pattern referring to a unit variant
+// through a type alias is successful in inferring the generic argument.
+
+// check-pass
+
+enum Opt<T> {
+    N,
+    S(T),
+}
+
+type OptAlias<T> = Opt<T>;
+
+fn f1(x: OptAlias<u8>) {
+    match x {
+        OptAlias::N // We previously failed to infer `T` to `u8`.
+            => (),
+        _ => (),
+    }
+
+    match x {
+        <
+            OptAlias<_> // And we failed to infer this type also.
+        >::N => (),
+        _ => (),
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-enum-variants/issue-63151-dead-code-lint-fields-in-patterns.rs b/src/test/ui/type-alias-enum-variants/issue-63151-dead-code-lint-fields-in-patterns.rs
new file mode 100644
index 000000000..66fb8dd0d
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/issue-63151-dead-code-lint-fields-in-patterns.rs
@@ -0,0 +1,26 @@
+// check-pass
+
+// Regression test for the issue #63151:
+// Spurious unused field warning when matching variants under a `Self` scope
+//
+// This test checks that the `dead_code` lint properly inspects fields
+// in struct patterns that use a type relative path.
+
+#![deny(dead_code)]
+
+enum Enum {
+    Variant { field: usize }
+}
+
+impl Enum {
+    fn read_field(self) -> usize {
+        match self {
+            Self::Variant { field } => field
+        }
+    }
+}
+
+fn main() {
+    let e = Enum::Variant { field: 42 };
+    println!("{}", e.read_field());
+}
diff --git a/src/test/ui/type-alias-enum-variants/no-type-application-on-aliased-enum-variant.rs b/src/test/ui/type-alias-enum-variants/no-type-application-on-aliased-enum-variant.rs
new file mode 100644
index 000000000..872ece0c0
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/no-type-application-on-aliased-enum-variant.rs
@@ -0,0 +1,14 @@
+// Check that a generic type for an `enum` admits type application
+// on both the type constructor and the generic type's variant.
+//
+// Also check that a type alias to said generic type admits type application
+// on the type constructor but *NOT* the variant.
+
+type Alias<T> = Option<T>;
+
+fn main() {
+    let _ = Option::<u8>::None; // OK
+    let _ = Option::None::<u8>; // OK (Lint in future!)
+    let _ = Alias::<u8>::None; // OK
+    let _ = Alias::None::<u8>; //~ ERROR type arguments are not allowed on this type
+}
diff --git a/src/test/ui/type-alias-enum-variants/no-type-application-on-aliased-enum-variant.stderr b/src/test/ui/type-alias-enum-variants/no-type-application-on-aliased-enum-variant.stderr
new file mode 100644
index 000000000..51b1c8a10
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/no-type-application-on-aliased-enum-variant.stderr
@@ -0,0 +1,11 @@
+error[E0109]: type arguments are not allowed on this type
+  --> $DIR/no-type-application-on-aliased-enum-variant.rs:13:27
+   |
+LL |     let _ = Alias::None::<u8>;
+   |                    ----   ^^ type argument not allowed
+   |                    |
+   |                    not allowed on this type
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0109`.
diff --git a/src/test/ui/type-alias-enum-variants/resolve-to-enum-variant-in-type-namespace-and-error.rs b/src/test/ui/type-alias-enum-variants/resolve-to-enum-variant-in-type-namespace-and-error.rs
new file mode 100644
index 000000000..11f4b05d0
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/resolve-to-enum-variant-in-type-namespace-and-error.rs
@@ -0,0 +1,11 @@
+// Check that the compiler will resolve `<E>::V` to the variant `V` in the type namespace
+// but will reject this because `enum` variants do not exist in the type namespace.
+
+enum E {
+    V
+}
+
+fn check() -> <E>::V {}
+//~^ ERROR expected type, found variant `V`
+
+fn main() {}
diff --git a/src/test/ui/type-alias-enum-variants/resolve-to-enum-variant-in-type-namespace-and-error.stderr b/src/test/ui/type-alias-enum-variants/resolve-to-enum-variant-in-type-namespace-and-error.stderr
new file mode 100644
index 000000000..f190bfb69
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/resolve-to-enum-variant-in-type-namespace-and-error.stderr
@@ -0,0 +1,8 @@
+error: expected type, found variant `V`
+  --> $DIR/resolve-to-enum-variant-in-type-namespace-and-error.rs:8:15
+   |
+LL | fn check() -> <E>::V {}
+   |               ^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-enum-variants/self-in-enum-definition.rs b/src/test/ui/type-alias-enum-variants/self-in-enum-definition.rs
new file mode 100644
index 000000000..8dadd77fc
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/self-in-enum-definition.rs
@@ -0,0 +1,8 @@
+#[repr(u8)]
+enum Alpha {
+    V1 = 41,
+    V2 = Self::V1 as u8 + 1,    // OK; See #50072.
+    V3 = Self::V1 {} as u8 + 2, //~ ERROR cycle detected when simplifying constant
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-enum-variants/self-in-enum-definition.stderr b/src/test/ui/type-alias-enum-variants/self-in-enum-definition.stderr
new file mode 100644
index 000000000..4775e6882
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/self-in-enum-definition.stderr
@@ -0,0 +1,33 @@
+error[E0391]: cycle detected when simplifying constant for the type system `Alpha::V3::{constant#0}`
+  --> $DIR/self-in-enum-definition.rs:5:10
+   |
+LL |     V3 = Self::V1 {} as u8 + 2,
+   |          ^^^^^^^^^^^^^^^^^^^^^
+   |
+note: ...which requires simplifying constant for the type system `Alpha::V3::{constant#0}`...
+  --> $DIR/self-in-enum-definition.rs:5:10
+   |
+LL |     V3 = Self::V1 {} as u8 + 2,
+   |          ^^^^^^^^^^^^^^^^^^^^^
+note: ...which requires const-evaluating + checking `Alpha::V3::{constant#0}`...
+  --> $DIR/self-in-enum-definition.rs:5:10
+   |
+LL |     V3 = Self::V1 {} as u8 + 2,
+   |          ^^^^^^^^^^^^^^^^^^^^^
+   = note: ...which requires computing layout of `Alpha`...
+   = note: ...which again requires simplifying constant for the type system `Alpha::V3::{constant#0}`, completing the cycle
+note: cycle used when collecting item types in top-level module
+  --> $DIR/self-in-enum-definition.rs:1:1
+   |
+LL | / #[repr(u8)]
+LL | | enum Alpha {
+LL | |     V1 = 41,
+LL | |     V2 = Self::V1 as u8 + 1,    // OK; See #50072.
+...  |
+LL | |
+LL | | fn main() {}
+   | |____________^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0391`.
diff --git a/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-pass.rs b/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-pass.rs
new file mode 100644
index 000000000..39677733d
--- /dev/null
+++ b/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-pass.rs
@@ -0,0 +1,69 @@
+// run-pass
+
+// Check that it is possible to resolve, in the value namespace,
+// to an `enum` variant through a type alias. This includes `Self`.
+// Type qualified syntax `<Type>::Variant` also works when syntactically valid.
+
+#[derive(Debug, PartialEq, Eq)]
+enum Foo {
+    Bar(i32),
+    Baz { i: i32 },
+    Qux,
+}
+
+type FooAlias = Foo;
+type OptionAlias = Option<i32>;
+
+macro_rules! check_pat {
+    ($x:expr, $p:pat) => {
+        assert!(if let $p = $x { true } else { false });
+    };
+}
+
+impl Foo {
+    fn bar() -> Self {
+        let x = Self::Bar(3);
+        assert_eq!(x, <Self>::Bar(3));
+        check_pat!(x, Self::Bar(3));
+        x
+    }
+
+    fn baz() -> Self {
+        let x = Self::Baz { i: 42 };
+        check_pat!(x, Self::Baz { i: 42 });
+        x
+    }
+
+    fn qux() -> Self {
+        let x = Self::Qux;
+        assert_eq!(x, <Self>::Qux);
+        check_pat!(x, Self::Qux);
+        check_pat!(x, <Self>::Qux);
+        x
+    }
+}
+
+fn main() {
+    let bar = Foo::Bar(1);
+    assert_eq!(bar, FooAlias::Bar(1));
+    assert_eq!(bar, <FooAlias>::Bar(1));
+    check_pat!(bar, FooAlias::Bar(1));
+
+    let baz = FooAlias::Baz { i: 2 };
+    assert_eq!(baz, Foo::Baz { i: 2 });
+    check_pat!(baz, FooAlias::Baz { i: 2 });
+
+    let qux = Foo::Qux;
+    assert_eq!(qux, FooAlias::Qux);
+    assert_eq!(qux, <FooAlias>::Qux);
+    check_pat!(qux, FooAlias::Qux);
+    check_pat!(qux, <FooAlias>::Qux);
+
+    assert_eq!(Foo::bar(), Foo::Bar(3));
+    assert_eq!(Foo::baz(), Foo::Baz { i: 42 });
+    assert_eq!(Foo::qux(), Foo::Qux);
+
+    let some = Option::Some(4);
+    assert_eq!(some, OptionAlias::Some(4));
+    check_pat!(some, OptionAlias::Some(4));
+}
diff --git a/src/test/ui/type-alias-impl-trait/argument-types.rs b/src/test/ui/type-alias-impl-trait/argument-types.rs
new file mode 100644
index 000000000..185207b98
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/argument-types.rs
@@ -0,0 +1,26 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+// check-pass
+use std::fmt::Debug;
+
+type Foo = impl Debug;
+
+fn foo1(mut x: Foo) {
+    x = 22_u32;
+}
+
+fn foo2(mut x: Foo) {
+    // no constraint on x
+}
+
+fn foo3(x: Foo) {
+    println!("{:?}", x);
+}
+
+fn foo_value() -> Foo {
+    11_u32
+}
+
+fn main() {
+    foo3(foo_value());
+}
diff --git a/src/test/ui/type-alias-impl-trait/assoc-projection-ice.rs b/src/test/ui/type-alias-impl-trait/assoc-projection-ice.rs
new file mode 100644
index 000000000..703e3e869
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/assoc-projection-ice.rs
@@ -0,0 +1,24 @@
+#![feature(type_alias_impl_trait)]
+
+// build-pass
+
+trait T { type Item; }
+
+type Alias<'a> = impl T<Item = &'a ()>;
+
+struct S;
+impl<'a> T for &'a S {
+    type Item = &'a ();
+}
+
+fn filter_positive<'a>() -> Alias<'a> {
+    &S
+}
+
+fn with_positive(fun: impl Fn(Alias<'_>)) {
+    fun(filter_positive());
+}
+
+fn main() {
+    with_positive(|_| ());
+}
diff --git a/src/test/ui/type-alias-impl-trait/assoc-type-const.rs b/src/test/ui/type-alias-impl-trait/assoc-type-const.rs
new file mode 100644
index 000000000..0ade36daf
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/assoc-type-const.rs
@@ -0,0 +1,32 @@
+// Tests that we properly detect defining usages when using
+// const generics in an associated opaque type
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+trait UnwrapItemsExt<'a, const C: usize> {
+    type Iter;
+    fn unwrap_items(self) -> Self::Iter;
+}
+
+struct MyStruct<const C: usize> {}
+
+trait MyTrait<'a, const C: usize> {
+    type MyItem;
+    const MY_CONST: usize;
+}
+
+impl<'a, const C: usize> MyTrait<'a, C> for MyStruct<C> {
+    type MyItem = u8;
+    const MY_CONST: usize = C;
+}
+
+impl<'a, I, const C: usize> UnwrapItemsExt<'a, C> for I {
+    type Iter = impl MyTrait<'a, C>;
+
+    fn unwrap_items(self) -> Self::Iter {
+        MyStruct::<C> {}
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/assoc-type-lifetime-unconstrained.rs b/src/test/ui/type-alias-impl-trait/assoc-type-lifetime-unconstrained.rs
new file mode 100644
index 000000000..3f34b00ec
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/assoc-type-lifetime-unconstrained.rs
@@ -0,0 +1,26 @@
+// Tests that we don't allow unconstrained lifetime parameters in impls when
+// the lifetime is used in an associated opaque type.
+
+#![feature(type_alias_impl_trait)]
+
+trait UnwrapItemsExt {
+    type Iter;
+    fn unwrap_items(self) -> Self::Iter;
+}
+
+struct MyStruct {}
+
+trait MyTrait<'a> {}
+
+impl<'a> MyTrait<'a> for MyStruct {}
+
+impl<'a, I> UnwrapItemsExt for I {
+    //~^ ERROR the lifetime parameter `'a` is not constrained
+    type Iter = impl MyTrait<'a>;
+
+    fn unwrap_items(self) -> Self::Iter {
+        MyStruct {}
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/assoc-type-lifetime-unconstrained.stderr b/src/test/ui/type-alias-impl-trait/assoc-type-lifetime-unconstrained.stderr
new file mode 100644
index 000000000..e594dc577
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/assoc-type-lifetime-unconstrained.stderr
@@ -0,0 +1,9 @@
+error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/assoc-type-lifetime-unconstrained.rs:17:6
+   |
+LL | impl<'a, I> UnwrapItemsExt for I {
+   |      ^^ unconstrained lifetime parameter
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0207`.
diff --git a/src/test/ui/type-alias-impl-trait/assoc-type-lifetime.rs b/src/test/ui/type-alias-impl-trait/assoc-type-lifetime.rs
new file mode 100644
index 000000000..39f785d8c
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/assoc-type-lifetime.rs
@@ -0,0 +1,26 @@
+// Tests that we still detect defining usages when
+// lifetimes are used in an associated opaque type
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+trait UnwrapItemsExt<'a> {
+    type Iter;
+    fn unwrap_items(self) -> Self::Iter;
+}
+
+struct MyStruct {}
+
+trait MyTrait<'a> {}
+
+impl<'a> MyTrait<'a> for MyStruct {}
+
+impl<'a, I> UnwrapItemsExt<'a> for I {
+    type Iter = impl MyTrait<'a>;
+
+    fn unwrap_items(self) -> Self::Iter {
+        MyStruct {}
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/associated-type-alias-impl-trait.rs b/src/test/ui/type-alias-impl-trait/associated-type-alias-impl-trait.rs
new file mode 100644
index 000000000..42f07d49f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/associated-type-alias-impl-trait.rs
@@ -0,0 +1,26 @@
+#![feature(type_alias_impl_trait)]
+// build-pass (FIXME(62277): could be check-pass?)
+
+trait Bar {}
+struct Dummy;
+impl Bar for Dummy {}
+
+trait Foo {
+    type Assoc: Bar;
+    fn foo() -> Self::Assoc;
+    fn bar() -> Self::Assoc;
+}
+
+type Helper = impl Bar;
+
+impl Foo for i32 {
+    type Assoc = Helper;
+    fn foo() -> Helper {
+        Dummy
+    }
+    fn bar() -> Helper {
+        Dummy
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/auto-trait-leakage.rs b/src/test/ui/type-alias-impl-trait/auto-trait-leakage.rs
new file mode 100644
index 000000000..a1584581e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/auto-trait-leakage.rs
@@ -0,0 +1,18 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+mod m {
+    type Foo = impl std::fmt::Debug;
+
+    pub fn foo() -> Foo {
+        22_u32
+    }
+}
+
+fn is_send<T: Send>(_: T) {}
+
+fn main() {
+    is_send(m::foo());
+}
diff --git a/src/test/ui/type-alias-impl-trait/auto-trait-leakage2.rs b/src/test/ui/type-alias-impl-trait/auto-trait-leakage2.rs
new file mode 100644
index 000000000..fc89b0e87
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/auto-trait-leakage2.rs
@@ -0,0 +1,25 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+mod m {
+    use std::rc::Rc;
+
+    type Foo = impl std::fmt::Debug; //~ NOTE appears within the type
+    //~^ within this `Foo`
+    //~| expansion of desugaring
+
+    pub fn foo() -> Foo {
+        Rc::new(22_u32)
+    }
+}
+
+fn is_send<T: Send>(_: T) {}
+//~^ required by this bound
+//~| required by a bound
+
+fn main() {
+    is_send(m::foo());
+    //~^ ERROR: `Rc<u32>` cannot be sent between threads safely [E0277]
+    //~| NOTE cannot be sent
+    //~| NOTE required by a bound
+}
diff --git a/src/test/ui/type-alias-impl-trait/auto-trait-leakage2.stderr b/src/test/ui/type-alias-impl-trait/auto-trait-leakage2.stderr
new file mode 100644
index 000000000..d7247302d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/auto-trait-leakage2.stderr
@@ -0,0 +1,26 @@
+error[E0277]: `Rc<u32>` cannot be sent between threads safely
+  --> $DIR/auto-trait-leakage2.rs:21:13
+   |
+LL |     type Foo = impl std::fmt::Debug;
+   |                -------------------- within this `Foo`
+...
+LL |     is_send(m::foo());
+   |     ------- ^^^^^^^^ `Rc<u32>` cannot be sent between threads safely
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: within `Foo`, the trait `Send` is not implemented for `Rc<u32>`
+note: required because it appears within the type `Foo`
+  --> $DIR/auto-trait-leakage2.rs:7:16
+   |
+LL |     type Foo = impl std::fmt::Debug;
+   |                ^^^^^^^^^^^^^^^^^^^^
+note: required by a bound in `is_send`
+  --> $DIR/auto-trait-leakage2.rs:16:15
+   |
+LL | fn is_send<T: Send>(_: T) {}
+   |               ^^^^ required by this bound in `is_send`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/auto-trait-leakage3.rs b/src/test/ui/type-alias-impl-trait/auto-trait-leakage3.rs
new file mode 100644
index 000000000..5fb7a9473
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/auto-trait-leakage3.rs
@@ -0,0 +1,21 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+// FIXME This should compile, but it currently doesn't
+
+mod m {
+    type Foo = impl std::fmt::Debug;
+    //~^ ERROR: cycle detected when computing type of `m::Foo::{opaque#0}` [E0391]
+
+    pub fn foo() -> Foo {
+        22_u32
+    }
+
+    pub fn bar() {
+        is_send(foo());
+    }
+
+    fn is_send<T: Send>(_: T) {}
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/auto-trait-leakage3.stderr b/src/test/ui/type-alias-impl-trait/auto-trait-leakage3.stderr
new file mode 100644
index 000000000..1e9a45aac
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/auto-trait-leakage3.stderr
@@ -0,0 +1,22 @@
+error[E0391]: cycle detected when computing type of `m::Foo::{opaque#0}`
+  --> $DIR/auto-trait-leakage3.rs:7:16
+   |
+LL |     type Foo = impl std::fmt::Debug;
+   |                ^^^^^^^^^^^^^^^^^^^^
+   |
+note: ...which requires type-checking `m::bar`...
+  --> $DIR/auto-trait-leakage3.rs:15:9
+   |
+LL |         is_send(foo());
+   |         ^^^^^^^
+   = note: ...which requires evaluating trait selection obligation `m::Foo: core::marker::Send`...
+   = note: ...which again requires computing type of `m::Foo::{opaque#0}`, completing the cycle
+note: cycle used when checking item types in module `m`
+  --> $DIR/auto-trait-leakage3.rs:6:1
+   |
+LL | mod m {
+   | ^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0391`.
diff --git a/src/test/ui/type-alias-impl-trait/auxiliary/collect_hidden_types.rs b/src/test/ui/type-alias-impl-trait/auxiliary/collect_hidden_types.rs
new file mode 100644
index 000000000..75d20a6fe
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/auxiliary/collect_hidden_types.rs
@@ -0,0 +1,21 @@
+#![feature(type_alias_impl_trait)]
+
+// edition:2018
+
+use std::future::Future;
+
+pub trait Service<Request> {
+    type Future: Future<Output = ()>;
+    fn call(&mut self, req: Request) -> Self::Future;
+}
+
+// NOTE: the pub(crate) here is critical
+pub(crate) fn new() -> () {}
+
+pub struct A;
+impl Service<()> for A {
+    type Future = impl Future<Output = ()>;
+    fn call(&mut self, _: ()) -> Self::Future {
+        async { new() }
+    }
+}
diff --git a/src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice.rs b/src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice.rs
new file mode 100644
index 000000000..e7bca2231
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice.rs
@@ -0,0 +1,10 @@
+// Crate that exports an opaque `impl Trait` type. Used for testing cross-crate.
+
+#![crate_type = "rlib"]
+#![feature(type_alias_impl_trait)]
+
+pub type Foo = impl std::fmt::Debug;
+
+pub fn foo() -> Foo {
+    5
+}
diff --git a/src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice2.rs b/src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice2.rs
new file mode 100644
index 000000000..119f7df1f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice2.rs
@@ -0,0 +1,20 @@
+// Crate that exports an opaque `impl Trait` type. Used for testing cross-crate.
+
+#![crate_type = "rlib"]
+#![feature(type_alias_impl_trait)]
+
+pub trait View {
+    type Tmp: Iterator<Item = u32>;
+
+    fn test(&self) -> Self::Tmp;
+}
+
+pub struct X;
+
+impl View for X {
+    type Tmp = impl Iterator<Item = u32>;
+
+    fn test(&self) -> Self::Tmp {
+        vec![1, 2, 3].into_iter()
+    }
+}
diff --git a/src/test/ui/type-alias-impl-trait/auxiliary/foreign-crate.rs b/src/test/ui/type-alias-impl-trait/auxiliary/foreign-crate.rs
new file mode 100644
index 000000000..52802dd8f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/auxiliary/foreign-crate.rs
@@ -0,0 +1,2 @@
+pub trait ForeignTrait {}
+pub struct ForeignType<T>(pub T);
diff --git a/src/test/ui/type-alias-impl-trait/bound_reduction.rs b/src/test/ui/type-alias-impl-trait/bound_reduction.rs
new file mode 100644
index 000000000..b9b50f0b7
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/bound_reduction.rs
@@ -0,0 +1,19 @@
+// build-pass (FIXME(62277): could be check-pass?)
+
+#![allow(warnings)]
+#![feature(type_alias_impl_trait)]
+
+fn main() {
+}
+
+type Foo<V> = impl std::fmt::Debug;
+
+trait Trait<U> {}
+
+fn foo_desugared<T: Trait<[u32; {
+    #[no_mangle]
+    static FOO: usize = 42;
+    3
+}]>>(_: T) -> Foo<T> {
+    (42, std::marker::PhantomData::<T>)
+}
diff --git a/src/test/ui/type-alias-impl-trait/bound_reduction2.rs b/src/test/ui/type-alias-impl-trait/bound_reduction2.rs
new file mode 100644
index 000000000..4d2890b5d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/bound_reduction2.rs
@@ -0,0 +1,18 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+trait TraitWithAssoc {
+    type Assoc;
+}
+
+type Foo<V> = impl Trait<V>;
+
+trait Trait<U> {}
+
+impl<W> Trait<W> for () {}
+
+fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T::Assoc> {
+    ()
+    //~^ ERROR non-defining opaque type use
+}
diff --git a/src/test/ui/type-alias-impl-trait/bound_reduction2.stderr b/src/test/ui/type-alias-impl-trait/bound_reduction2.stderr
new file mode 100644
index 000000000..c405b1f6a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/bound_reduction2.stderr
@@ -0,0 +1,14 @@
+error: non-defining opaque type use in defining scope
+  --> $DIR/bound_reduction2.rs:16:5
+   |
+LL |     ()
+   |     ^^
+   |
+note: used non-generic type `<T as TraitWithAssoc>::Assoc` for generic parameter
+  --> $DIR/bound_reduction2.rs:9:10
+   |
+LL | type Foo<V> = impl Trait<V>;
+   |          ^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/bounds-are-checked-2.rs b/src/test/ui/type-alias-impl-trait/bounds-are-checked-2.rs
new file mode 100644
index 000000000..55b4dc8dc
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/bounds-are-checked-2.rs
@@ -0,0 +1,19 @@
+// Make sure that we check that impl trait types implement the traits that they
+// claim to.
+
+#![feature(type_alias_impl_trait)]
+
+type X<T> = impl Clone;
+
+fn f<T: Clone>(t: T) -> X<T> {
+    t
+    //~^ ERROR the trait bound `T: Clone` is not satisfied
+}
+
+fn g<T>(o: Option<X<T>>) -> Option<X<T>> {
+    o.clone()
+}
+
+fn main() {
+    g(None::<X<&mut ()>>);
+}
diff --git a/src/test/ui/type-alias-impl-trait/bounds-are-checked-2.stderr b/src/test/ui/type-alias-impl-trait/bounds-are-checked-2.stderr
new file mode 100644
index 000000000..8678e9b33
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/bounds-are-checked-2.stderr
@@ -0,0 +1,14 @@
+error[E0277]: the trait bound `T: Clone` is not satisfied
+  --> $DIR/bounds-are-checked-2.rs:9:5
+   |
+LL |     t
+   |     ^ the trait `Clone` is not implemented for `T`
+   |
+help: consider restricting type parameter `T`
+   |
+LL | type X<T: std::clone::Clone> = impl Clone;
+   |         +++++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/bounds-are-checked.rs b/src/test/ui/type-alias-impl-trait/bounds-are-checked.rs
new file mode 100644
index 000000000..83d22161e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/bounds-are-checked.rs
@@ -0,0 +1,24 @@
+// Make sure that we check that impl trait types implement the traits that they
+// claim to.
+
+#![feature(type_alias_impl_trait)]
+
+type X<'a> = impl Into<&'static str> + From<&'a str>;
+
+fn f<'a: 'static>(t: &'a str) -> X<'a> {
+    //~^ WARNING unnecessary lifetime parameter
+    t
+    //~^ ERROR non-defining opaque type use
+}
+
+fn extend_lt<'a>(o: &'a str) -> &'static str {
+    X::<'_>::from(o).into()
+}
+
+fn main() {
+    let r = {
+        let s = "abcdef".to_string();
+        extend_lt(&s)
+    };
+    println!("{}", r);
+}
diff --git a/src/test/ui/type-alias-impl-trait/bounds-are-checked.stderr b/src/test/ui/type-alias-impl-trait/bounds-are-checked.stderr
new file mode 100644
index 000000000..920eef11d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/bounds-are-checked.stderr
@@ -0,0 +1,19 @@
+warning: unnecessary lifetime parameter `'a`
+  --> $DIR/bounds-are-checked.rs:8:6
+   |
+LL | fn f<'a: 'static>(t: &'a str) -> X<'a> {
+   |      ^^
+   |
+   = help: you can use the `'static` lifetime directly, in place of `'a`
+
+error: non-defining opaque type use in defining scope
+  --> $DIR/bounds-are-checked.rs:10:5
+   |
+LL | type X<'a> = impl Into<&'static str> + From<&'a str>;
+   |        -- cannot use static lifetime; use a bound lifetime instead or remove the lifetime parameter from the opaque type
+...
+LL |     t
+   |     ^
+
+error: aborting due to previous error; 1 warning emitted
+
diff --git a/src/test/ui/type-alias-impl-trait/closures_in_branches.rs b/src/test/ui/type-alias-impl-trait/closures_in_branches.rs
new file mode 100644
index 000000000..7bb490bbe
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/closures_in_branches.rs
@@ -0,0 +1,31 @@
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl std::ops::FnOnce(String) -> usize;
+
+fn foo(b: bool) -> Foo {
+    if b {
+        |x| x.len() //~ ERROR type annotations needed
+    } else {
+        panic!()
+    }
+}
+
+
+type Foo1 = impl std::ops::FnOnce(String) -> usize;
+fn foo1(b: bool) -> Foo1 {
+    |x| x.len()
+}
+
+fn bar(b: bool) -> impl std::ops::FnOnce(String) -> usize {
+    if b {
+        |x| x.len() //~ ERROR type annotations needed
+    } else {
+        panic!()
+    }
+}
+
+fn bar1(b: bool) -> impl std::ops::FnOnce(String) -> usize {
+    |x| x.len()
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/closures_in_branches.stderr b/src/test/ui/type-alias-impl-trait/closures_in_branches.stderr
new file mode 100644
index 000000000..48b7946ea
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/closures_in_branches.stderr
@@ -0,0 +1,25 @@
+error[E0282]: type annotations needed
+  --> $DIR/closures_in_branches.rs:7:10
+   |
+LL |         |x| x.len()
+   |          ^  - type must be known at this point
+   |
+help: consider giving this closure parameter an explicit type
+   |
+LL |         |x: _| x.len()
+   |           +++
+
+error[E0282]: type annotations needed
+  --> $DIR/closures_in_branches.rs:21:10
+   |
+LL |         |x| x.len()
+   |          ^  - type must be known at this point
+   |
+help: consider giving this closure parameter an explicit type
+   |
+LL |         |x: _| x.len()
+   |           +++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type-alias-impl-trait/coherence.rs b/src/test/ui/type-alias-impl-trait/coherence.rs
new file mode 100644
index 000000000..98ac215ad
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/coherence.rs
@@ -0,0 +1,17 @@
+// aux-build:foreign-crate.rs
+#![feature(type_alias_impl_trait)]
+
+extern crate foreign_crate;
+
+trait LocalTrait {}
+impl<T> LocalTrait for foreign_crate::ForeignType<T> {}
+
+type AliasOfForeignType<T> = impl LocalTrait;
+fn use_alias<T>(val: T) -> AliasOfForeignType<T> {
+    foreign_crate::ForeignType(val)
+}
+
+impl<T> foreign_crate::ForeignTrait for AliasOfForeignType<T> {}
+//~^ ERROR cannot implement trait on type alias impl trait
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/coherence.stderr b/src/test/ui/type-alias-impl-trait/coherence.stderr
new file mode 100644
index 000000000..3ce25d94f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/coherence.stderr
@@ -0,0 +1,14 @@
+error: cannot implement trait on type alias impl trait
+  --> $DIR/coherence.rs:14:41
+   |
+LL | impl<T> foreign_crate::ForeignTrait for AliasOfForeignType<T> {}
+   |                                         ^^^^^^^^^^^^^^^^^^^^^
+   |
+note: type alias impl trait defined here
+  --> $DIR/coherence.rs:9:30
+   |
+LL | type AliasOfForeignType<T> = impl LocalTrait;
+   |                              ^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/collect_hidden_types.rs b/src/test/ui/type-alias-impl-trait/collect_hidden_types.rs
new file mode 100644
index 000000000..e78f178e4
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/collect_hidden_types.rs
@@ -0,0 +1,22 @@
+// aux-build:collect_hidden_types.rs
+use collect_hidden_types::Service;
+use std::future::Future;
+use std::pin::Pin;
+use std::task::Context;
+
+// build-pass
+
+// edition:2018
+
+extern crate collect_hidden_types;
+
+fn broken(mut a: collect_hidden_types::A, cx: &mut Context<'_>) {
+    let mut fut = a.call(());
+    let _ = unsafe { Pin::new_unchecked(&mut fut) }.poll(cx);
+}
+
+pub async fn meeb(cx: &mut Context<'_>) {
+    broken(collect_hidden_types::A, cx);
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/constrain_inputs.rs b/src/test/ui/type-alias-impl-trait/constrain_inputs.rs
new file mode 100644
index 000000000..c32174288
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/constrain_inputs.rs
@@ -0,0 +1,17 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+mod foo {
+    type Ty<'a> = impl Sized;
+    fn defining(s: &str) -> Ty<'_> { s }
+    fn execute(ty: Ty<'_>) -> &str { todo!() }
+}
+
+mod bar {
+    type Ty<'a> = impl FnOnce() -> &'a str;
+    fn defining(s: &str) -> Ty<'_> { move || s }
+    fn execute(ty: Ty<'_>) -> &str { ty() }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/cross_crate_ice.rs b/src/test/ui/type-alias-impl-trait/cross_crate_ice.rs
new file mode 100644
index 000000000..c30608176
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/cross_crate_ice.rs
@@ -0,0 +1,16 @@
+// aux-build:cross_crate_ice.rs
+// build-pass (FIXME(62277): could be check-pass?)
+
+extern crate cross_crate_ice;
+
+struct Bar(cross_crate_ice::Foo);
+
+impl Bar {
+    fn zero(&self) -> &cross_crate_ice::Foo {
+        &self.0
+    }
+}
+
+fn main() {
+    let _ = cross_crate_ice::foo();
+}
diff --git a/src/test/ui/type-alias-impl-trait/cross_crate_ice2.rs b/src/test/ui/type-alias-impl-trait/cross_crate_ice2.rs
new file mode 100644
index 000000000..3a7e49026
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/cross_crate_ice2.rs
@@ -0,0 +1,11 @@
+// aux-build:cross_crate_ice2.rs
+// build-pass (FIXME(62277): could be check-pass?)
+
+extern crate cross_crate_ice2;
+
+use cross_crate_ice2::View;
+
+fn main() {
+    let v = cross_crate_ice2::X;
+    v.test();
+}
diff --git a/src/test/ui/type-alias-impl-trait/cross_inference.rs b/src/test/ui/type-alias-impl-trait/cross_inference.rs
new file mode 100644
index 000000000..dafaf40a6
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/cross_inference.rs
@@ -0,0 +1,10 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+fn main() {
+    type T = impl Copy;
+    let foo: T = (1u32, 2u32);
+    let x: (_, _) = foo;
+    println!("{:?}", x);
+}
diff --git a/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.rs b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.rs
new file mode 100644
index 000000000..811832848
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.rs
@@ -0,0 +1,8 @@
+// compile-flags: --edition=2021
+#![feature(type_alias_impl_trait)]
+
+fn main() {
+    type T = impl Copy; //~ ERROR unconstrained opaque type
+    let foo: T = (1u32, 2u32);
+    let (a, b): (u32, u32) = foo;
+}
diff --git a/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.stderr b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.stderr
new file mode 100644
index 000000000..03b172e6d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.stderr
@@ -0,0 +1,10 @@
+error: unconstrained opaque type
+  --> $DIR/cross_inference_pattern_bug.rs:5:14
+   |
+LL |     type T = impl Copy;
+   |              ^^^^^^^^^
+   |
+   = note: `T` must be used in combination with a concrete type within the same module
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug_no_type.rs b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug_no_type.rs
new file mode 100644
index 000000000..328096d44
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug_no_type.rs
@@ -0,0 +1,13 @@
+// known-bug: #96572
+// compile-flags: --edition=2021 --crate-type=lib
+// rustc-env:RUST_BACKTRACE=0
+
+// tracked in https://github.com/rust-lang/rust/issues/96572
+
+#![feature(type_alias_impl_trait)]
+
+fn main() {
+    type T = impl Copy;  // error: unconstrained opaque type
+    let foo: T = (1u32, 2u32);
+    let (a, b) = foo; // removing this line makes the code compile
+}
diff --git a/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug_no_type.stderr b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug_no_type.stderr
new file mode 100644
index 000000000..8aa1f4956
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug_no_type.stderr
@@ -0,0 +1,10 @@
+error: unconstrained opaque type
+  --> $DIR/cross_inference_pattern_bug_no_type.rs:10:14
+   |
+LL |     type T = impl Copy;  // error: unconstrained opaque type
+   |              ^^^^^^^^^
+   |
+   = note: `T` must be used in combination with a concrete type within the same module
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/cross_inference_rpit.rs b/src/test/ui/type-alias-impl-trait/cross_inference_rpit.rs
new file mode 100644
index 000000000..f6affbf17
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/cross_inference_rpit.rs
@@ -0,0 +1,14 @@
+// check-pass
+
+fn foo(b: bool) -> impl Copy {
+    if b {
+        return (5,6)
+    }
+    let x: (_, _) = foo(true);
+    println!("{:?}", x);
+    (1u32, 2u32)
+}
+
+fn main() {
+    foo(false);
+}
diff --git a/src/test/ui/type-alias-impl-trait/declared_but_never_defined.rs b/src/test/ui/type-alias-impl-trait/declared_but_never_defined.rs
new file mode 100644
index 000000000..6febd0715
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/declared_but_never_defined.rs
@@ -0,0 +1,6 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+// declared but never defined
+type Bar = impl std::fmt::Debug; //~ ERROR unconstrained opaque type
diff --git a/src/test/ui/type-alias-impl-trait/declared_but_never_defined.stderr b/src/test/ui/type-alias-impl-trait/declared_but_never_defined.stderr
new file mode 100644
index 000000000..60bc24320
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/declared_but_never_defined.stderr
@@ -0,0 +1,10 @@
+error: unconstrained opaque type
+  --> $DIR/declared_but_never_defined.rs:6:12
+   |
+LL | type Bar = impl std::fmt::Debug;
+   |            ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `Bar` must be used in combination with a concrete type within the same module
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/declared_but_not_defined_in_scope.rs b/src/test/ui/type-alias-impl-trait/declared_but_not_defined_in_scope.rs
new file mode 100644
index 000000000..5bda5f0fc
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/declared_but_not_defined_in_scope.rs
@@ -0,0 +1,13 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+mod boo {
+    // declared in module but not defined inside of it
+    pub type Boo = impl ::std::fmt::Debug; //~ ERROR unconstrained opaque type
+}
+
+fn bomp() -> boo::Boo {
+    ""
+    //~^ mismatched types
+}
diff --git a/src/test/ui/type-alias-impl-trait/declared_but_not_defined_in_scope.stderr b/src/test/ui/type-alias-impl-trait/declared_but_not_defined_in_scope.stderr
new file mode 100644
index 000000000..fbfa0ccf1
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/declared_but_not_defined_in_scope.stderr
@@ -0,0 +1,25 @@
+error: unconstrained opaque type
+  --> $DIR/declared_but_not_defined_in_scope.rs:7:20
+   |
+LL |     pub type Boo = impl ::std::fmt::Debug;
+   |                    ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `Boo` must be used in combination with a concrete type within the same module
+
+error[E0308]: mismatched types
+  --> $DIR/declared_but_not_defined_in_scope.rs:11:5
+   |
+LL |     pub type Boo = impl ::std::fmt::Debug;
+   |                    ---------------------- the expected opaque type
+...
+LL | fn bomp() -> boo::Boo {
+   |              -------- expected `Boo` because of return type
+LL |     ""
+   |     ^^ expected opaque type, found `&str`
+   |
+   = note: expected opaque type `Boo`
+                found reference `&'static str`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type-alias-impl-trait/defining-use-submodule.rs b/src/test/ui/type-alias-impl-trait/defining-use-submodule.rs
new file mode 100644
index 000000000..8b51f5571
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/defining-use-submodule.rs
@@ -0,0 +1,23 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+// test that the type alias impl trait defining use is in a submodule
+
+fn main() {}
+
+type Foo = impl std::fmt::Display;
+type Bar = impl std::fmt::Display;
+
+mod foo {
+    pub fn foo() -> super::Foo {
+        "foo"
+    }
+
+    pub mod bar {
+        pub fn bar() -> crate::Bar {
+            1
+        }
+    }
+}
diff --git a/src/test/ui/type-alias-impl-trait/different_defining_uses.rs b/src/test/ui/type-alias-impl-trait/different_defining_uses.rs
new file mode 100644
index 000000000..4505c4d95
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/different_defining_uses.rs
@@ -0,0 +1,15 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+// two definitions with different types
+type Foo = impl std::fmt::Debug;
+
+fn foo() -> Foo {
+    ""
+}
+
+fn bar() -> Foo {
+    42i32
+    //~^ ERROR concrete type differs from previous
+}
diff --git a/src/test/ui/type-alias-impl-trait/different_defining_uses.stderr b/src/test/ui/type-alias-impl-trait/different_defining_uses.stderr
new file mode 100644
index 000000000..a8b4cd7af
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/different_defining_uses.stderr
@@ -0,0 +1,14 @@
+error: concrete type differs from previous defining opaque type use
+  --> $DIR/different_defining_uses.rs:13:5
+   |
+LL |     42i32
+   |     ^^^^^ expected `&'static str`, got `i32`
+   |
+note: previous use here
+  --> $DIR/different_defining_uses.rs:9:5
+   |
+LL |     ""
+   |     ^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/different_defining_uses_never_type.rs b/src/test/ui/type-alias-impl-trait/different_defining_uses_never_type.rs
new file mode 100644
index 000000000..7740f774e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/different_defining_uses_never_type.rs
@@ -0,0 +1,18 @@
+#![feature(type_alias_impl_trait)]
+// check-pass
+fn main() {}
+
+// two definitions with different types
+type Foo = impl std::fmt::Debug;
+
+fn foo() -> Foo {
+    ""
+}
+
+fn bar() -> Foo {
+    panic!()
+}
+
+fn boo() -> Foo {
+    loop {}
+}
diff --git a/src/test/ui/type-alias-impl-trait/different_defining_uses_never_type2.rs b/src/test/ui/type-alias-impl-trait/different_defining_uses_never_type2.rs
new file mode 100644
index 000000000..8549687ea
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/different_defining_uses_never_type2.rs
@@ -0,0 +1,44 @@
+// build-pass (FIXME(62277): could be check-pass?)
+
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+// two definitions with different types
+type Foo = impl std::fmt::Debug;
+
+fn foo() -> Foo {
+    ""
+}
+
+fn bar(arg: bool) -> Foo {
+    if arg {
+        panic!()
+    } else {
+        "bar"
+    }
+}
+
+fn boo(arg: bool) -> Foo {
+    if arg {
+        loop {}
+    } else {
+        "boo"
+    }
+}
+
+fn bar2(arg: bool) -> Foo {
+    if arg {
+        "bar2"
+    } else {
+        panic!()
+    }
+}
+
+fn boo2(arg: bool) -> Foo {
+    if arg {
+        "boo2"
+    } else {
+        loop {}
+    }
+}
diff --git a/src/test/ui/type-alias-impl-trait/different_lifetimes_defining_uses.rs b/src/test/ui/type-alias-impl-trait/different_lifetimes_defining_uses.rs
new file mode 100644
index 000000000..4f424b8c6
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/different_lifetimes_defining_uses.rs
@@ -0,0 +1,15 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+type OneLifetime<'a, 'b> = impl std::fmt::Debug;
+
+fn foo<'a, 'b>(a: &'a u32, b: &'b u32) -> OneLifetime<'a, 'b> {
+    a
+}
+
+fn bar<'a, 'b>(a: &'a u32, b: &'b u32) -> OneLifetime<'a, 'b> {
+    b
+    //~^ ERROR: concrete type differs from previous defining opaque type use
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/different_lifetimes_defining_uses.stderr b/src/test/ui/type-alias-impl-trait/different_lifetimes_defining_uses.stderr
new file mode 100644
index 000000000..0c50a84e8
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/different_lifetimes_defining_uses.stderr
@@ -0,0 +1,14 @@
+error: concrete type differs from previous defining opaque type use
+  --> $DIR/different_lifetimes_defining_uses.rs:11:5
+   |
+LL |     b
+   |     ^ expected `&'a u32`, got `&'b u32`
+   |
+note: previous use here
+  --> $DIR/different_lifetimes_defining_uses.rs:7:5
+   |
+LL |     a
+   |     ^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/fallback.rs b/src/test/ui/type-alias-impl-trait/fallback.rs
new file mode 100644
index 000000000..d8cf7d71f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/fallback.rs
@@ -0,0 +1,28 @@
+// Tests that we correctly handle opaque types being used opaquely,
+// even within their defining scope.
+//
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl Copy;
+
+enum Wrapper<T> {
+    First(T),
+    Second
+}
+
+// This method constrains `Foo` to be `bool`
+fn constrained_foo() -> Foo {
+    true
+}
+
+
+// This method does not constrain `Foo`.
+// Per RFC 2071, function bodies may either
+// fully constrain an opaque type, or place no
+// constraints on it.
+fn unconstrained_foo() -> Wrapper<Foo> {
+    Wrapper::Second
+    //~^ ERROR: type annotations needed
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/fallback.stderr b/src/test/ui/type-alias-impl-trait/fallback.stderr
new file mode 100644
index 000000000..e767bfdb0
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/fallback.stderr
@@ -0,0 +1,17 @@
+error[E0283]: type annotations needed
+  --> $DIR/fallback.rs:24:5
+   |
+LL | fn unconstrained_foo() -> Wrapper<Foo> {
+   |                           ------------ type must be known at this point
+LL |     Wrapper::Second
+   |     ^^^^^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the enum `Wrapper`
+   |
+   = note: cannot satisfy `_: Copy`
+help: consider specifying the generic argument
+   |
+LL |     Wrapper::<T>::Second
+   |            +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0283`.
diff --git a/src/test/ui/type-alias-impl-trait/field-types.rs b/src/test/ui/type-alias-impl-trait/field-types.rs
new file mode 100644
index 000000000..d99ed5812
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/field-types.rs
@@ -0,0 +1,18 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+// check-pass
+
+use std::fmt::Debug;
+
+type Foo = impl Debug;
+
+struct Bar {
+    foo: Foo,
+}
+
+fn bar() -> Bar {
+    Bar { foo: "foo" }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/future.rs b/src/test/ui/type-alias-impl-trait/future.rs
new file mode 100644
index 000000000..56323216e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/future.rs
@@ -0,0 +1,22 @@
+#![feature(type_alias_impl_trait)]
+
+// edition:2021
+// compile-flags: --crate-type=lib
+
+use std::future::Future;
+
+trait Bar {
+    fn bar(&self);
+}
+
+type FooFuture<B> = impl Future<Output = ()>;
+
+fn foo<B: Bar>(bar: B) -> FooFuture<B> {
+    async move { bar.bar() }
+    //~^ ERROR: the trait bound `B: Bar` is not satisfied
+}
+
+pub fn mainish(ctx: &mut std::task::Context) {
+    let boom: FooFuture<u32> = unsafe { core::mem::zeroed() };
+    Box::pin(boom).as_mut().poll(ctx);
+}
diff --git a/src/test/ui/type-alias-impl-trait/future.stderr b/src/test/ui/type-alias-impl-trait/future.stderr
new file mode 100644
index 000000000..7e76c120a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/future.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the trait bound `B: Bar` is not satisfied
+  --> $DIR/future.rs:15:5
+   |
+LL |     async move { bar.bar() }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Bar` is not implemented for `B`
+   |
+note: required by a bound in `foo`
+  --> $DIR/future.rs:14:11
+   |
+LL | fn foo<B: Bar>(bar: B) -> FooFuture<B> {
+   |           ^^^ required by this bound in `foo`
+help: consider restricting type parameter `B`
+   |
+LL | type FooFuture<B: Bar> = impl Future<Output = ()>;
+   |                 +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/generic_different_defining_uses.rs b/src/test/ui/type-alias-impl-trait/generic_different_defining_uses.rs
new file mode 100644
index 000000000..8b683ad28
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_different_defining_uses.rs
@@ -0,0 +1,14 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+type MyIter<T> = impl Iterator<Item = T>;
+
+fn my_iter<T>(t: T) -> MyIter<T> {
+    std::iter::once(t)
+}
+
+fn my_iter2<T>(t: T) -> MyIter<T> {
+    Some(t).into_iter()
+    //~^ ERROR concrete type differs from previous
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_different_defining_uses.stderr b/src/test/ui/type-alias-impl-trait/generic_different_defining_uses.stderr
new file mode 100644
index 000000000..47ac33462
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_different_defining_uses.stderr
@@ -0,0 +1,14 @@
+error: concrete type differs from previous defining opaque type use
+  --> $DIR/generic_different_defining_uses.rs:12:5
+   |
+LL |     Some(t).into_iter()
+   |     ^^^^^^^^^^^^^^^^^^^ expected `std::iter::Once<T>`, got `std::option::IntoIter<T>`
+   |
+note: previous use here
+  --> $DIR/generic_different_defining_uses.rs:8:5
+   |
+LL |     std::iter::once(t)
+   |     ^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_lifetime_param.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_lifetime_param.rs
new file mode 100644
index 000000000..c9b9e128f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_lifetime_param.rs
@@ -0,0 +1,11 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+type Two<'a, 'b> = impl std::fmt::Debug;
+
+
+fn one<'a>(t: &'a ()) -> Two<'a, 'a> {
+    t
+    //~^ ERROR non-defining opaque type use
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_lifetime_param.stderr b/src/test/ui/type-alias-impl-trait/generic_duplicate_lifetime_param.stderr
new file mode 100644
index 000000000..222aaea78
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_lifetime_param.stderr
@@ -0,0 +1,14 @@
+error: non-defining opaque type use in defining scope
+  --> $DIR/generic_duplicate_lifetime_param.rs:9:5
+   |
+LL |     t
+   |     ^
+   |
+note: lifetime used multiple times
+  --> $DIR/generic_duplicate_lifetime_param.rs:5:10
+   |
+LL | type Two<'a, 'b> = impl std::fmt::Debug;
+   |          ^^  ^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use.rs
new file mode 100644
index 000000000..093c1c231
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use.rs
@@ -0,0 +1,28 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+// test that unused generic parameters are ok
+type TwoTys<T, U> = impl Debug;
+
+type TwoLifetimes<'a, 'b> = impl Debug;
+
+type TwoConsts<const X: usize, const Y: usize> = impl Debug;
+
+
+fn one_ty<T: Debug>(t: T) -> TwoTys<T, T> {
+    t
+    //~^ ERROR non-defining opaque type use in defining scope
+}
+
+fn one_lifetime<'a>(t: &'a u32) -> TwoLifetimes<'a, 'a> {
+    t
+    //~^ ERROR non-defining opaque type use in defining scope
+}
+
+fn one_const<const N: usize>(t: *mut [u8; N]) -> TwoConsts<N, N> {
+    t
+    //~^ ERROR non-defining opaque type use in defining scope
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use.stderr b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use.stderr
new file mode 100644
index 000000000..b2edcc552
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use.stderr
@@ -0,0 +1,38 @@
+error: non-defining opaque type use in defining scope
+  --> $DIR/generic_duplicate_param_use.rs:16:5
+   |
+LL |     t
+   |     ^
+   |
+note: type used multiple times
+  --> $DIR/generic_duplicate_param_use.rs:8:13
+   |
+LL | type TwoTys<T, U> = impl Debug;
+   |             ^  ^
+
+error: non-defining opaque type use in defining scope
+  --> $DIR/generic_duplicate_param_use.rs:21:5
+   |
+LL |     t
+   |     ^
+   |
+note: lifetime used multiple times
+  --> $DIR/generic_duplicate_param_use.rs:10:19
+   |
+LL | type TwoLifetimes<'a, 'b> = impl Debug;
+   |                   ^^  ^^
+
+error: non-defining opaque type use in defining scope
+  --> $DIR/generic_duplicate_param_use.rs:26:5
+   |
+LL |     t
+   |     ^
+   |
+note: constant used multiple times
+  --> $DIR/generic_duplicate_param_use.rs:12:16
+   |
+LL | type TwoConsts<const X: usize, const Y: usize> = impl Debug;
+   |                ^^^^^^^^^^^^^^  ^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use10.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use10.rs
new file mode 100644
index 000000000..c17d595db
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use10.rs
@@ -0,0 +1,12 @@
+// check-pass
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+type Two<T: Debug, U> = impl Debug;
+
+fn two<T: Debug, U: Debug>(t: T, _: U) -> Two<T, U> {
+    (t, 4u32)
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use2.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use2.rs
new file mode 100644
index 000000000..201535efe
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use2.rs
@@ -0,0 +1,13 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+// test that unused generic parameters are ok
+type Two<T, U> = impl Debug;
+
+fn two<T: Debug, U>(t: T, _: U) -> Two<T, U> {
+    t
+    //~^ ERROR `T` doesn't implement `Debug`
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use2.stderr b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use2.stderr
new file mode 100644
index 000000000..3dbfff745
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use2.stderr
@@ -0,0 +1,14 @@
+error[E0277]: `T` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use2.rs:11:5
+   |
+LL |     t
+   |     ^ `T` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+help: consider restricting type parameter `T`
+   |
+LL | type Two<T: std::fmt::Debug, U> = impl Debug;
+   |           +++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use3.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use3.rs
new file mode 100644
index 000000000..e7a25fc72
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use3.rs
@@ -0,0 +1,18 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+// test that unused generic parameters are ok
+type Two<T, U> = impl Debug;
+
+fn two<T: Debug, U>(t: T, _: U) -> Two<T, U> {
+    t
+    //~^ ERROR `T` doesn't implement `Debug`
+}
+
+fn three<T, U: Debug>(_: T, u: U) -> Two<T, U> {
+    u
+    //~^ ERROR `U` doesn't implement `Debug`
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use3.stderr b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use3.stderr
new file mode 100644
index 000000000..7bec38220
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use3.stderr
@@ -0,0 +1,25 @@
+error[E0277]: `T` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use3.rs:11:5
+   |
+LL |     t
+   |     ^ `T` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+help: consider restricting type parameter `T`
+   |
+LL | type Two<T: std::fmt::Debug, U> = impl Debug;
+   |           +++++++++++++++++
+
+error[E0277]: `U` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use3.rs:16:5
+   |
+LL |     u
+   |     ^ `U` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+help: consider restricting type parameter `U`
+   |
+LL | type Two<T, U: std::fmt::Debug> = impl Debug;
+   |              +++++++++++++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use4.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use4.rs
new file mode 100644
index 000000000..d1e5a0f01
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use4.rs
@@ -0,0 +1,13 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+// test that unused generic parameters are ok
+type Two<T, U> = impl Debug;
+
+fn three<T, U: Debug>(_: T, u: U) -> Two<T, U> {
+    u
+    //~^ ERROR `U` doesn't implement `Debug`
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use4.stderr b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use4.stderr
new file mode 100644
index 000000000..21a5369d9
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use4.stderr
@@ -0,0 +1,14 @@
+error[E0277]: `U` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use4.rs:11:5
+   |
+LL |     u
+   |     ^ `U` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+help: consider restricting type parameter `U`
+   |
+LL | type Two<T, U: std::fmt::Debug> = impl Debug;
+   |              +++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use5.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use5.rs
new file mode 100644
index 000000000..3bd1dda63
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use5.rs
@@ -0,0 +1,20 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+// test that unused generic parameters are ok
+type Two<T, U> = impl Debug;
+
+fn two<T: Debug, U: Debug>(t: T, u: U) -> Two<T, U> {
+    (t, u)
+    //~^ ERROR `T` doesn't implement `Debug`
+    //~| ERROR `U` doesn't implement `Debug`
+}
+
+fn three<T: Debug, U: Debug>(t: T, u: U) -> Two<T, U> {
+    (u, t)
+    //~^ ERROR `T` doesn't implement `Debug`
+    //~| ERROR `U` doesn't implement `Debug`
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use5.stderr b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use5.stderr
new file mode 100644
index 000000000..2768f0c3a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use5.stderr
@@ -0,0 +1,51 @@
+error[E0277]: `T` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use5.rs:11:5
+   |
+LL |     (t, u)
+   |     ^^^^^^ `T` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(T, U)`
+help: consider restricting type parameter `T`
+   |
+LL | type Two<T: std::fmt::Debug, U> = impl Debug;
+   |           +++++++++++++++++
+
+error[E0277]: `U` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use5.rs:11:5
+   |
+LL |     (t, u)
+   |     ^^^^^^ `U` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(T, U)`
+help: consider restricting type parameter `U`
+   |
+LL | type Two<T, U: std::fmt::Debug> = impl Debug;
+   |              +++++++++++++++++
+
+error[E0277]: `U` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use5.rs:17:5
+   |
+LL |     (u, t)
+   |     ^^^^^^ `U` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(U, T)`
+help: consider restricting type parameter `U`
+   |
+LL | type Two<T, U: std::fmt::Debug> = impl Debug;
+   |              +++++++++++++++++
+
+error[E0277]: `T` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use5.rs:17:5
+   |
+LL |     (u, t)
+   |     ^^^^^^ `T` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(U, T)`
+help: consider restricting type parameter `T`
+   |
+LL | type Two<T: std::fmt::Debug, U> = impl Debug;
+   |           +++++++++++++++++
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use6.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use6.rs
new file mode 100644
index 000000000..5120925e5
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use6.rs
@@ -0,0 +1,19 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+// test that unused generic parameters are ok
+type Two<T, U> = impl Debug;
+
+fn two<T: Copy + Debug, U: Debug>(t: T, u: U) -> Two<T, U> {
+    (t, t)
+    //~^ ERROR `T` doesn't implement `Debug`
+}
+
+fn three<T: Copy + Debug, U: Debug>(t: T, u: U) -> Two<T, U> {
+    (u, t)
+    //~^ ERROR `T` doesn't implement `Debug`
+    //~| ERROR `U` doesn't implement `Debug`
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use6.stderr b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use6.stderr
new file mode 100644
index 000000000..c1712ca2e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use6.stderr
@@ -0,0 +1,39 @@
+error[E0277]: `T` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use6.rs:11:5
+   |
+LL |     (t, t)
+   |     ^^^^^^ `T` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(T, T)`
+help: consider restricting type parameter `T`
+   |
+LL | type Two<T: std::fmt::Debug, U> = impl Debug;
+   |           +++++++++++++++++
+
+error[E0277]: `U` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use6.rs:16:5
+   |
+LL |     (u, t)
+   |     ^^^^^^ `U` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(U, T)`
+help: consider restricting type parameter `U`
+   |
+LL | type Two<T, U: std::fmt::Debug> = impl Debug;
+   |              +++++++++++++++++
+
+error[E0277]: `T` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use6.rs:16:5
+   |
+LL |     (u, t)
+   |     ^^^^^^ `T` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(U, T)`
+help: consider restricting type parameter `T`
+   |
+LL | type Two<T: std::fmt::Debug, U> = impl Debug;
+   |           +++++++++++++++++
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use7.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use7.rs
new file mode 100644
index 000000000..feebf81ee
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use7.rs
@@ -0,0 +1,24 @@
+// check-pass
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+type Two<A: Debug, B> = impl Debug;
+
+fn two<T: Debug + Copy, U>(t: T, u: U) -> Two<T, U> {
+    (t, t)
+}
+
+fn three<T: Debug, U>(t: T, t2: T, u: U) -> Two<T, U> {
+    (t, t2)
+}
+
+fn four<T: Debug, U, V>(t: T, t2: T, u: U, v: V) -> Two<T, U> {
+    (t, t2)
+}
+
+fn five<X, Y: Debug>(x: X, y: Y, y2: Y) -> Two<Y, X> {
+    (y, y2)
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use8.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use8.rs
new file mode 100644
index 000000000..3a4b5047b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use8.rs
@@ -0,0 +1,17 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+type Two<T, U> = impl Debug;
+
+fn two<T: Debug, U: Debug>(t: T, _: U) -> Two<T, U> {
+    (t, 4u32)
+    //~^ ERROR `T` doesn't implement `Debug`
+}
+
+fn three<T: Debug, U: Debug>(_: T, u: U) -> Two<T, U> {
+    (u, 4u32)
+    //~^ ERROR `U` doesn't implement `Debug`
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use8.stderr b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use8.stderr
new file mode 100644
index 000000000..b83105c45
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use8.stderr
@@ -0,0 +1,27 @@
+error[E0277]: `T` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use8.rs:10:5
+   |
+LL |     (t, 4u32)
+   |     ^^^^^^^^^ `T` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(T, u32)`
+help: consider restricting type parameter `T`
+   |
+LL | type Two<T: std::fmt::Debug, U> = impl Debug;
+   |           +++++++++++++++++
+
+error[E0277]: `U` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use8.rs:15:5
+   |
+LL |     (u, 4u32)
+   |     ^^^^^^^^^ `U` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(U, u32)`
+help: consider restricting type parameter `U`
+   |
+LL | type Two<T, U: std::fmt::Debug> = impl Debug;
+   |              +++++++++++++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use9.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use9.rs
new file mode 100644
index 000000000..6afcdfe4d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use9.rs
@@ -0,0 +1,25 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+type Two<A, B> = impl Debug;
+
+trait Foo {
+    type Bar: Debug;
+    const BAR: Self::Bar;
+}
+
+fn two<T: Debug + Foo, U: Debug>(t: T, u: U) -> Two<T, U> {
+    (t, u, T::BAR)
+    //~^ ERROR the trait bound `A: Foo` is not satisfied
+    //~| ERROR `A` doesn't implement `Debug`
+    //~| ERROR `B` doesn't implement `Debug`
+}
+
+fn three<T: Debug, U: Debug>(t: T, u: U) -> Two<T, U> {
+    (t, u, 42)
+    //~^ ERROR `A` doesn't implement `Debug`
+    //~| ERROR `B` doesn't implement `Debug`
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use9.stderr b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use9.stderr
new file mode 100644
index 000000000..50cf98273
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use9.stderr
@@ -0,0 +1,62 @@
+error[E0277]: the trait bound `A: Foo` is not satisfied
+  --> $DIR/generic_duplicate_param_use9.rs:15:5
+   |
+LL |     (t, u, T::BAR)
+   |     ^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `A`
+   |
+help: consider restricting type parameter `A`
+   |
+LL | type Two<A: Foo, B> = impl Debug;
+   |           +++++
+
+error[E0277]: `A` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use9.rs:15:5
+   |
+LL |     (t, u, T::BAR)
+   |     ^^^^^^^^^^^^^^ `A` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(A, B, _)`
+help: consider restricting type parameter `A`
+   |
+LL | type Two<A: std::fmt::Debug, B> = impl Debug;
+   |           +++++++++++++++++
+
+error[E0277]: `B` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use9.rs:15:5
+   |
+LL |     (t, u, T::BAR)
+   |     ^^^^^^^^^^^^^^ `B` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(A, B, _)`
+help: consider restricting type parameter `B`
+   |
+LL | type Two<A, B: std::fmt::Debug> = impl Debug;
+   |              +++++++++++++++++
+
+error[E0277]: `A` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use9.rs:22:5
+   |
+LL |     (t, u, 42)
+   |     ^^^^^^^^^^ `A` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(A, B, i32)`
+help: consider restricting type parameter `A`
+   |
+LL | type Two<A: std::fmt::Debug, B> = impl Debug;
+   |           +++++++++++++++++
+
+error[E0277]: `B` doesn't implement `Debug`
+  --> $DIR/generic_duplicate_param_use9.rs:22:5
+   |
+LL |     (t, u, 42)
+   |     ^^^^^^^^^^ `B` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(A, B, i32)`
+help: consider restricting type parameter `B`
+   |
+LL | type Two<A, B: std::fmt::Debug> = impl Debug;
+   |              +++++++++++++++++
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/generic_lifetime_param.rs b/src/test/ui/type-alias-impl-trait/generic_lifetime_param.rs
new file mode 100644
index 000000000..e109c38c9
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_lifetime_param.rs
@@ -0,0 +1,11 @@
+// build-pass (FIXME(62277): could be check-pass?)
+
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+type Region<'a> = impl std::fmt::Debug;
+
+fn region<'b>(a: &'b ()) -> Region<'b> {
+    a
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_nondefining_use.rs b/src/test/ui/type-alias-impl-trait/generic_nondefining_use.rs
new file mode 100644
index 000000000..f39741a6a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_nondefining_use.rs
@@ -0,0 +1,29 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+type OneTy<T> = impl Debug;
+
+type OneLifetime<'a> = impl Debug;
+
+type OneConst<const X: usize> = impl Debug;
+
+
+// Not defining uses, because they doesn't define *all* possible generics.
+
+fn concrete_ty() -> OneTy<u32> {
+    5u32
+    //~^ ERROR non-defining opaque type use in defining scope
+}
+
+fn concrete_lifetime() -> OneLifetime<'static> {
+    6u32
+    //~^ ERROR non-defining opaque type use in defining scope
+}
+
+fn concrete_const() -> OneConst<{ 123 }> {
+    7u32
+    //~^ ERROR non-defining opaque type use in defining scope
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_nondefining_use.stderr b/src/test/ui/type-alias-impl-trait/generic_nondefining_use.stderr
new file mode 100644
index 000000000..e7565525a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_nondefining_use.stderr
@@ -0,0 +1,35 @@
+error: non-defining opaque type use in defining scope
+  --> $DIR/generic_nondefining_use.rs:17:5
+   |
+LL |     5u32
+   |     ^^^^
+   |
+note: used non-generic type `u32` for generic parameter
+  --> $DIR/generic_nondefining_use.rs:7:12
+   |
+LL | type OneTy<T> = impl Debug;
+   |            ^
+
+error: non-defining opaque type use in defining scope
+  --> $DIR/generic_nondefining_use.rs:22:5
+   |
+LL | type OneLifetime<'a> = impl Debug;
+   |                  -- cannot use static lifetime; use a bound lifetime instead or remove the lifetime parameter from the opaque type
+...
+LL |     6u32
+   |     ^^^^
+
+error: non-defining opaque type use in defining scope
+  --> $DIR/generic_nondefining_use.rs:27:5
+   |
+LL |     7u32
+   |     ^^^^
+   |
+note: used non-generic constant `123` for generic parameter
+  --> $DIR/generic_nondefining_use.rs:11:15
+   |
+LL | type OneConst<const X: usize> = impl Debug;
+   |               ^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
diff --git a/src/test/ui/type-alias-impl-trait/generic_not_used.rs b/src/test/ui/type-alias-impl-trait/generic_not_used.rs
new file mode 100644
index 000000000..c70f473cf
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_not_used.rs
@@ -0,0 +1,11 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+type WrongGeneric<T: 'static> = impl 'static;
+//~^ ERROR: at least one trait must be specified
+
+fn wrong_generic<U: 'static, V: 'static>(_: U, v: V) -> WrongGeneric<U> {
+    v
+    //~^ ERROR type parameter `V` is part of concrete type but not used in parameter list
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_not_used.stderr b/src/test/ui/type-alias-impl-trait/generic_not_used.stderr
new file mode 100644
index 000000000..fd720239a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_not_used.stderr
@@ -0,0 +1,14 @@
+error: at least one trait must be specified
+  --> $DIR/generic_not_used.rs:5:33
+   |
+LL | type WrongGeneric<T: 'static> = impl 'static;
+   |                                 ^^^^^^^^^^^^
+
+error: type parameter `V` is part of concrete type but not used in parameter list for the `impl Trait` type alias
+  --> $DIR/generic_not_used.rs:9:5
+   |
+LL |     v
+   |     ^
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.rs b/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.rs
new file mode 100644
index 000000000..cb9077647
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.rs
@@ -0,0 +1,16 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {
+    let y = 42;
+    let x = wrong_generic(&y);
+    let z: i32 = x;
+    //~^ ERROR non-defining opaque type use
+}
+
+type WrongGeneric<T> = impl 'static;
+//~^ ERROR: at least one trait must be specified
+
+fn wrong_generic<T>(t: T) -> WrongGeneric<T> {
+    t
+    //~^ ERROR the parameter type `T` may not live long enough
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.stderr b/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.stderr
new file mode 100644
index 000000000..ba583241a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.stderr
@@ -0,0 +1,32 @@
+error: at least one trait must be specified
+  --> $DIR/generic_type_does_not_live_long_enough.rs:10:24
+   |
+LL | type WrongGeneric<T> = impl 'static;
+   |                        ^^^^^^^^^^^^
+
+error: non-defining opaque type use in defining scope
+  --> $DIR/generic_type_does_not_live_long_enough.rs:6:18
+   |
+LL |     let z: i32 = x;
+   |                  ^
+   |
+note: used non-generic type `&'static i32` for generic parameter
+  --> $DIR/generic_type_does_not_live_long_enough.rs:10:19
+   |
+LL | type WrongGeneric<T> = impl 'static;
+   |                   ^
+
+error[E0310]: the parameter type `T` may not live long enough
+  --> $DIR/generic_type_does_not_live_long_enough.rs:14:5
+   |
+LL |     t
+   |     ^ ...so that the type `T` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound...
+   |
+LL | fn wrong_generic<T: 'static>(t: T) -> WrongGeneric<T> {
+   |                   +++++++++
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0310`.
diff --git a/src/test/ui/type-alias-impl-trait/generic_underconstrained.rs b/src/test/ui/type-alias-impl-trait/generic_underconstrained.rs
new file mode 100644
index 000000000..d87a25aad
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_underconstrained.rs
@@ -0,0 +1,12 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+trait Trait {}
+type Underconstrained<T: Trait> = impl Send;
+
+// no `Trait` bound
+fn underconstrain<T>(_: T) -> Underconstrained<T> {
+    //~^ ERROR the trait bound `T: Trait`
+    unimplemented!()
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_underconstrained.stderr b/src/test/ui/type-alias-impl-trait/generic_underconstrained.stderr
new file mode 100644
index 000000000..c73288329
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_underconstrained.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the trait bound `T: Trait` is not satisfied
+  --> $DIR/generic_underconstrained.rs:9:31
+   |
+LL | fn underconstrain<T>(_: T) -> Underconstrained<T> {
+   |                               ^^^^^^^^^^^^^^^^^^^ the trait `Trait` is not implemented for `T`
+   |
+note: required by a bound in `Underconstrained`
+  --> $DIR/generic_underconstrained.rs:6:26
+   |
+LL | type Underconstrained<T: Trait> = impl Send;
+   |                          ^^^^^ required by this bound in `Underconstrained`
+help: consider restricting type parameter `T`
+   |
+LL | fn underconstrain<T: Trait>(_: T) -> Underconstrained<T> {
+   |                    +++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/generic_underconstrained2.rs b/src/test/ui/type-alias-impl-trait/generic_underconstrained2.rs
new file mode 100644
index 000000000..8adc0bf32
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_underconstrained2.rs
@@ -0,0 +1,19 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+type Underconstrained<T: std::fmt::Debug> = impl Send;
+
+// not a defining use, because it doesn't define *all* possible generics
+fn underconstrained<U>(_: U) -> Underconstrained<U> {
+    //~^ ERROR `U` doesn't implement `Debug`
+    5u32
+}
+
+type Underconstrained2<T: std::fmt::Debug> = impl Send;
+
+// not a defining use, because it doesn't define *all* possible generics
+fn underconstrained2<U, V>(_: U, _: V) -> Underconstrained2<V> {
+    //~^ ERROR `V` doesn't implement `Debug`
+    5u32
+}
diff --git a/src/test/ui/type-alias-impl-trait/generic_underconstrained2.stderr b/src/test/ui/type-alias-impl-trait/generic_underconstrained2.stderr
new file mode 100644
index 000000000..d77d978aa
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_underconstrained2.stderr
@@ -0,0 +1,35 @@
+error[E0277]: `U` doesn't implement `Debug`
+  --> $DIR/generic_underconstrained2.rs:8:33
+   |
+LL | fn underconstrained<U>(_: U) -> Underconstrained<U> {
+   |                                 ^^^^^^^^^^^^^^^^^^^ `U` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+note: required by a bound in `Underconstrained`
+  --> $DIR/generic_underconstrained2.rs:5:26
+   |
+LL | type Underconstrained<T: std::fmt::Debug> = impl Send;
+   |                          ^^^^^^^^^^^^^^^ required by this bound in `Underconstrained`
+help: consider restricting type parameter `U`
+   |
+LL | fn underconstrained<U: std::fmt::Debug>(_: U) -> Underconstrained<U> {
+   |                      +++++++++++++++++
+
+error[E0277]: `V` doesn't implement `Debug`
+  --> $DIR/generic_underconstrained2.rs:16:43
+   |
+LL | fn underconstrained2<U, V>(_: U, _: V) -> Underconstrained2<V> {
+   |                                           ^^^^^^^^^^^^^^^^^^^^ `V` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+note: required by a bound in `Underconstrained2`
+  --> $DIR/generic_underconstrained2.rs:13:27
+   |
+LL | type Underconstrained2<T: std::fmt::Debug> = impl Send;
+   |                           ^^^^^^^^^^^^^^^ required by this bound in `Underconstrained2`
+help: consider restricting type parameter `V`
+   |
+LL | fn underconstrained2<U, V: std::fmt::Debug>(_: U, _: V) -> Underconstrained2<V> {
+   |                          +++++++++++++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs b/src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs
new file mode 100644
index 000000000..851c2f66c
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs
@@ -0,0 +1,17 @@
+// Ensure that we don't ICE if associated type impl trait is used in an impl
+// with an unconstrained type parameter.
+
+#![feature(type_alias_impl_trait)]
+
+trait X {
+    type I;
+    fn f() -> Self::I;
+}
+
+impl<T> X for () {
+    //~^ ERROR the type parameter `T` is not constrained
+    type I = impl Sized;
+    fn f() -> Self::I {}
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.stderr b/src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.stderr
new file mode 100644
index 000000000..8cf8fb1d1
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.stderr
@@ -0,0 +1,9 @@
+error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/impl-with-unconstrained-param.rs:11:6
+   |
+LL | impl<T> X for () {
+   |      ^ unconstrained type parameter
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0207`.
diff --git a/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.rs b/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.rs
new file mode 100644
index 000000000..685d76ee3
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.rs
@@ -0,0 +1,15 @@
+// Regression test for issue 67856
+
+#![feature(unboxed_closures)]
+#![feature(type_alias_impl_trait)]
+#![feature(fn_traits)]
+
+trait MyTrait {}
+impl MyTrait for () {}
+
+impl<F> FnOnce<()> for &F {
+    //~^ ERROR type parameter `F` must be used
+    type Output = impl MyTrait;
+    extern "rust-call" fn call_once(self, _: ()) -> Self::Output {}
+}
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.stderr b/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.stderr
new file mode 100644
index 000000000..b93ea955c
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.stderr
@@ -0,0 +1,12 @@
+error[E0210]: type parameter `F` must be used as the type parameter for some local type (e.g., `MyStruct<F>`)
+  --> $DIR/incoherent-assoc-imp-trait.rs:10:6
+   |
+LL | impl<F> FnOnce<()> for &F {
+   |      ^ type parameter `F` must be used as the type parameter for some local type
+   |
+   = note: implementing a foreign trait is only possible if at least one of the types for which it is implemented is local
+   = note: only traits defined in the current crate can be implemented for a type parameter
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0210`.
diff --git a/src/test/ui/type-alias-impl-trait/incomplete-inference.rs b/src/test/ui/type-alias-impl-trait/incomplete-inference.rs
new file mode 100644
index 000000000..4c8bf2cfc
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/incomplete-inference.rs
@@ -0,0 +1,14 @@
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl Sized;
+
+fn bar() -> Foo {
+    None
+    //~^ ERROR: type annotations needed [E0282]
+}
+
+fn baz() -> Foo {
+    Some(())
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/incomplete-inference.stderr b/src/test/ui/type-alias-impl-trait/incomplete-inference.stderr
new file mode 100644
index 000000000..9a0e71b4e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/incomplete-inference.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed
+  --> $DIR/incomplete-inference.rs:6:5
+   |
+LL |     None
+   |     ^^^^ cannot infer type of the type parameter `T` declared on the enum `Option`
+   |
+help: consider specifying the generic argument
+   |
+LL |     None::<T>
+   |         +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type-alias-impl-trait/inference-cycle.rs b/src/test/ui/type-alias-impl-trait/inference-cycle.rs
new file mode 100644
index 000000000..79caddf79
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/inference-cycle.rs
@@ -0,0 +1,25 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+mod m {
+    type Foo = impl std::fmt::Debug;
+    //~^ ERROR cycle detected
+
+    // Cycle: error today, but it'd be nice if it eventually worked
+
+    pub fn foo() -> Foo {
+        is_send(bar())
+    }
+
+    pub fn bar() {
+        is_send(foo()); // Today: error
+    }
+
+    fn baz() {
+        let f: Foo = 22_u32;
+    }
+
+    fn is_send<T: Send>(_: T) {}
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/inference-cycle.stderr b/src/test/ui/type-alias-impl-trait/inference-cycle.stderr
new file mode 100644
index 000000000..b9d646b92
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/inference-cycle.stderr
@@ -0,0 +1,22 @@
+error[E0391]: cycle detected when computing type of `m::Foo::{opaque#0}`
+  --> $DIR/inference-cycle.rs:5:16
+   |
+LL |     type Foo = impl std::fmt::Debug;
+   |                ^^^^^^^^^^^^^^^^^^^^
+   |
+note: ...which requires type-checking `m::bar`...
+  --> $DIR/inference-cycle.rs:15:9
+   |
+LL |         is_send(foo()); // Today: error
+   |         ^^^^^^^
+   = note: ...which requires evaluating trait selection obligation `m::Foo: core::marker::Send`...
+   = note: ...which again requires computing type of `m::Foo::{opaque#0}`, completing the cycle
+note: cycle used when checking item types in module `m`
+  --> $DIR/inference-cycle.rs:4:1
+   |
+LL | mod m {
+   | ^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0391`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-52843-closure-constrain.rs b/src/test/ui/type-alias-impl-trait/issue-52843-closure-constrain.rs
new file mode 100644
index 000000000..50eeff0b1
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-52843-closure-constrain.rs
@@ -0,0 +1,13 @@
+// Checks to ensure that we properly detect when a closure constrains an opaque type
+
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {
+    type Opaque = impl Debug;
+    fn _unused() -> Opaque { String::new() }
+    let null = || -> Opaque { 0 };
+    //~^ ERROR: concrete type differs from previous defining opaque type use
+    println!("{:?}", null());
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-52843-closure-constrain.stderr b/src/test/ui/type-alias-impl-trait/issue-52843-closure-constrain.stderr
new file mode 100644
index 000000000..4c5fd2255
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-52843-closure-constrain.stderr
@@ -0,0 +1,14 @@
+error: concrete type differs from previous defining opaque type use
+  --> $DIR/issue-52843-closure-constrain.rs:10:31
+   |
+LL |     let null = || -> Opaque { 0 };
+   |                               ^ expected `String`, got `i32`
+   |
+note: previous use here
+  --> $DIR/issue-52843-closure-constrain.rs:9:30
+   |
+LL |     fn _unused() -> Opaque { String::new() }
+   |                              ^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-52843.rs b/src/test/ui/type-alias-impl-trait/issue-52843.rs
new file mode 100644
index 000000000..159d3ccd2
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-52843.rs
@@ -0,0 +1,15 @@
+#![feature(type_alias_impl_trait)]
+
+type Foo<T> = impl Default;
+
+#[allow(unused)]
+fn foo<T: Default>(t: T) -> Foo<T> {
+    t
+    //~^ ERROR: the trait bound `T: Default` is not satisfied
+}
+
+struct NotDefault;
+
+fn main() {
+    let _ = Foo::<NotDefault>::default();
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-52843.stderr b/src/test/ui/type-alias-impl-trait/issue-52843.stderr
new file mode 100644
index 000000000..acd40f980
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-52843.stderr
@@ -0,0 +1,14 @@
+error[E0277]: the trait bound `T: Default` is not satisfied
+  --> $DIR/issue-52843.rs:7:5
+   |
+LL |     t
+   |     ^ the trait `Default` is not implemented for `T`
+   |
+help: consider restricting type parameter `T`
+   |
+LL | type Foo<T: std::default::Default> = impl Default;
+   |           +++++++++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-53092-2.rs b/src/test/ui/type-alias-impl-trait/issue-53092-2.rs
new file mode 100644
index 000000000..438ac35fd
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53092-2.rs
@@ -0,0 +1,15 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+type Bug<T, U> = impl Fn(T) -> U + Copy; //~ ERROR cycle detected
+
+const CONST_BUG: Bug<u8, ()> = unsafe { std::mem::transmute(|_: u8| ()) };
+//~^ ERROR: cannot transmute
+
+fn make_bug<T, U: From<T>>() -> Bug<T, U> {
+    |x| x.into() //~ ERROR the trait bound `U: From<T>` is not satisfied
+}
+
+fn main() {
+    CONST_BUG(0);
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-53092-2.stderr b/src/test/ui/type-alias-impl-trait/issue-53092-2.stderr
new file mode 100644
index 000000000..1b89d5571
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53092-2.stderr
@@ -0,0 +1,55 @@
+error[E0391]: cycle detected when computing type of `Bug::{opaque#0}`
+  --> $DIR/issue-53092-2.rs:4:18
+   |
+LL | type Bug<T, U> = impl Fn(T) -> U + Copy;
+   |                  ^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: ...which requires type-checking `CONST_BUG`...
+  --> $DIR/issue-53092-2.rs:6:1
+   |
+LL | const CONST_BUG: Bug<u8, ()> = unsafe { std::mem::transmute(|_: u8| ()) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: ...which requires computing layout of `Bug<u8, ()>`...
+   = note: ...which requires normalizing `Bug<u8, ()>`...
+   = note: ...which again requires computing type of `Bug::{opaque#0}`, completing the cycle
+note: cycle used when checking item types in top-level module
+  --> $DIR/issue-53092-2.rs:1:1
+   |
+LL | / #![feature(type_alias_impl_trait)]
+LL | | #![allow(dead_code)]
+LL | |
+LL | | type Bug<T, U> = impl Fn(T) -> U + Copy;
+...  |
+LL | |     CONST_BUG(0);
+LL | | }
+   | |_^
+
+error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
+  --> $DIR/issue-53092-2.rs:6:41
+   |
+LL | const CONST_BUG: Bug<u8, ()> = unsafe { std::mem::transmute(|_: u8| ()) };
+   |                                         ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: source type: `[closure@$DIR/issue-53092-2.rs:6:61: 6:68]` (0 bits)
+   = note: target type: `Bug<u8, ()>` (size can vary because of [type error])
+
+error[E0277]: the trait bound `U: From<T>` is not satisfied
+  --> $DIR/issue-53092-2.rs:10:5
+   |
+LL |     |x| x.into()
+   |     ^^^^^^^^^^^^ the trait `From<T>` is not implemented for `U`
+   |
+note: required by a bound in `make_bug`
+  --> $DIR/issue-53092-2.rs:9:19
+   |
+LL | fn make_bug<T, U: From<T>>() -> Bug<T, U> {
+   |                   ^^^^^^^ required by this bound in `make_bug`
+help: consider restricting type parameter `U`
+   |
+LL | type Bug<T, U: std::convert::From<T>> = impl Fn(T) -> U + Copy;
+   |              +++++++++++++++++++++++
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0277, E0391, E0512.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-53092.rs b/src/test/ui/type-alias-impl-trait/issue-53092.rs
new file mode 100644
index 000000000..1be5b46d6
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53092.rs
@@ -0,0 +1,19 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+type Bug<T, U> = impl Fn(T) -> U + Copy;
+
+union Moo {
+    x: Bug<u8, ()>,
+    y: (),
+}
+
+const CONST_BUG: Bug<u8, ()> = unsafe { Moo { y: () }.x };
+
+fn make_bug<T, U: From<T>>() -> Bug<T, U> {
+    |x| x.into() //~ ERROR the trait bound `U: From<T>` is not satisfied
+}
+
+fn main() {
+    CONST_BUG(0);
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-53092.stderr b/src/test/ui/type-alias-impl-trait/issue-53092.stderr
new file mode 100644
index 000000000..2109cf8a7
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53092.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the trait bound `U: From<T>` is not satisfied
+  --> $DIR/issue-53092.rs:14:5
+   |
+LL |     |x| x.into()
+   |     ^^^^^^^^^^^^ the trait `From<T>` is not implemented for `U`
+   |
+note: required by a bound in `make_bug`
+  --> $DIR/issue-53092.rs:13:19
+   |
+LL | fn make_bug<T, U: From<T>>() -> Bug<T, U> {
+   |                   ^^^^^^^ required by this bound in `make_bug`
+help: consider restricting type parameter `U`
+   |
+LL | type Bug<T, U: std::convert::From<T>> = impl Fn(T) -> U + Copy;
+   |              +++++++++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-53096.rs b/src/test/ui/type-alias-impl-trait/issue-53096.rs
new file mode 100644
index 000000000..007dcf3bc
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53096.rs
@@ -0,0 +1,11 @@
+#![feature(rustc_attrs)]
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl Fn() -> usize;
+const fn bar() -> Foo {
+    || 0usize
+}
+const BAZR: Foo = bar();
+
+#[rustc_error]
+fn main() {} //~ ERROR
diff --git a/src/test/ui/type-alias-impl-trait/issue-53096.stderr b/src/test/ui/type-alias-impl-trait/issue-53096.stderr
new file mode 100644
index 000000000..0af3a75f8
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53096.stderr
@@ -0,0 +1,8 @@
+error: fatal error triggered by #[rustc_error]
+  --> $DIR/issue-53096.rs:11:1
+   |
+LL | fn main() {}
+   | ^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-53398-cyclic-types.rs b/src/test/ui/type-alias-impl-trait/issue-53398-cyclic-types.rs
new file mode 100644
index 000000000..4a11bb502
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53398-cyclic-types.rs
@@ -0,0 +1,10 @@
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl Fn() -> Foo;
+
+fn foo() -> Foo {
+//~^ ERROR: overflow evaluating the requirement
+    foo
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-53398-cyclic-types.stderr b/src/test/ui/type-alias-impl-trait/issue-53398-cyclic-types.stderr
new file mode 100644
index 000000000..d20b1cc6d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53398-cyclic-types.stderr
@@ -0,0 +1,11 @@
+error[E0275]: overflow evaluating the requirement `fn() -> Foo {foo}: Sized`
+  --> $DIR/issue-53398-cyclic-types.rs:5:13
+   |
+LL | fn foo() -> Foo {
+   |             ^^^
+   |
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_53398_cyclic_types`)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0275`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-53598.rs b/src/test/ui/type-alias-impl-trait/issue-53598.rs
new file mode 100644
index 000000000..9c1cbf926
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53598.rs
@@ -0,0 +1,27 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+pub trait Foo {
+    type Item: Debug;
+
+    fn foo<T: Debug>(_: T) -> Self::Item;
+}
+
+#[derive(Debug)]
+pub struct S<T>(std::marker::PhantomData<T>);
+
+pub struct S2;
+
+impl Foo for S2 {
+    type Item = impl Debug;
+
+    fn foo<T: Debug>(_: T) -> Self::Item {
+        S::<T>(Default::default())
+        //~^ Error type parameter `T` is part of concrete type but not used in parameter list for the `impl Trait` type alias
+    }
+}
+
+fn main() {
+    S2::foo(123);
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-53598.stderr b/src/test/ui/type-alias-impl-trait/issue-53598.stderr
new file mode 100644
index 000000000..f8b8201e2
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53598.stderr
@@ -0,0 +1,8 @@
+error: type parameter `T` is part of concrete type but not used in parameter list for the `impl Trait` type alias
+  --> $DIR/issue-53598.rs:20:9
+   |
+LL |         S::<T>(Default::default())
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-53678-generator-and-const-fn.rs b/src/test/ui/type-alias-impl-trait/issue-53678-generator-and-const-fn.rs
new file mode 100644
index 000000000..a3f126d56
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53678-generator-and-const-fn.rs
@@ -0,0 +1,19 @@
+#![feature(generators, generator_trait, rustc_attrs)]
+#![feature(type_alias_impl_trait)]
+
+use std::ops::Generator;
+
+type GenOnce<Y, R> = impl Generator<Yield = Y, Return = R>;
+
+const fn const_generator<Y, R>(yielding: Y, returning: R) -> GenOnce<Y, R> {
+    move || {
+        yield yielding;
+
+        return returning;
+    }
+}
+
+const FOO: GenOnce<usize, usize> = const_generator(10, 100);
+
+#[rustc_error]
+fn main() {} //~ ERROR
diff --git a/src/test/ui/type-alias-impl-trait/issue-53678-generator-and-const-fn.stderr b/src/test/ui/type-alias-impl-trait/issue-53678-generator-and-const-fn.stderr
new file mode 100644
index 000000000..eb1c9603a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-53678-generator-and-const-fn.stderr
@@ -0,0 +1,8 @@
+error: fatal error triggered by #[rustc_error]
+  --> $DIR/issue-53678-generator-and-const-fn.rs:19:1
+   |
+LL | fn main() {}
+   | ^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-55099-lifetime-inference.rs b/src/test/ui/type-alias-impl-trait/issue-55099-lifetime-inference.rs
new file mode 100644
index 000000000..af0780ab0
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-55099-lifetime-inference.rs
@@ -0,0 +1,26 @@
+// check-pass
+// Regression test for issue #55099
+// Tests that we don't incorrectly consider a lifetime to part
+// of the concrete type
+
+#![feature(type_alias_impl_trait)]
+
+trait Future {}
+
+struct AndThen<F>(F);
+
+impl<F> Future for AndThen<F> {}
+
+struct Foo<'a> {
+    x: &'a mut (),
+}
+
+type F = impl Future;
+
+impl<'a> Foo<'a> {
+    fn reply(&mut self) -> F {
+        AndThen(|| ())
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-57188-associate-impl-capture.rs b/src/test/ui/type-alias-impl-trait/issue-57188-associate-impl-capture.rs
new file mode 100644
index 000000000..3a7a5da07
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-57188-associate-impl-capture.rs
@@ -0,0 +1,24 @@
+// Regression test for #57188
+
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+struct Baz<'a> {
+    source: &'a str,
+}
+
+trait Foo<'a> {
+    type T: Iterator<Item = Baz<'a>> + 'a;
+    fn foo(source: &'a str) -> Self::T;
+}
+
+struct Bar;
+impl<'a> Foo<'a> for Bar {
+    type T = impl Iterator<Item = Baz<'a>> + 'a;
+    fn foo(source: &'a str) -> Self::T {
+        std::iter::once(Baz { source })
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-57611-trait-alias.rs b/src/test/ui/type-alias-impl-trait/issue-57611-trait-alias.rs
new file mode 100644
index 000000000..067ed7ea1
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-57611-trait-alias.rs
@@ -0,0 +1,27 @@
+// Regression test for issue #57611
+// Ensures that we don't ICE
+// FIXME: This should compile, but it currently doesn't
+// known-bug: unknown
+
+#![feature(trait_alias)]
+#![feature(type_alias_impl_trait)]
+
+trait Foo {
+    type Bar: Baz<Self, Self>;
+
+    fn bar(&self) -> Self::Bar;
+}
+
+struct X;
+
+impl Foo for X {
+    type Bar = impl Baz<Self, Self>;
+
+    fn bar(&self) -> Self::Bar {
+        |x| x
+    }
+}
+
+trait Baz<A: ?Sized, B: ?Sized> = Fn(&A) -> &B;
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-57611-trait-alias.stderr b/src/test/ui/type-alias-impl-trait/issue-57611-trait-alias.stderr
new file mode 100644
index 000000000..f14bf6b0f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-57611-trait-alias.stderr
@@ -0,0 +1,26 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-57611-trait-alias.rs:21:9
+   |
+LL |         |x| x
+   |         ^^^^^ one type is more general than the other
+   |
+   = note: expected trait `for<'r> Fn<(&'r X,)>`
+              found trait `Fn<(&X,)>`
+note: this closure does not fulfill the lifetime requirements
+  --> $DIR/issue-57611-trait-alias.rs:21:9
+   |
+LL |         |x| x
+   |         ^^^
+
+error: implementation of `FnOnce` is not general enough
+  --> $DIR/issue-57611-trait-alias.rs:21:9
+   |
+LL |         |x| x
+   |         ^^^^^ implementation of `FnOnce` is not general enough
+   |
+   = note: closure with signature `fn(&'2 X) -> &X` must implement `FnOnce<(&'1 X,)>`, for any lifetime `'1`...
+   = note: ...but it actually implements `FnOnce<(&'2 X,)>`, for some specific lifetime `'2`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-57700.rs b/src/test/ui/type-alias-impl-trait/issue-57700.rs
new file mode 100644
index 000000000..484589387
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-57700.rs
@@ -0,0 +1,21 @@
+#![feature(arbitrary_self_types)]
+#![feature(type_alias_impl_trait)]
+
+use std::ops::Deref;
+
+trait Foo {
+    type Bar: Foo;
+
+    fn foo(self: impl Deref<Target = Self>) -> Self::Bar;
+}
+
+impl<C> Foo for C {
+    type Bar = impl Foo;
+
+    fn foo(self: impl Deref<Target = Self>) -> Self::Bar {
+        self
+        //~^ Error type parameter `impl Deref<Target = Self>` is part of concrete type but not used in parameter list for the `impl Trait` type alias
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-57700.stderr b/src/test/ui/type-alias-impl-trait/issue-57700.stderr
new file mode 100644
index 000000000..31b6df5d4
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-57700.stderr
@@ -0,0 +1,8 @@
+error: type parameter `impl Deref<Target = Self>` is part of concrete type but not used in parameter list for the `impl Trait` type alias
+  --> $DIR/issue-57700.rs:16:9
+   |
+LL |         self
+   |         ^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-57807-associated-type.rs b/src/test/ui/type-alias-impl-trait/issue-57807-associated-type.rs
new file mode 100644
index 000000000..fcab2c7db
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-57807-associated-type.rs
@@ -0,0 +1,31 @@
+// Regression test for issue #57807 - ensure
+// that we properly unify associated types within
+// a type alias impl trait
+// check-pass
+#![feature(type_alias_impl_trait)]
+
+trait Bar {
+    type A;
+}
+
+impl Bar for () {
+    type A = ();
+}
+
+trait Foo {
+    type A;
+    type B: Bar<A = Self::A>;
+
+    fn foo() -> Self::B;
+}
+
+impl Foo for () {
+    type A = ();
+    type B = impl Bar<A = Self::A>;
+
+    fn foo() -> Self::B {
+        ()
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-57961.rs b/src/test/ui/type-alias-impl-trait/issue-57961.rs
new file mode 100644
index 000000000..472886c9c
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-57961.rs
@@ -0,0 +1,18 @@
+#![feature(type_alias_impl_trait)]
+
+type X = impl Sized;
+
+trait Foo {
+    type Bar: Iterator<Item = X>;
+}
+
+impl Foo for () {
+    type Bar = std::vec::IntoIter<u32>;
+    //~^ ERROR type mismatch resolving `<std::vec::IntoIter<u32> as Iterator>::Item == X
+}
+
+fn incoherent() {
+    let f: X = 22_i32;
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-57961.stderr b/src/test/ui/type-alias-impl-trait/issue-57961.stderr
new file mode 100644
index 000000000..ed4caf6ce
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-57961.stderr
@@ -0,0 +1,20 @@
+error[E0271]: type mismatch resolving `<std::vec::IntoIter<u32> as Iterator>::Item == X`
+  --> $DIR/issue-57961.rs:10:16
+   |
+LL | type X = impl Sized;
+   |          ---------- the expected opaque type
+...
+LL |     type Bar = std::vec::IntoIter<u32>;
+   |                ^^^^^^^^^^^^^^^^^^^^^^^ expected opaque type, found `u32`
+   |
+   = note: expected opaque type `X`
+                     found type `u32`
+note: required by a bound in `Foo::Bar`
+  --> $DIR/issue-57961.rs:6:24
+   |
+LL |     type Bar: Iterator<Item = X>;
+   |                        ^^^^^^^^ required by this bound in `Foo::Bar`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-58662-generator-with-lifetime.rs b/src/test/ui/type-alias-impl-trait/issue-58662-generator-with-lifetime.rs
new file mode 100644
index 000000000..f20ddf020
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-58662-generator-with-lifetime.rs
@@ -0,0 +1,39 @@
+// check-pass
+
+#![feature(generators, generator_trait)]
+#![feature(type_alias_impl_trait)]
+
+use std::ops::{Generator, GeneratorState};
+use std::pin::Pin;
+
+type RandGenerator<'a> = impl Generator<Return = (), Yield = u64> + 'a;
+fn rand_generator<'a>(rng: &'a ()) -> RandGenerator<'a> {
+    move || {
+        let _rng = rng;
+        loop {
+            yield 0;
+        }
+    }
+}
+
+pub type RandGeneratorWithIndirection<'a> = impl Generator<Return = (), Yield = u64> + 'a;
+pub fn rand_generator_with_indirection<'a>(rng: &'a ()) -> RandGeneratorWithIndirection<'a> {
+    fn helper<'b>(rng: &'b ()) -> impl 'b + Generator<Return = (), Yield = u64> {
+        move || {
+            let _rng = rng;
+            loop {
+                yield 0;
+            }
+        }
+    }
+
+    helper(rng)
+}
+
+fn main() {
+    let mut gen = rand_generator(&());
+    match unsafe { Pin::new_unchecked(&mut gen) }.resume(()) {
+        GeneratorState::Yielded(_) => {}
+        GeneratorState::Complete(_) => {}
+    };
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-58887.rs b/src/test/ui/type-alias-impl-trait/issue-58887.rs
new file mode 100644
index 000000000..96ac78602
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-58887.rs
@@ -0,0 +1,22 @@
+// run-pass
+
+#![feature(type_alias_impl_trait)]
+
+trait UnwrapItemsExt {
+    type Iter;
+    fn unwrap_items(self) -> Self::Iter;
+}
+
+impl<I, T, E> UnwrapItemsExt for I
+where
+    I: Iterator<Item = Result<T, E>>,
+    E: std::fmt::Debug,
+{
+    type Iter = impl Iterator<Item = T>;
+
+    fn unwrap_items(self) -> Self::Iter {
+        self.map(|x| x.unwrap())
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-58951-2.rs b/src/test/ui/type-alias-impl-trait/issue-58951-2.rs
new file mode 100644
index 000000000..e4ba7f8e2
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-58951-2.rs
@@ -0,0 +1,18 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+mod defining_use_scope {
+    pub type A = impl Iterator;
+
+    pub fn def_a() -> A {
+        0..1
+    }
+}
+use defining_use_scope::*;
+
+pub fn use_a() {
+    def_a().map(|x| x);
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-58951.rs b/src/test/ui/type-alias-impl-trait/issue-58951.rs
new file mode 100644
index 000000000..7303cbab4
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-58951.rs
@@ -0,0 +1,15 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+type A = impl Iterator;
+
+fn def_a() -> A {
+    0..1
+}
+
+pub fn use_a() {
+    def_a().map(|x| x);
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-60371.rs b/src/test/ui/type-alias-impl-trait/issue-60371.rs
new file mode 100644
index 000000000..9a40f3d9b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-60371.rs
@@ -0,0 +1,14 @@
+trait Bug {
+    type Item: Bug;
+
+    const FUN: fn() -> Self::Item;
+}
+
+impl Bug for &() {
+    type Item = impl Bug; //~ ERROR `impl Trait` in type aliases is unstable
+
+    const FUN: fn() -> Self::Item = || ();
+    //~^ ERROR the trait bound `(): Bug` is not satisfied
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-60371.stderr b/src/test/ui/type-alias-impl-trait/issue-60371.stderr
new file mode 100644
index 000000000..082b0f0c3
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-60371.stderr
@@ -0,0 +1,21 @@
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/issue-60371.rs:8:17
+   |
+LL |     type Item = impl Bug;
+   |                 ^^^^^^^^
+   |
+   = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0277]: the trait bound `(): Bug` is not satisfied
+  --> $DIR/issue-60371.rs:10:40
+   |
+LL |     const FUN: fn() -> Self::Item = || ();
+   |                                        ^ the trait `Bug` is not implemented for `()`
+   |
+   = help: the trait `Bug` is implemented for `&()`
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0277, E0658.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-60407.rs b/src/test/ui/type-alias-impl-trait/issue-60407.rs
new file mode 100644
index 000000000..b833429c7
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-60407.rs
@@ -0,0 +1,15 @@
+#![feature(type_alias_impl_trait, rustc_attrs)]
+
+type Debuggable = impl core::fmt::Debug;
+
+static mut TEST: Option<Debuggable> = None;
+
+#[rustc_error]
+fn main() {
+    //~^ ERROR
+    unsafe { TEST = Some(foo()) }
+}
+
+fn foo() -> Debuggable {
+    0u32
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-60407.stderr b/src/test/ui/type-alias-impl-trait/issue-60407.stderr
new file mode 100644
index 000000000..fecee2779
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-60407.stderr
@@ -0,0 +1,8 @@
+error: fatal error triggered by #[rustc_error]
+  --> $DIR/issue-60407.rs:8:1
+   |
+LL | fn main() {
+   | ^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-60564-working.rs b/src/test/ui/type-alias-impl-trait/issue-60564-working.rs
new file mode 100644
index 000000000..38accc824
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-60564-working.rs
@@ -0,0 +1,24 @@
+#![feature(type_alias_impl_trait)]
+
+// check-pass
+
+trait IterBits {
+    type BitsIter: Iterator<Item = u8>;
+    fn iter_bits(self, n: u8) -> Self::BitsIter;
+}
+
+impl<T: Copy, E> IterBits for T
+where
+    T: std::ops::Shr<Output = T>
+        + std::ops::BitAnd<T, Output = T>
+        + std::convert::From<u8>
+        + std::convert::TryInto<u8, Error = E>,
+    E: std::fmt::Debug,
+{
+    type BitsIter = impl std::iter::Iterator<Item = u8>;
+    fn iter_bits(self, n: u8) -> Self::BitsIter {
+        (0u8..n).rev().map(move |shift| ((self >> T::from(shift)) & T::from(1)).try_into().unwrap())
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-60564.rs b/src/test/ui/type-alias-impl-trait/issue-60564.rs
new file mode 100644
index 000000000..4fc767931
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-60564.rs
@@ -0,0 +1,25 @@
+#![feature(type_alias_impl_trait)]
+
+trait IterBits {
+    type BitsIter: Iterator<Item = u8>;
+    fn iter_bits(self, n: u8) -> Self::BitsIter;
+}
+
+type IterBitsIter<T, E, I> = impl std::iter::Iterator<Item = I>;
+
+impl<T: Copy, E> IterBits for T
+where
+    T: std::ops::Shr<Output = T>
+        + std::ops::BitAnd<T, Output = T>
+        + std::convert::From<u8>
+        + std::convert::TryInto<u8, Error = E>,
+    E: std::fmt::Debug,
+{
+    type BitsIter = IterBitsIter<T, E, u8>;
+    fn iter_bits(self, n: u8) -> Self::BitsIter {
+        (0u8..n).rev().map(move |shift| ((self >> T::from(shift)) & T::from(1)).try_into().unwrap())
+        //~^ ERROR non-defining opaque type use in defining scope
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-60564.stderr b/src/test/ui/type-alias-impl-trait/issue-60564.stderr
new file mode 100644
index 000000000..bbc93657b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-60564.stderr
@@ -0,0 +1,14 @@
+error: non-defining opaque type use in defining scope
+  --> $DIR/issue-60564.rs:20:9
+   |
+LL |         (0u8..n).rev().map(move |shift| ((self >> T::from(shift)) & T::from(1)).try_into().unwrap())
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: used non-generic type `u8` for generic parameter
+  --> $DIR/issue-60564.rs:8:25
+   |
+LL | type IterBitsIter<T, E, I> = impl std::iter::Iterator<Item = I>;
+   |                         ^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-60662.rs b/src/test/ui/type-alias-impl-trait/issue-60662.rs
new file mode 100644
index 000000000..b9faa668b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-60662.rs
@@ -0,0 +1,10 @@
+// check-pass
+// compile-flags: -Z unpretty=hir
+
+#![feature(type_alias_impl_trait)]
+
+trait Animal {}
+
+fn main() {
+    pub type ServeFut = impl Animal;
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-60662.stdout b/src/test/ui/type-alias-impl-trait/issue-60662.stdout
new file mode 100644
index 000000000..5b3d7375d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-60662.stdout
@@ -0,0 +1,14 @@
+// check-pass
+// compile-flags: -Z unpretty=hir
+
+#![feature(type_alias_impl_trait)]
+#[prelude_import]
+use ::std::prelude::rust_2015::*;
+#[macro_use]
+extern crate std;
+
+trait Animal { }
+
+fn main() {
+        type ServeFut = /*impl Trait*/;
+    }
diff --git a/src/test/ui/type-alias-impl-trait/issue-62000-associate-impl-trait-lifetimes.rs b/src/test/ui/type-alias-impl-trait/issue-62000-associate-impl-trait-lifetimes.rs
new file mode 100644
index 000000000..36779a0ce
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-62000-associate-impl-trait-lifetimes.rs
@@ -0,0 +1,38 @@
+// Regression test for #62988
+
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+trait MyTrait {
+    type AssocType: Send;
+    fn ret(&self) -> Self::AssocType;
+}
+
+impl MyTrait for () {
+    type AssocType = impl Send;
+    fn ret(&self) -> Self::AssocType {
+        ()
+    }
+}
+
+impl<'a> MyTrait for &'a () {
+    type AssocType = impl Send;
+    fn ret(&self) -> Self::AssocType {
+        ()
+    }
+}
+
+trait MyLifetimeTrait<'a> {
+    type AssocType: Send + 'a;
+    fn ret(&self) -> Self::AssocType;
+}
+
+impl<'a> MyLifetimeTrait<'a> for &'a () {
+    type AssocType = impl Send + 'a;
+    fn ret(&self) -> Self::AssocType {
+        *self
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-63263-closure-return.rs b/src/test/ui/type-alias-impl-trait/issue-63263-closure-return.rs
new file mode 100644
index 000000000..7414611a7
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-63263-closure-return.rs
@@ -0,0 +1,13 @@
+// Regression test for issue #63263.
+// Tests that we properly handle closures with an explicit return type
+// that return an opaque type.
+
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+pub type Closure = impl FnOnce();
+
+fn main() {
+    || -> Closure { || () };
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-63279.rs b/src/test/ui/type-alias-impl-trait/issue-63279.rs
new file mode 100644
index 000000000..97332e16d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-63279.rs
@@ -0,0 +1,15 @@
+// compile-flags: -Zsave-analysis
+
+#![feature(type_alias_impl_trait)]
+
+type Closure = impl FnOnce();
+
+fn c() -> Closure {
+    //~^ ERROR: expected a `FnOnce<()>` closure, found `()`
+    || -> Closure { || () }
+    //~^ ERROR: mismatched types
+    //~| ERROR: mismatched types
+    //~| ERROR: expected a `FnOnce<()>` closure, found `()`
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-63279.stderr b/src/test/ui/type-alias-impl-trait/issue-63279.stderr
new file mode 100644
index 000000000..110b8d1ee
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-63279.stderr
@@ -0,0 +1,48 @@
+error[E0277]: expected a `FnOnce<()>` closure, found `()`
+  --> $DIR/issue-63279.rs:7:11
+   |
+LL | fn c() -> Closure {
+   |           ^^^^^^^ expected an `FnOnce<()>` closure, found `()`
+   |
+   = help: the trait `FnOnce<()>` is not implemented for `()`
+   = note: wrap the `()` in a closure with no arguments: `|| { /* code */ }`
+
+error[E0277]: expected a `FnOnce<()>` closure, found `()`
+  --> $DIR/issue-63279.rs:9:11
+   |
+LL |     || -> Closure { || () }
+   |           ^^^^^^^ expected an `FnOnce<()>` closure, found `()`
+   |
+   = help: the trait `FnOnce<()>` is not implemented for `()`
+   = note: wrap the `()` in a closure with no arguments: `|| { /* code */ }`
+
+error[E0308]: mismatched types
+  --> $DIR/issue-63279.rs:9:21
+   |
+LL |     || -> Closure { || () }
+   |                     ^^^^^ expected `()`, found closure
+   |
+   = note: expected unit type `()`
+                found closure `[closure@$DIR/issue-63279.rs:9:21: 9:23]`
+help: use parentheses to call this closure
+   |
+LL |     || -> Closure { (|| ())() }
+   |                     +     +++
+
+error[E0308]: mismatched types
+  --> $DIR/issue-63279.rs:9:5
+   |
+LL |     || -> Closure { || () }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found closure
+   |
+   = note: expected unit type `()`
+                found closure `[closure@$DIR/issue-63279.rs:9:5: 9:18]`
+help: use parentheses to call this closure
+   |
+LL |     (|| -> Closure { || () })()
+   |     +                       +++
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0277, E0308.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-63355.rs b/src/test/ui/type-alias-impl-trait/issue-63355.rs
new file mode 100644
index 000000000..7066a0535
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-63355.rs
@@ -0,0 +1,46 @@
+#![feature(type_alias_impl_trait)]
+// check-pass
+
+pub trait Foo {}
+
+pub trait Bar {
+    type Foo: Foo;
+
+    fn foo() -> Self::Foo;
+}
+
+pub trait Baz {
+    type Foo: Foo;
+    type Bar: Bar<Foo = Self::Foo>;
+
+    fn foo() -> Self::Foo;
+    fn bar() -> Self::Bar;
+}
+
+impl Foo for () {}
+
+impl Bar for () {
+    type Foo = FooImpl;
+
+    fn foo() -> Self::Foo {
+        ()
+    }
+}
+
+pub type FooImpl = impl Foo;
+pub type BarImpl = impl Bar<Foo = FooImpl>;
+
+impl Baz for () {
+    type Foo = FooImpl;
+    type Bar = BarImpl;
+
+    fn foo() -> Self::Foo {
+        ()
+    }
+
+    fn bar() -> Self::Bar {
+        ()
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-63677-type-alias-coherence.rs b/src/test/ui/type-alias-impl-trait/issue-63677-type-alias-coherence.rs
new file mode 100644
index 000000000..28f4a85c9
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-63677-type-alias-coherence.rs
@@ -0,0 +1,21 @@
+// check-pass
+// Regression test for issue #63677 - ensure that
+// coherence checking can properly handle 'impl trait'
+// in type aliases
+#![feature(type_alias_impl_trait)]
+
+pub trait Trait {}
+pub struct S1<T>(T);
+pub struct S2<T>(T);
+
+pub type T1 = impl Trait;
+pub type T2 = S1<T1>;
+pub type T3 = S2<T2>;
+
+impl<T> Trait for S1<T> {}
+impl<T: Trait> S2<T> {}
+impl T3 {}
+
+pub fn use_t1() -> T1 { S1(()) }
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-65384.rs b/src/test/ui/type-alias-impl-trait/issue-65384.rs
new file mode 100644
index 000000000..9a119c4d2
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-65384.rs
@@ -0,0 +1,15 @@
+#![feature(type_alias_impl_trait)]
+#![allow(incomplete_features)]
+
+trait MyTrait {}
+
+impl MyTrait for () {}
+
+type Bar = impl MyTrait;
+
+impl MyTrait for Bar {}
+//~^ ERROR: cannot implement trait on type alias impl trait
+
+fn bazr() -> Bar { }
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-65384.stderr b/src/test/ui/type-alias-impl-trait/issue-65384.stderr
new file mode 100644
index 000000000..41bcea27e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-65384.stderr
@@ -0,0 +1,14 @@
+error: cannot implement trait on type alias impl trait
+  --> $DIR/issue-65384.rs:10:18
+   |
+LL | impl MyTrait for Bar {}
+   |                  ^^^
+   |
+note: type alias impl trait defined here
+  --> $DIR/issue-65384.rs:8:12
+   |
+LL | type Bar = impl MyTrait;
+   |            ^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-65679-inst-opaque-ty-from-val-twice.rs b/src/test/ui/type-alias-impl-trait/issue-65679-inst-opaque-ty-from-val-twice.rs
new file mode 100644
index 000000000..72c22827f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-65679-inst-opaque-ty-from-val-twice.rs
@@ -0,0 +1,18 @@
+// compile-flags: -Zsave-analysis
+// check-pass
+
+#![feature(type_alias_impl_trait, rustc_attrs)]
+
+type T = impl Sized;
+// The concrete type referred by impl-trait-type-alias(`T`) is guaranteed
+// to be the same as where it occurs, whereas `impl Trait`'s instance is location sensitive;
+// so difference assertion should not be declared on impl-trait-type-alias's instances.
+// for details, check RFC-2515:
+// https://github.com/rust-lang/rfcs/blob/master/text/2515-type_alias_impl_trait.md
+
+fn take(_: fn() -> T) {}
+
+fn main() {
+    take(|| {});
+    take(|| {});
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-65918.rs b/src/test/ui/type-alias-impl-trait/issue-65918.rs
new file mode 100644
index 000000000..af6d50109
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-65918.rs
@@ -0,0 +1,51 @@
+// ignore-test: This now ICEs again.
+
+// build-pass
+
+#![feature(type_alias_impl_trait)]
+
+use std::marker::PhantomData;
+
+/* copied Index and TryFrom for convenience (and simplicity) */
+trait MyIndex<T> {
+    type O;
+    fn my_index(self) -> Self::O;
+}
+trait MyFrom<T>: Sized {
+    type Error;
+    fn my_from(value: T) -> Result<Self, Self::Error>;
+}
+
+/* MCVE starts here */
+trait F {}
+impl F for () {}
+type DummyT<T> = impl F;
+fn _dummy_t<T>() -> DummyT<T> {}
+
+struct Phantom1<T>(PhantomData<T>);
+struct Phantom2<T>(PhantomData<T>);
+struct Scope<T>(Phantom2<DummyT<T>>);
+
+impl<T> Scope<T> {
+    fn new() -> Self {
+        unimplemented!()
+    }
+}
+
+impl<T> MyFrom<Phantom2<T>> for Phantom1<T> {
+    type Error = ();
+    fn my_from(_: Phantom2<T>) -> Result<Self, Self::Error> {
+        unimplemented!()
+    }
+}
+
+impl<T: MyFrom<Phantom2<DummyT<U>>>, U> MyIndex<Phantom1<T>> for Scope<U> {
+    type O = T;
+    fn my_index(self) -> Self::O {
+        MyFrom::my_from(self.0).ok().unwrap()
+    }
+}
+
+fn main() {
+    let _pos: Phantom1<DummyT<()>> = Scope::new().my_index();
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-66580-closure-coherence.rs b/src/test/ui/type-alias-impl-trait/issue-66580-closure-coherence.rs
new file mode 100644
index 000000000..d97270c31
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-66580-closure-coherence.rs
@@ -0,0 +1,21 @@
+// Regression test for issue #66580
+// Ensures that we don't try to determine whether a closure
+// is foreign when it's the underlying type of an opaque type
+// check-pass
+#![feature(type_alias_impl_trait)]
+
+type Closure = impl FnOnce();
+
+fn closure() -> Closure {
+    || {}
+}
+
+struct Wrap<T> {
+    f: T,
+}
+
+impl Wrap<Closure> {}
+
+impl<T> Wrap<T> {}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-67844-nested-opaque.rs b/src/test/ui/type-alias-impl-trait/issue-67844-nested-opaque.rs
new file mode 100644
index 000000000..cd219328a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-67844-nested-opaque.rs
@@ -0,0 +1,33 @@
+// check-pass
+// Regression test for issue #67844
+// Ensures that we properly handle nested TAIT occurrences
+// with generic parameters
+
+#![feature(type_alias_impl_trait)]
+
+trait WithAssoc {
+    type AssocType;
+}
+
+trait WithParam<A> {}
+
+type Return<A> = impl WithAssoc<AssocType = impl WithParam<A>>;
+
+struct MyParam;
+impl<A> WithParam<A> for MyParam {}
+
+struct MyStruct;
+
+impl WithAssoc for MyStruct {
+    type AssocType = MyParam;
+}
+
+fn my_fun<A>() -> Return<A> {
+    MyStruct
+}
+
+fn my_other_fn<A>() -> impl WithAssoc<AssocType = impl WithParam<A>> {
+    MyStruct
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use-2.rs b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use-2.rs
new file mode 100644
index 000000000..5223fb1c7
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use-2.rs
@@ -0,0 +1,14 @@
+// Regression test for issue #68368
+// Ensures that we don't ICE when emitting an error
+// for a non-defining use when lifetimes are involved
+
+#![feature(type_alias_impl_trait)]
+trait Trait<T> {}
+type Alias<'a, U> = impl Trait<U>;
+
+fn f<'a>() -> Alias<'a, ()> {}
+//~^ ERROR non-defining opaque type use in defining scope
+
+fn main() {}
+
+impl<X> Trait<X> for () {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use-2.stderr b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use-2.stderr
new file mode 100644
index 000000000..7fb9a0c41
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use-2.stderr
@@ -0,0 +1,14 @@
+error: non-defining opaque type use in defining scope
+  --> $DIR/issue-68368-non-defining-use-2.rs:9:29
+   |
+LL | fn f<'a>() -> Alias<'a, ()> {}
+   |                             ^^
+   |
+note: used non-generic type `()` for generic parameter
+  --> $DIR/issue-68368-non-defining-use-2.rs:7:16
+   |
+LL | type Alias<'a, U> = impl Trait<U>;
+   |                ^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.rs b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.rs
new file mode 100644
index 000000000..b50462bf2
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.rs
@@ -0,0 +1,14 @@
+// Regression test for issue #68368
+// Ensures that we don't ICE when emitting an error
+// for a non-defining use when lifetimes are involved
+
+#![feature(type_alias_impl_trait)]
+trait Trait<T> {}
+type Alias<'a, U> = impl Trait<U>;
+
+fn f<'a>() -> Alias<'a, ()> {}
+//~^ ERROR non-defining opaque type use in defining scope
+
+fn main() {}
+
+impl Trait<()> for () {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.stderr b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.stderr
new file mode 100644
index 000000000..8059621b6
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.stderr
@@ -0,0 +1,14 @@
+error: non-defining opaque type use in defining scope
+  --> $DIR/issue-68368-non-defining-use.rs:9:29
+   |
+LL | fn f<'a>() -> Alias<'a, ()> {}
+   |                             ^^
+   |
+note: used non-generic type `()` for generic parameter
+  --> $DIR/issue-68368-non-defining-use.rs:7:16
+   |
+LL | type Alias<'a, U> = impl Trait<U>;
+   |                ^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-69136-inner-lifetime-resolve-error.rs b/src/test/ui/type-alias-impl-trait/issue-69136-inner-lifetime-resolve-error.rs
new file mode 100644
index 000000000..428454bc0
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-69136-inner-lifetime-resolve-error.rs
@@ -0,0 +1,23 @@
+// Regression test for #69136
+
+#![feature(type_alias_impl_trait)]
+
+trait SomeTrait {}
+
+impl SomeTrait for () {}
+
+trait WithAssoc<A> {
+    type AssocType;
+}
+
+impl<T> WithAssoc<T> for () {
+    type AssocType = ();
+}
+
+type Return<A> = impl WithAssoc<A, AssocType = impl SomeTrait + 'a>;
+//~^ ERROR use of undeclared lifetime name `'a`
+
+fn my_fun() -> Return<()> {}
+//~^ ERROR non-defining opaque type use in defining scope
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-69136-inner-lifetime-resolve-error.stderr b/src/test/ui/type-alias-impl-trait/issue-69136-inner-lifetime-resolve-error.stderr
new file mode 100644
index 000000000..7b50c8af2
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-69136-inner-lifetime-resolve-error.stderr
@@ -0,0 +1,31 @@
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/issue-69136-inner-lifetime-resolve-error.rs:17:65
+   |
+LL | type Return<A> = impl WithAssoc<A, AssocType = impl SomeTrait + 'a>;
+   |                                                                 ^^ undeclared lifetime
+   |
+   = note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
+help: consider making the bound lifetime-generic with a new `'a` lifetime
+   |
+LL | type Return<A> = impl for<'a> WithAssoc<A, AssocType = impl SomeTrait + 'a>;
+   |                       +++++++
+help: consider introducing lifetime `'a` here
+   |
+LL | type Return<'a, A> = impl WithAssoc<A, AssocType = impl SomeTrait + 'a>;
+   |             +++
+
+error: non-defining opaque type use in defining scope
+  --> $DIR/issue-69136-inner-lifetime-resolve-error.rs:20:27
+   |
+LL | fn my_fun() -> Return<()> {}
+   |                           ^^
+   |
+note: used non-generic type `()` for generic parameter
+  --> $DIR/issue-69136-inner-lifetime-resolve-error.rs:17:13
+   |
+LL | type Return<A> = impl WithAssoc<A, AssocType = impl SomeTrait + 'a>;
+   |             ^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0261`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-69136-inner-lifetime-resolve-ok.rs b/src/test/ui/type-alias-impl-trait/issue-69136-inner-lifetime-resolve-ok.rs
new file mode 100644
index 000000000..a6916eda8
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-69136-inner-lifetime-resolve-ok.rs
@@ -0,0 +1,23 @@
+// Test-pass variant of #69136
+
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+trait SomeTrait {}
+
+impl SomeTrait for () {}
+
+trait WithAssoc {
+    type AssocType;
+}
+
+impl WithAssoc for () {
+    type AssocType = ();
+}
+
+type Return<'a> = impl WithAssoc<AssocType = impl Sized + 'a>;
+
+fn my_fun<'a>() -> Return<'a> {}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-69323.rs b/src/test/ui/type-alias-impl-trait/issue-69323.rs
new file mode 100644
index 000000000..a9bd6daf2
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-69323.rs
@@ -0,0 +1,16 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+use std::iter::{once, Chain};
+
+fn test1<A: Iterator<Item = &'static str>>(x: A) -> Chain<A, impl Iterator<Item = &'static str>> {
+    x.chain(once(","))
+}
+
+type I<A> = Chain<A, impl Iterator<Item = &'static str>>;
+fn test2<A: Iterator<Item = &'static str>>(x: A) -> I<A> {
+    x.chain(once(","))
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-70121.rs b/src/test/ui/type-alias-impl-trait/issue-70121.rs
new file mode 100644
index 000000000..dff0d89d4
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-70121.rs
@@ -0,0 +1,23 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+pub type Successors<'a> = impl Iterator<Item = &'a ()>;
+
+pub fn f<'a>() -> Successors<'a> {
+    None.into_iter()
+}
+
+pub trait Tr {
+    type Item;
+}
+
+impl<'a> Tr for &'a () {
+    type Item = Successors<'a>;
+}
+
+pub fn kazusa<'a>() -> <&'a () as Tr>::Item {
+    None.into_iter()
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-72793.rs b/src/test/ui/type-alias-impl-trait/issue-72793.rs
new file mode 100644
index 000000000..828c87114
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-72793.rs
@@ -0,0 +1,25 @@
+// check-pass
+// compile-flags: -Zmir-opt-level=3
+
+#![feature(type_alias_impl_trait)]
+
+trait T { type Item; }
+
+type Alias<'a> = impl T<Item = &'a ()>;
+
+struct S;
+impl<'a> T for &'a S {
+    type Item = &'a ();
+}
+
+fn filter_positive<'a>() -> Alias<'a> {
+    &S
+}
+
+fn with_positive(fun: impl Fn(Alias<'_>)) {
+    fun(filter_positive());
+}
+
+fn main() {
+    with_positive(|_| ());
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-74244.rs b/src/test/ui/type-alias-impl-trait/issue-74244.rs
new file mode 100644
index 000000000..bb4104b3d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-74244.rs
@@ -0,0 +1,20 @@
+#![feature(type_alias_impl_trait)]
+
+trait Allocator {
+    type Buffer;
+}
+
+struct DefaultAllocator;
+
+impl<T> Allocator for DefaultAllocator {
+    //~^ ERROR: the type parameter `T` is not constrained
+    type Buffer = ();
+}
+
+type A = impl Fn(<DefaultAllocator as Allocator>::Buffer);
+
+fn foo() -> A {
+    |_| ()
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-74244.stderr b/src/test/ui/type-alias-impl-trait/issue-74244.stderr
new file mode 100644
index 000000000..ff6bacd27
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-74244.stderr
@@ -0,0 +1,9 @@
+error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/issue-74244.rs:9:6
+   |
+LL | impl<T> Allocator for DefaultAllocator {
+   |      ^ unconstrained type parameter
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0207`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-74280.rs b/src/test/ui/type-alias-impl-trait/issue-74280.rs
new file mode 100644
index 000000000..ad641eaa0
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-74280.rs
@@ -0,0 +1,12 @@
+// Regression test for #74280.
+
+#![feature(type_alias_impl_trait)]
+
+type Test = impl Copy;
+
+fn test() -> Test {
+    let y = || -> Test { () };
+    7 //~ ERROR mismatched types
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-74280.stderr b/src/test/ui/type-alias-impl-trait/issue-74280.stderr
new file mode 100644
index 000000000..5ed29e0ac
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-74280.stderr
@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-74280.rs:9:5
+   |
+LL | fn test() -> Test {
+   |              ---- expected `_` because of return type
+LL |     let y = || -> Test { () };
+LL |     7
+   |     ^ expected `()`, found integer
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-74761-2.rs b/src/test/ui/type-alias-impl-trait/issue-74761-2.rs
new file mode 100644
index 000000000..d26ca5c3e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-74761-2.rs
@@ -0,0 +1,15 @@
+#![feature(type_alias_impl_trait)]
+
+pub trait A {
+    type B;
+    fn f(&self) -> Self::B;
+}
+impl<'a, 'b> A for () {
+    //~^ ERROR the lifetime parameter `'a` is not constrained
+    //~| ERROR the lifetime parameter `'b` is not constrained
+    type B = impl core::fmt::Debug;
+
+    fn f(&self) -> Self::B {}
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-74761-2.stderr b/src/test/ui/type-alias-impl-trait/issue-74761-2.stderr
new file mode 100644
index 000000000..f15d0a069
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-74761-2.stderr
@@ -0,0 +1,15 @@
+error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/issue-74761-2.rs:7:6
+   |
+LL | impl<'a, 'b> A for () {
+   |      ^^ unconstrained lifetime parameter
+
+error[E0207]: the lifetime parameter `'b` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/issue-74761-2.rs:7:10
+   |
+LL | impl<'a, 'b> A for () {
+   |          ^^ unconstrained lifetime parameter
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0207`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-74761.rs b/src/test/ui/type-alias-impl-trait/issue-74761.rs
new file mode 100644
index 000000000..d26ca5c3e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-74761.rs
@@ -0,0 +1,15 @@
+#![feature(type_alias_impl_trait)]
+
+pub trait A {
+    type B;
+    fn f(&self) -> Self::B;
+}
+impl<'a, 'b> A for () {
+    //~^ ERROR the lifetime parameter `'a` is not constrained
+    //~| ERROR the lifetime parameter `'b` is not constrained
+    type B = impl core::fmt::Debug;
+
+    fn f(&self) -> Self::B {}
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-74761.stderr b/src/test/ui/type-alias-impl-trait/issue-74761.stderr
new file mode 100644
index 000000000..1d016fe07
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-74761.stderr
@@ -0,0 +1,15 @@
+error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/issue-74761.rs:7:6
+   |
+LL | impl<'a, 'b> A for () {
+   |      ^^ unconstrained lifetime parameter
+
+error[E0207]: the lifetime parameter `'b` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/issue-74761.rs:7:10
+   |
+LL | impl<'a, 'b> A for () {
+   |          ^^ unconstrained lifetime parameter
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0207`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-76202-trait-impl-for-tait.rs b/src/test/ui/type-alias-impl-trait/issue-76202-trait-impl-for-tait.rs
new file mode 100644
index 000000000..fb56cc54d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-76202-trait-impl-for-tait.rs
@@ -0,0 +1,24 @@
+// Regression test for issue #76202
+// Tests that we don't ICE when we have a trait impl on a TAIT.
+
+#![feature(type_alias_impl_trait)]
+
+trait Dummy {}
+impl Dummy for () {}
+
+type F = impl Dummy;
+fn f() -> F {}
+
+trait Test {
+    fn test(self);
+}
+
+impl Test for F {
+    //~^ ERROR cannot implement trait
+    fn test(self) {}
+}
+
+fn main() {
+    let x: F = f();
+    x.test();
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-76202-trait-impl-for-tait.stderr b/src/test/ui/type-alias-impl-trait/issue-76202-trait-impl-for-tait.stderr
new file mode 100644
index 000000000..2d4a6854a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-76202-trait-impl-for-tait.stderr
@@ -0,0 +1,14 @@
+error: cannot implement trait on type alias impl trait
+  --> $DIR/issue-76202-trait-impl-for-tait.rs:16:15
+   |
+LL | impl Test for F {
+   |               ^
+   |
+note: type alias impl trait defined here
+  --> $DIR/issue-76202-trait-impl-for-tait.rs:9:10
+   |
+LL | type F = impl Dummy;
+   |          ^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-77179.rs b/src/test/ui/type-alias-impl-trait/issue-77179.rs
new file mode 100644
index 000000000..8d818d4a3
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-77179.rs
@@ -0,0 +1,14 @@
+// Regression test for #77179.
+
+#![feature(type_alias_impl_trait)]
+
+type Pointer<T> = impl std::ops::Deref<Target=T>;
+
+fn test() -> Pointer<_> {
+    //~^ ERROR: the placeholder `_` is not allowed within types
+    Box::new(1)
+}
+
+fn main() {
+    test();
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-77179.stderr b/src/test/ui/type-alias-impl-trait/issue-77179.stderr
new file mode 100644
index 000000000..053546e4b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-77179.stderr
@@ -0,0 +1,12 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/issue-77179.rs:7:22
+   |
+LL | fn test() -> Pointer<_> {
+   |              --------^-
+   |              |       |
+   |              |       not allowed in type signatures
+   |              help: replace with the correct return type: `Pointer<i32>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-78450.rs b/src/test/ui/type-alias-impl-trait/issue-78450.rs
new file mode 100644
index 000000000..fccbfb74f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-78450.rs
@@ -0,0 +1,25 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+pub trait AssociatedImpl {
+    type ImplTrait;
+
+    fn f() -> Self::ImplTrait;
+}
+
+struct S<T>(T);
+
+trait Associated {
+    type A;
+}
+
+impl<'a, T: Associated<A = &'a ()>> AssociatedImpl for S<T> {
+    type ImplTrait = impl core::fmt::Debug;
+
+    fn f() -> Self::ImplTrait {
+        ()
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-84660-trait-impl-for-tait.rs b/src/test/ui/type-alias-impl-trait/issue-84660-trait-impl-for-tait.rs
new file mode 100644
index 000000000..fa25d8f76
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-84660-trait-impl-for-tait.rs
@@ -0,0 +1,23 @@
+// Regression test for issues #84660 and #86411: both are variations on #76202.
+// Tests that we don't ICE when we have an opaque type appearing anywhere in an impl header.
+
+#![feature(type_alias_impl_trait)]
+
+trait Foo {}
+impl Foo for () {}
+type Bar = impl Foo;
+fn _defining_use() -> Bar {}
+
+trait TraitArg<T> {
+    fn f();
+}
+
+impl TraitArg<Bar> for () { //~ ERROR cannot implement trait
+    fn f() {
+        println!("ho");
+    }
+}
+
+fn main() {
+    <() as TraitArg<Bar>>::f();
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-84660-trait-impl-for-tait.stderr b/src/test/ui/type-alias-impl-trait/issue-84660-trait-impl-for-tait.stderr
new file mode 100644
index 000000000..bb70d07be
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-84660-trait-impl-for-tait.stderr
@@ -0,0 +1,14 @@
+error: cannot implement trait on type alias impl trait
+  --> $DIR/issue-84660-trait-impl-for-tait.rs:15:15
+   |
+LL | impl TraitArg<Bar> for () {
+   |               ^^^
+   |
+note: type alias impl trait defined here
+  --> $DIR/issue-84660-trait-impl-for-tait.rs:8:12
+   |
+LL | type Bar = impl Foo;
+   |            ^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-84660-unsoundness.rs b/src/test/ui/type-alias-impl-trait/issue-84660-unsoundness.rs
new file mode 100644
index 000000000..f12d1b6d9
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-84660-unsoundness.rs
@@ -0,0 +1,41 @@
+// Another example from issue #84660, this time weaponized as a safe transmute: an opaque type in an
+// impl header being accepted was used to create unsoundness.
+
+#![feature(type_alias_impl_trait)]
+
+trait Foo {}
+impl Foo for () {}
+type Bar = impl Foo;
+fn _defining_use() -> Bar {}
+
+trait Trait<T, In> {
+    type Out;
+    fn convert(i: In) -> Self::Out;
+}
+
+impl<In, Out> Trait<Bar, In> for Out { //~ ERROR cannot implement trait
+    type Out = Out;
+    fn convert(_i: In) -> Self::Out {
+        unreachable!();
+    }
+}
+
+impl<In, Out> Trait<(), In> for Out {
+    type Out = In;
+    fn convert(i: In) -> Self::Out {
+        i
+    }
+}
+
+fn transmute<In, Out>(i: In) -> Out {
+    <Out as Trait<Bar, In>>::convert(i)
+}
+
+fn main() {
+    let d;
+    {
+        let x = "Hello World".to_string();
+        d = transmute::<&String, &String>(&x);
+    }
+    println!("{}", d);
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-84660-unsoundness.stderr b/src/test/ui/type-alias-impl-trait/issue-84660-unsoundness.stderr
new file mode 100644
index 000000000..f2d600fb4
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-84660-unsoundness.stderr
@@ -0,0 +1,14 @@
+error: cannot implement trait on type alias impl trait
+  --> $DIR/issue-84660-unsoundness.rs:16:21
+   |
+LL | impl<In, Out> Trait<Bar, In> for Out {
+   |                     ^^^
+   |
+note: type alias impl trait defined here
+  --> $DIR/issue-84660-unsoundness.rs:8:12
+   |
+LL | type Bar = impl Foo;
+   |            ^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/issue-87455-static-lifetime-ice.rs b/src/test/ui/type-alias-impl-trait/issue-87455-static-lifetime-ice.rs
new file mode 100644
index 000000000..80a74eb63
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-87455-static-lifetime-ice.rs
@@ -0,0 +1,73 @@
+// check-pass
+
+use std::error::Error as StdError;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+pub trait Stream {
+    type Item;
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>;
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+pub trait TryStream: Stream {
+    type Ok;
+    type Error;
+
+    fn try_poll_next(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Option<Result<Self::Ok, Self::Error>>>;
+}
+
+impl<S, T, E> TryStream for S
+where
+    S: ?Sized + Stream<Item = Result<T, E>>,
+{
+    type Ok = T;
+    type Error = E;
+
+    fn try_poll_next(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Option<Result<Self::Ok, Self::Error>>> {
+        self.poll_next(cx)
+    }
+}
+
+pub trait ServerSentEvent: Sized + Send + Sync + 'static {}
+
+impl<T: Send + Sync + 'static> ServerSentEvent for T {}
+
+struct SseKeepAlive<S> {
+    event_stream: S,
+}
+
+struct SseComment<T>(T);
+
+impl<S> Stream for SseKeepAlive<S>
+where
+    S: TryStream + Send + 'static,
+    S::Ok: ServerSentEvent,
+    S::Error: StdError + Send + Sync + 'static,
+{
+    type Item = Result<SseComment<&'static str>, ()>;
+    fn poll_next(self: Pin<&mut Self>, _cx: &mut Context) -> Poll<Option<Self::Item>> {
+        unimplemented!()
+    }
+}
+
+pub fn keep<S>(
+    event_stream: S,
+) -> impl TryStream<Ok = impl ServerSentEvent + Send + 'static, Error = ()> + Send + 'static
+where
+    S: TryStream + Send + 'static,
+    S::Ok: ServerSentEvent + Send,
+    S::Error: StdError + Send + Sync + 'static,
+{
+    SseKeepAlive { event_stream }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-89686.rs b/src/test/ui/type-alias-impl-trait/issue-89686.rs
new file mode 100644
index 000000000..de070fc9d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-89686.rs
@@ -0,0 +1,23 @@
+// edition:2018
+
+#![feature(type_alias_impl_trait)]
+
+use std::future::Future;
+
+type G<'a, T> = impl Future<Output = ()>;
+
+trait Trait {
+    type F: Future<Output = ()>;
+
+    fn f(&self) -> Self::F;
+
+    fn g<'a>(&'a self) -> G<'a, Self>
+    where
+        Self: Sized,
+    {
+        async move { self.f().await }
+        //~^ ERROR: the trait bound `T: Trait` is not satisfied
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-89686.stderr b/src/test/ui/type-alias-impl-trait/issue-89686.stderr
new file mode 100644
index 000000000..b636ada8b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-89686.stderr
@@ -0,0 +1,14 @@
+error[E0277]: the trait bound `T: Trait` is not satisfied
+  --> $DIR/issue-89686.rs:18:9
+   |
+LL |         async move { self.f().await }
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Trait` is not implemented for `T`
+   |
+help: consider restricting type parameter `T`
+   |
+LL | type G<'a, T: Trait> = impl Future<Output = ()>;
+   |             +++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-89952.rs b/src/test/ui/type-alias-impl-trait/issue-89952.rs
new file mode 100644
index 000000000..dc0f19c04
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-89952.rs
@@ -0,0 +1,31 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+trait SomeTrait {}
+impl SomeTrait for () {}
+
+trait MyFuture {
+    type Output;
+}
+impl<T> MyFuture for T {
+    type Output = T;
+}
+
+trait ReturnsFuture {
+    type Output: SomeTrait;
+    type Future: MyFuture<Output = Result<Self::Output, ()>>;
+    fn func() -> Self::Future;
+}
+
+struct Foo;
+
+impl ReturnsFuture for Foo {
+    type Output = impl SomeTrait;
+    type Future = impl MyFuture<Output = Result<Self::Output, ()>>;
+    fn func() -> Self::Future {
+        Result::<(), ()>::Err(())
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-90400-1.rs b/src/test/ui/type-alias-impl-trait/issue-90400-1.rs
new file mode 100644
index 000000000..8550a3e86
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-90400-1.rs
@@ -0,0 +1,30 @@
+// Regression test for #90400,
+// taken from https://github.com/rust-lang/rust/issues/90400#issuecomment-954927836
+
+#![feature(generic_associated_types)]
+#![feature(type_alias_impl_trait)]
+
+trait Bar {
+    fn bar(&self);
+}
+
+trait Foo {
+    type FooFn<B>: FnOnce();
+
+    fn foo<B: Bar>(&self, bar: B) -> Self::FooFn<B>;
+}
+
+struct MyFoo;
+
+impl Foo for MyFoo {
+    type FooFn<B> = impl FnOnce();
+
+    fn foo<B: Bar>(&self, bar: B) -> Self::FooFn<B> {
+        move || bar.bar() //~ ERROR: the trait bound `B: Bar` is not satisfied
+    }
+}
+
+fn main() {
+    let boom: <MyFoo as Foo>::FooFn<u32> = unsafe { core::mem::zeroed() };
+    boom();
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-90400-1.stderr b/src/test/ui/type-alias-impl-trait/issue-90400-1.stderr
new file mode 100644
index 000000000..428a10740
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-90400-1.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the trait bound `B: Bar` is not satisfied
+  --> $DIR/issue-90400-1.rs:23:9
+   |
+LL |         move || bar.bar()
+   |         ^^^^^^^^^^^^^^^^^ the trait `Bar` is not implemented for `B`
+   |
+note: required by a bound in `<MyFoo as Foo>::foo`
+  --> $DIR/issue-90400-1.rs:22:15
+   |
+LL |     fn foo<B: Bar>(&self, bar: B) -> Self::FooFn<B> {
+   |               ^^^ required by this bound in `<MyFoo as Foo>::foo`
+help: consider restricting type parameter `B`
+   |
+LL |     type FooFn<B: Bar> = impl FnOnce();
+   |                 +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-90400-2.rs b/src/test/ui/type-alias-impl-trait/issue-90400-2.rs
new file mode 100644
index 000000000..2b369bb8a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-90400-2.rs
@@ -0,0 +1,38 @@
+// Regression test for #90400,
+// taken from https://github.com/rust-lang/rust/issues/90400#issuecomment-954927836
+
+#![feature(generic_associated_types)]
+#![feature(type_alias_impl_trait)]
+
+trait Bar {
+    fn bar(&self);
+}
+
+trait Baz {
+    fn baz(&self);
+}
+
+trait Foo {
+    type FooFn<B>: Baz;
+
+    fn foo<B: Bar>(&self, bar: B) -> Self::FooFn<B>;
+}
+
+struct MyFoo;
+impl Foo for MyFoo {
+    type FooFn<B> = impl Baz;
+
+    fn foo<B: Bar>(&self, bar: B) -> Self::FooFn<B> {
+        MyBaz(bar) //~ ERROR: the trait bound `B: Bar` is not satisfied
+    }
+}
+
+struct MyBaz<B: Bar>(B);
+impl<B: Bar> Baz for MyBaz<B> {
+    fn baz(&self) {}
+}
+
+fn main() {
+    let boom: <MyFoo as Foo>::FooFn<u32> = unsafe { core::mem::zeroed() };
+    boom.baz();
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-90400-2.stderr b/src/test/ui/type-alias-impl-trait/issue-90400-2.stderr
new file mode 100644
index 000000000..5da05a439
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-90400-2.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the trait bound `B: Bar` is not satisfied
+  --> $DIR/issue-90400-2.rs:26:9
+   |
+LL |         MyBaz(bar)
+   |         ^^^^^^^^^^ the trait `Bar` is not implemented for `B`
+   |
+note: required because of the requirements on the impl of `Baz` for `MyBaz<B>`
+  --> $DIR/issue-90400-2.rs:31:14
+   |
+LL | impl<B: Bar> Baz for MyBaz<B> {
+   |              ^^^     ^^^^^^^^
+help: consider restricting type parameter `B`
+   |
+LL |     type FooFn<B: Bar> = impl Baz;
+   |                 +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-93411.rs b/src/test/ui/type-alias-impl-trait/issue-93411.rs
new file mode 100644
index 000000000..1f8c78926
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-93411.rs
@@ -0,0 +1,19 @@
+#![feature(type_alias_impl_trait)]
+
+// this test used to stack overflow due to infinite recursion.
+// check-pass
+// compile-flags: --edition=2018
+
+use std::future::Future;
+
+fn main() {
+    let _ = move || async move {
+        let value = 0u8;
+        blah(&value).await;
+    };
+}
+
+type BlahFut<'a> = impl Future<Output = ()> + Send + 'a;
+fn blah<'a>(_value: &'a u8) -> BlahFut<'a> {
+    async {}
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-94429.rs b/src/test/ui/type-alias-impl-trait/issue-94429.rs
new file mode 100644
index 000000000..2c965b875
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-94429.rs
@@ -0,0 +1,23 @@
+#![feature(type_alias_impl_trait, generator_trait, generators)]
+use std::ops::Generator;
+
+trait Runnable {
+    type Gen: Generator<Yield = (), Return = ()>;
+
+    fn run(&mut self) -> Self::Gen;
+}
+
+struct Implementor {}
+
+impl Runnable for Implementor {
+    type Gen = impl Generator<Yield = (), Return = ()>;
+
+    fn run(&mut self) -> Self::Gen {
+    //~^ ERROR: type mismatch resolving
+        move || {
+            yield 1;
+        }
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-94429.stderr b/src/test/ui/type-alias-impl-trait/issue-94429.stderr
new file mode 100644
index 000000000..8d7f7a07b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-94429.stderr
@@ -0,0 +1,9 @@
+error[E0271]: type mismatch resolving `<[generator@$DIR/issue-94429.rs:17:9: 17:16] as Generator>::Yield == ()`
+  --> $DIR/issue-94429.rs:15:26
+   |
+LL |     fn run(&mut self) -> Self::Gen {
+   |                          ^^^^^^^^^ expected integer, found `()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-98604.rs b/src/test/ui/type-alias-impl-trait/issue-98604.rs
new file mode 100644
index 000000000..a4fd8a82a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-98604.rs
@@ -0,0 +1,13 @@
+// edition:2018
+
+type AsyncFnPtr = Box<
+    dyn Fn() -> std::pin::Pin<Box<dyn std::future::Future<Output = ()>>>,
+>;
+
+async fn test() {}
+
+#[allow(unused_must_use)]
+fn main() {
+    Box::new(test) as AsyncFnPtr;
+    //~^ ERROR type mismatch
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-98604.stderr b/src/test/ui/type-alias-impl-trait/issue-98604.stderr
new file mode 100644
index 000000000..f04d1b4d7
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-98604.stderr
@@ -0,0 +1,18 @@
+error[E0271]: type mismatch resolving `<fn() -> impl Future<Output = ()> {test} as FnOnce<()>>::Output == Pin<Box<(dyn Future<Output = ()> + 'static)>>`
+  --> $DIR/issue-98604.rs:11:5
+   |
+LL |     Box::new(test) as AsyncFnPtr;
+   |     ^^^^^^^^^^^^^^ expected struct `Pin`, found opaque type
+   |
+note: while checking the return type of the `async fn`
+  --> $DIR/issue-98604.rs:7:17
+   |
+LL | async fn test() {}
+   |                 ^ checked the `Output` of this `async fn`, found opaque type
+   = note:   expected struct `Pin<Box<(dyn Future<Output = ()> + 'static)>>`
+           found opaque type `impl Future<Output = ()>`
+   = note: required for the cast from `fn() -> impl Future<Output = ()> {test}` to the object type `dyn Fn() -> Pin<Box<(dyn Future<Output = ()> + 'static)>>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/src/test/ui/type-alias-impl-trait/issue-98608.rs b/src/test/ui/type-alias-impl-trait/issue-98608.rs
new file mode 100644
index 000000000..d75762a8b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-98608.rs
@@ -0,0 +1,9 @@
+fn hi() -> impl Sized { std::ptr::null::<u8>() }
+
+fn main() {
+    let b: Box<dyn Fn() -> Box<u8>> = Box::new(hi);
+    //~^ ERROR type mismatch resolving `<fn() -> impl Sized {hi} as FnOnce<()>>::Output == Box<u8>`
+    let boxed = b();
+    let null = *boxed;
+    println!("{null:?}");
+}
diff --git a/src/test/ui/type-alias-impl-trait/issue-98608.stderr b/src/test/ui/type-alias-impl-trait/issue-98608.stderr
new file mode 100644
index 000000000..8f3ec7d9d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-98608.stderr
@@ -0,0 +1,16 @@
+error[E0271]: type mismatch resolving `<fn() -> impl Sized {hi} as FnOnce<()>>::Output == Box<u8>`
+  --> $DIR/issue-98608.rs:4:39
+   |
+LL | fn hi() -> impl Sized { std::ptr::null::<u8>() }
+   |            ---------- the found opaque type
+...
+LL |     let b: Box<dyn Fn() -> Box<u8>> = Box::new(hi);
+   |                                       ^^^^^^^^^^^^ expected struct `Box`, found opaque type
+   |
+   = note:   expected struct `Box<u8>`
+           found opaque type `impl Sized`
+   = note: required for the cast from `fn() -> impl Sized {hi}` to the object type `dyn Fn() -> Box<u8>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-infer.rs b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-infer.rs
new file mode 100644
index 000000000..b887fcf30
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-infer.rs
@@ -0,0 +1,13 @@
+// https://github.com/rust-lang/rust/issues/73481
+// This test used to cause unsoundness, since one of the two possible
+// resolutions was chosen at random instead of erroring due to conflicts.
+
+#![feature(type_alias_impl_trait)]
+
+type Y<A, B> = impl std::fmt::Debug;
+
+fn g<A, B>() -> (Y<A, B>, Y<B, A>) {
+    (42_i64, 60) //~ ERROR concrete type differs from previous defining opaque type use
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-infer.stderr b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-infer.stderr
new file mode 100644
index 000000000..278117009
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-infer.stderr
@@ -0,0 +1,11 @@
+error: concrete type differs from previous defining opaque type use
+  --> $DIR/multiple-def-uses-in-one-fn-infer.rs:10:5
+   |
+LL |     (42_i64, 60)
+   |     ^^^^^^^^^^^^
+   |     |
+   |     expected `i64`, got `i32`
+   |     this expression supplies two conflicting concrete types for the same opaque type
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-lifetimes.rs b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-lifetimes.rs
new file mode 100644
index 000000000..3f122f106
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-lifetimes.rs
@@ -0,0 +1,9 @@
+#![feature(type_alias_impl_trait)]
+
+type Foo<'a, 'b> = impl std::fmt::Debug;
+
+fn foo<'x, 'y>(i: &'x i32, j: &'y i32) -> (Foo<'x, 'y>, Foo<'y, 'x>) {
+    (i, i) //~ ERROR concrete type differs from previous
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-lifetimes.stderr b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-lifetimes.stderr
new file mode 100644
index 000000000..81e603e23
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-lifetimes.stderr
@@ -0,0 +1,11 @@
+error: concrete type differs from previous defining opaque type use
+  --> $DIR/multiple-def-uses-in-one-fn-lifetimes.rs:6:5
+   |
+LL |     (i, i)
+   |     ^^^^^^
+   |     |
+   |     expected `&'a i32`, got `&'b i32`
+   |     this expression supplies two conflicting concrete types for the same opaque type
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-pass.rs b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-pass.rs
new file mode 100644
index 000000000..83fd9a1da
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn-pass.rs
@@ -0,0 +1,21 @@
+// check-pass
+#![feature(type_alias_impl_trait)]
+
+type X<A: ToString + Clone, B: ToString + Clone> = impl ToString;
+
+fn f<A: ToString + Clone, B: ToString + Clone>(a: A, b: B) -> (X<A, B>, X<A, B>) {
+    (a.clone(), a)
+}
+
+type Foo<'a, 'b> = impl std::fmt::Debug;
+
+fn foo<'x, 'y>(i: &'x i32, j: &'y i32) -> (Foo<'x, 'y>, Foo<'y, 'x>) {
+    (i, j)
+}
+
+fn main() {
+    println!("{}", <X<_, _> as ToString>::to_string(&f(42_i32, String::new()).1));
+    let meh = 42;
+    let muh = 69;
+    println!("{:?}", foo(&meh, &muh));
+}
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn.rs b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn.rs
new file mode 100644
index 000000000..da845e861
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn.rs
@@ -0,0 +1,16 @@
+// https://github.com/rust-lang/rust/issues/73481
+// This test used to cause unsoundness, since one of the two possible
+// resolutions was chosen at random instead of erroring due to conflicts.
+
+#![feature(type_alias_impl_trait)]
+
+type X<A, B> = impl Into<&'static A>;
+
+fn f<A, B: 'static>(a: &'static A, b: B) -> (X<A, B>, X<B, A>) {
+    //~^ ERROR the trait bound `&'static B: From<&A>` is not satisfied
+    (a, a)
+}
+
+fn main() {
+    println!("{}", <X<_, _> as Into<&String>>::into(f(&[1isize, 2, 3], String::new()).1));
+}
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn.stderr b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn.stderr
new file mode 100644
index 000000000..cdaae99e2
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn.stderr
@@ -0,0 +1,15 @@
+error[E0277]: the trait bound `&'static B: From<&A>` is not satisfied
+  --> $DIR/multiple-def-uses-in-one-fn.rs:9:45
+   |
+LL | fn f<A, B: 'static>(a: &'static A, b: B) -> (X<A, B>, X<B, A>) {
+   |                                             ^^^^^^^^^^^^^^^^^^ the trait `From<&A>` is not implemented for `&'static B`
+   |
+   = note: required because of the requirements on the impl of `Into<&'static B>` for `&A`
+help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
+   |
+LL | fn f<A, B: 'static>(a: &'static A, b: B) -> (X<A, B>, X<B, A>) where &'static B: From<&A> {
+   |                                                                ++++++++++++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn2.rs b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn2.rs
new file mode 100644
index 000000000..14510a529
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn2.rs
@@ -0,0 +1,16 @@
+// https://github.com/rust-lang/rust/issues/73481
+// This test used to cause unsoundness, since one of the two possible
+// resolutions was chosen at random instead of erroring due to conflicts.
+
+#![feature(type_alias_impl_trait)]
+
+type X<A: ToString + Clone, B: ToString + Clone> = impl ToString;
+
+fn f<A: ToString + Clone, B: ToString + Clone>(a: A, b: B) -> (X<A, B>, X<B, A>) {
+    (a.clone(), a)
+    //~^ ERROR concrete type differs from previous defining opaque type
+}
+
+fn main() {
+    println!("{}", <X<_, _> as ToString>::to_string(&f(42_i32, String::new()).1));
+}
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn2.stderr b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn2.stderr
new file mode 100644
index 000000000..0f752212a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn2.stderr
@@ -0,0 +1,11 @@
+error: concrete type differs from previous defining opaque type use
+  --> $DIR/multiple-def-uses-in-one-fn2.rs:10:5
+   |
+LL |     (a.clone(), a)
+   |     ^^^^^^^^^^^^^^
+   |     |
+   |     expected `A`, got `B`
+   |     this expression supplies two conflicting concrete types for the same opaque type
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn3.rs b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn3.rs
new file mode 100644
index 000000000..11a922443
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn3.rs
@@ -0,0 +1,18 @@
+// https://github.com/rust-lang/rust/issues/73481
+// This test used to cause unsoundness, since one of the two possible
+// resolutions was chosen at random instead of erroring due to conflicts.
+
+#![feature(type_alias_impl_trait)]
+
+type X<A: ToString + Clone, B: ToString + Clone> = impl ToString;
+
+fn f<A: ToString + Clone, B: ToString + Clone>(a: A, b: B) -> (X<A, B>, X<B, A>) {
+    (a, b)
+}
+
+fn g<A: ToString + Clone, B: ToString + Clone>(a: A, b: B) -> (X<A, B>, X<A, B>) {
+    (a, b)
+    //~^ ERROR mismatched types
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn3.stderr b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn3.stderr
new file mode 100644
index 000000000..bbe709dcc
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple-def-uses-in-one-fn3.stderr
@@ -0,0 +1,18 @@
+error[E0308]: mismatched types
+  --> $DIR/multiple-def-uses-in-one-fn3.rs:14:9
+   |
+LL | fn g<A: ToString + Clone, B: ToString + Clone>(a: A, b: B) -> (X<A, B>, X<A, B>) {
+   |      -                    - found type parameter
+   |      |
+   |      expected type parameter
+LL |     (a, b)
+   |         ^ expected type parameter `A`, found type parameter `B`
+   |
+   = note: expected type parameter `A`
+              found type parameter `B`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type-alias-impl-trait/multiple_definitions.rs b/src/test/ui/type-alias-impl-trait/multiple_definitions.rs
new file mode 100644
index 000000000..9e6268e63
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/multiple_definitions.rs
@@ -0,0 +1,30 @@
+// check-pass
+
+use std::marker::PhantomData;
+
+pub struct ConcreteError {}
+pub trait IoBase {}
+struct X {}
+impl IoBase for X {}
+
+pub struct ClusterIterator<B, E, S = B> {
+    pub fat: B,
+    phantom_s: PhantomData<S>,
+    phantom_e: PhantomData<E>,
+}
+
+pub struct FileSystem<IO: IoBase> {
+    pub disk: IO,
+}
+
+impl<IO: IoBase> FileSystem<IO> {
+    pub fn cluster_iter(&self) -> ClusterIterator<impl IoBase + '_, ConcreteError> {
+        ClusterIterator {
+            fat: X {},
+            phantom_s: PhantomData::default(),
+            phantom_e: PhantomData::default(),
+        }
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/nested-tait-inference.rs b/src/test/ui/type-alias-impl-trait/nested-tait-inference.rs
new file mode 100644
index 000000000..822489716
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/nested-tait-inference.rs
@@ -0,0 +1,18 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+use std::fmt::Debug;
+
+type FooX = impl Debug;
+
+trait Foo<A> { }
+
+impl Foo<()> for () { }
+
+fn foo() -> impl Foo<FooX> {
+    //~^ ERROR: the trait bound `(): Foo<FooX>` is not satisfied
+    // FIXME(type-alias-impl-trait): We could probably make this work.
+    ()
+}
+
+fn main() { }
diff --git a/src/test/ui/type-alias-impl-trait/nested-tait-inference.stderr b/src/test/ui/type-alias-impl-trait/nested-tait-inference.stderr
new file mode 100644
index 000000000..62db019ed
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/nested-tait-inference.stderr
@@ -0,0 +1,14 @@
+error[E0277]: the trait bound `(): Foo<FooX>` is not satisfied
+  --> $DIR/nested-tait-inference.rs:12:13
+   |
+LL | fn foo() -> impl Foo<FooX> {
+   |             ^^^^^^^^^^^^^^ the trait `Foo<FooX>` is not implemented for `()`
+...
+LL |     ()
+   |     -- return type was inferred to be `()` here
+   |
+   = help: the trait `Foo<()>` is implemented for `()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/nested-tait-inference2.rs b/src/test/ui/type-alias-impl-trait/nested-tait-inference2.rs
new file mode 100644
index 000000000..0d7f5bad2
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/nested-tait-inference2.rs
@@ -0,0 +1,18 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+use std::fmt::Debug;
+
+type FooX = impl Debug;
+
+trait Foo<A> {}
+
+impl Foo<()> for () {}
+impl Foo<u32> for () {}
+
+fn foo() -> impl Foo<FooX> {
+    //~^ ERROR: the trait bound `(): Foo<FooX>` is not satisfied
+    ()
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/nested-tait-inference2.stderr b/src/test/ui/type-alias-impl-trait/nested-tait-inference2.stderr
new file mode 100644
index 000000000..f4d96038d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/nested-tait-inference2.stderr
@@ -0,0 +1,16 @@
+error[E0277]: the trait bound `(): Foo<FooX>` is not satisfied
+  --> $DIR/nested-tait-inference2.rs:13:13
+   |
+LL | fn foo() -> impl Foo<FooX> {
+   |             ^^^^^^^^^^^^^^ the trait `Foo<FooX>` is not implemented for `()`
+LL |
+LL |     ()
+   |     -- return type was inferred to be `()` here
+   |
+   = help: the following other types implement trait `Foo<A>`:
+             <() as Foo<()>>
+             <() as Foo<u32>>
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/nested-tait-inference3.rs b/src/test/ui/type-alias-impl-trait/nested-tait-inference3.rs
new file mode 100644
index 000000000..ebf3a99bb
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/nested-tait-inference3.rs
@@ -0,0 +1,17 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+use std::fmt::Debug;
+
+type FooX = impl Debug;
+
+trait Foo<A> { }
+
+impl Foo<FooX> for () { }
+//~^ cannot implement trait on type alias impl trait
+
+fn foo() -> impl Foo<FooX> {
+    ()
+}
+
+fn main() { }
diff --git a/src/test/ui/type-alias-impl-trait/nested-tait-inference3.stderr b/src/test/ui/type-alias-impl-trait/nested-tait-inference3.stderr
new file mode 100644
index 000000000..4a3fb1673
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/nested-tait-inference3.stderr
@@ -0,0 +1,14 @@
+error: cannot implement trait on type alias impl trait
+  --> $DIR/nested-tait-inference3.rs:10:10
+   |
+LL | impl Foo<FooX> for () { }
+   |          ^^^^
+   |
+note: type alias impl trait defined here
+  --> $DIR/nested-tait-inference3.rs:6:13
+   |
+LL | type FooX = impl Debug;
+   |             ^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/nested.rs b/src/test/ui/type-alias-impl-trait/nested.rs
new file mode 100644
index 000000000..6b866be7d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/nested.rs
@@ -0,0 +1,17 @@
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl std::fmt::Debug;
+type Bar = impl Trait<Foo>;
+
+trait Trait<T> {}
+
+impl<T, U> Trait<T> for U {}
+
+fn bar() -> Bar {
+    42
+}
+
+fn main() {
+    println!("{:?}", bar());
+    //~^ ERROR `Bar` doesn't implement `Debug`
+}
diff --git a/src/test/ui/type-alias-impl-trait/nested.stderr b/src/test/ui/type-alias-impl-trait/nested.stderr
new file mode 100644
index 000000000..732af5c0b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/nested.stderr
@@ -0,0 +1,12 @@
+error[E0277]: `Bar` doesn't implement `Debug`
+  --> $DIR/nested.rs:15:22
+   |
+LL |     println!("{:?}", bar());
+   |                      ^^^^^ `Bar` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = help: the trait `Debug` is not implemented for `Bar`
+   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/nested_type_alias_impl_trait.rs b/src/test/ui/type-alias-impl-trait/nested_type_alias_impl_trait.rs
new file mode 100644
index 000000000..60b6e1aac
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/nested_type_alias_impl_trait.rs
@@ -0,0 +1,20 @@
+#![feature(type_alias_impl_trait)]
+
+mod my_mod {
+    use std::fmt::Debug;
+
+    pub type Foo = impl Debug;
+    pub type Foot = impl Debug;
+
+    pub fn get_foo() -> Foo {
+        5i32
+    }
+
+    pub fn get_foot() -> Foot {
+        get_foo() //~ ERROR opaque type's hidden type cannot be another opaque type
+    }
+}
+
+fn main() {
+    let _: my_mod::Foot = my_mod::get_foot();
+}
diff --git a/src/test/ui/type-alias-impl-trait/nested_type_alias_impl_trait.stderr b/src/test/ui/type-alias-impl-trait/nested_type_alias_impl_trait.stderr
new file mode 100644
index 000000000..fa6ecf68d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/nested_type_alias_impl_trait.stderr
@@ -0,0 +1,19 @@
+error: opaque type's hidden type cannot be another opaque type from the same scope
+  --> $DIR/nested_type_alias_impl_trait.rs:14:9
+   |
+LL |         get_foo()
+   |         ^^^^^^^^^ one of the two opaque types used here has to be outside its defining scope
+   |
+note: opaque type whose hidden type is being assigned
+  --> $DIR/nested_type_alias_impl_trait.rs:7:21
+   |
+LL |     pub type Foot = impl Debug;
+   |                     ^^^^^^^^^^
+note: opaque type being used as hidden type
+  --> $DIR/nested_type_alias_impl_trait.rs:6:20
+   |
+LL |     pub type Foo = impl Debug;
+   |                    ^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/never_reveal_concrete_type.rs b/src/test/ui/type-alias-impl-trait/never_reveal_concrete_type.rs
new file mode 100644
index 000000000..fed5ac07c
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/never_reveal_concrete_type.rs
@@ -0,0 +1,14 @@
+#![feature(type_alias_impl_trait)]
+// check-pass
+fn main() {}
+
+type NoReveal = impl std::fmt::Debug;
+
+fn define_no_reveal() -> NoReveal {
+    ""
+}
+
+fn no_reveal(x: NoReveal) {
+    let _: &'static str = x;
+    let _ = x as &'static str;
+}
diff --git a/src/test/ui/type-alias-impl-trait/no_inferrable_concrete_type.rs b/src/test/ui/type-alias-impl-trait/no_inferrable_concrete_type.rs
new file mode 100644
index 000000000..46621362e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/no_inferrable_concrete_type.rs
@@ -0,0 +1,19 @@
+// Issue 52985: user code provides no use case that allows a type alias `impl Trait`
+// We now emit a 'unconstrained opaque type' error
+
+#![feature(type_alias_impl_trait)]
+
+mod foo {
+    pub type Foo = impl Copy;
+    //~^ ERROR unconstrained opaque type
+
+    // make compiler happy about using 'Foo'
+    pub fn bar(x: Foo) -> Foo {
+        x
+    }
+}
+
+fn main() {
+    let _: foo::Foo = std::mem::transmute(0u8);
+    //~^ ERROR cannot transmute between types of different sizes, or dependently-sized types
+}
diff --git a/src/test/ui/type-alias-impl-trait/no_inferrable_concrete_type.stderr b/src/test/ui/type-alias-impl-trait/no_inferrable_concrete_type.stderr
new file mode 100644
index 000000000..337708b87
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/no_inferrable_concrete_type.stderr
@@ -0,0 +1,20 @@
+error: unconstrained opaque type
+  --> $DIR/no_inferrable_concrete_type.rs:7:20
+   |
+LL |     pub type Foo = impl Copy;
+   |                    ^^^^^^^^^
+   |
+   = note: `Foo` must be used in combination with a concrete type within the same module
+
+error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
+  --> $DIR/no_inferrable_concrete_type.rs:17:23
+   |
+LL |     let _: foo::Foo = std::mem::transmute(0u8);
+   |                       ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: source type: `u8` (8 bits)
+   = note: target type: `Foo` (size can vary because of [type error])
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0512`.
diff --git a/src/test/ui/type-alias-impl-trait/no_revealing_outside_defining_module.rs b/src/test/ui/type-alias-impl-trait/no_revealing_outside_defining_module.rs
new file mode 100644
index 000000000..61153b1e1
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/no_revealing_outside_defining_module.rs
@@ -0,0 +1,24 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+mod boo {
+    pub type Boo = impl ::std::fmt::Debug;
+    fn bomp() -> Boo {
+        ""
+    }
+}
+
+// We don't actually know the type here.
+
+fn bomp2() {
+    let _: &str = bomp(); //~ ERROR mismatched types
+}
+
+fn bomp() -> boo::Boo {
+    "" //~ ERROR mismatched types
+}
+
+fn bomp_loop() -> boo::Boo {
+    loop {}
+}
diff --git a/src/test/ui/type-alias-impl-trait/no_revealing_outside_defining_module.stderr b/src/test/ui/type-alias-impl-trait/no_revealing_outside_defining_module.stderr
new file mode 100644
index 000000000..ae03a5b3e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/no_revealing_outside_defining_module.stderr
@@ -0,0 +1,31 @@
+error[E0308]: mismatched types
+  --> $DIR/no_revealing_outside_defining_module.rs:15:19
+   |
+LL |     pub type Boo = impl ::std::fmt::Debug;
+   |                    ---------------------- the found opaque type
+...
+LL |     let _: &str = bomp();
+   |            ----   ^^^^^^ expected `&str`, found opaque type
+   |            |
+   |            expected due to this
+   |
+   = note: expected reference `&str`
+            found opaque type `Boo`
+
+error[E0308]: mismatched types
+  --> $DIR/no_revealing_outside_defining_module.rs:19:5
+   |
+LL |     pub type Boo = impl ::std::fmt::Debug;
+   |                    ---------------------- the expected opaque type
+...
+LL | fn bomp() -> boo::Boo {
+   |              -------- expected `Boo` because of return type
+LL |     ""
+   |     ^^ expected opaque type, found `&str`
+   |
+   = note: expected opaque type `Boo`
+                found reference `&'static str`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type-alias-impl-trait/not_a_defining_use.rs b/src/test/ui/type-alias-impl-trait/not_a_defining_use.rs
new file mode 100644
index 000000000..fa47d13f5
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/not_a_defining_use.rs
@@ -0,0 +1,36 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+type Two<T, U> = impl Debug;
+
+fn three<T: Debug, U>(t: T) -> Two<T, U> {
+    (t, 5i8)
+    //~^ ERROR `T` doesn't implement `Debug`
+}
+
+trait Bar {
+    type Blub: Debug;
+    const FOO: Self::Blub;
+}
+
+impl Bar for u32 {
+    type Blub = i32;
+    const FOO: i32 = 42;
+}
+
+fn four<T: Debug, U: Bar>(t: T) -> Two<T, U> {
+    (t, <U as Bar>::FOO)
+    //~^ ERROR `U: Bar` is not satisfied
+    //~| ERROR `T` doesn't implement `Debug`
+}
+
+fn is_sync<T: Sync>() {}
+
+fn asdfl() {
+    //FIXME(oli-obk): these currently cause cycle errors
+    //is_sync::<Two<i32, u32>>();
+    //is_sync::<Two<i32, *const i32>>();
+}
diff --git a/src/test/ui/type-alias-impl-trait/not_a_defining_use.stderr b/src/test/ui/type-alias-impl-trait/not_a_defining_use.stderr
new file mode 100644
index 000000000..a5ac38c38
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/not_a_defining_use.stderr
@@ -0,0 +1,38 @@
+error[E0277]: `T` doesn't implement `Debug`
+  --> $DIR/not_a_defining_use.rs:10:5
+   |
+LL |     (t, 5i8)
+   |     ^^^^^^^^ `T` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(T, i8)`
+help: consider restricting type parameter `T`
+   |
+LL | type Two<T: std::fmt::Debug, U> = impl Debug;
+   |           +++++++++++++++++
+
+error[E0277]: the trait bound `U: Bar` is not satisfied
+  --> $DIR/not_a_defining_use.rs:25:5
+   |
+LL |     (t, <U as Bar>::FOO)
+   |     ^^^^^^^^^^^^^^^^^^^^ the trait `Bar` is not implemented for `U`
+   |
+help: consider restricting type parameter `U`
+   |
+LL | type Two<T, U: Bar> = impl Debug;
+   |              +++++
+
+error[E0277]: `T` doesn't implement `Debug`
+  --> $DIR/not_a_defining_use.rs:25:5
+   |
+LL |     (t, <U as Bar>::FOO)
+   |     ^^^^^^^^^^^^^^^^^^^^ `T` cannot be formatted using `{:?}` because it doesn't implement `Debug`
+   |
+   = note: required because of the requirements on the impl of `Debug` for `(T, _)`
+help: consider restricting type parameter `T`
+   |
+LL | type Two<T: std::fmt::Debug, U> = impl Debug;
+   |           +++++++++++++++++
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/not_well_formed.rs b/src/test/ui/type-alias-impl-trait/not_well_formed.rs
new file mode 100644
index 000000000..fbb7a4d58
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/not_well_formed.rs
@@ -0,0 +1,17 @@
+#![feature(type_alias_impl_trait)]
+
+fn main() {}
+
+trait TraitWithAssoc {
+    type Assoc;
+}
+
+type Foo<V> = impl Trait<V::Assoc>; //~ associated type `Assoc` not found for `V`
+
+trait Trait<U> {}
+
+impl<W> Trait<W> for () {}
+
+fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T> {
+    ()
+}
diff --git a/src/test/ui/type-alias-impl-trait/not_well_formed.stderr b/src/test/ui/type-alias-impl-trait/not_well_formed.stderr
new file mode 100644
index 000000000..c36b95f47
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/not_well_formed.stderr
@@ -0,0 +1,9 @@
+error[E0220]: associated type `Assoc` not found for `V`
+  --> $DIR/not_well_formed.rs:9:29
+   |
+LL | type Foo<V> = impl Trait<V::Assoc>;
+   |                             ^^^^^ there is a similarly named associated type `Assoc` in the trait `TraitWithAssoc`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0220`.
diff --git a/src/test/ui/type-alias-impl-trait/reveal_local.rs b/src/test/ui/type-alias-impl-trait/reveal_local.rs
new file mode 100644
index 000000000..7ecb55353
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/reveal_local.rs
@@ -0,0 +1,25 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+type Foo = impl Debug;
+//~^ ERROR cycle detected
+
+fn is_send<T: Send>() { }
+
+fn not_good() {
+    // Error: this function does not constrain `Foo` to any particular
+    // hidden type, so it cannot rely on `Send` being true.
+    is_send::<Foo>();
+}
+
+fn not_gooder() {
+    // Constrain `Foo = u32`
+    let x: Foo = 22_u32;
+
+    // while we could know this from the hidden type, it would
+    // need extra roundabout logic to support it.
+    is_send::<Foo>();
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/reveal_local.stderr b/src/test/ui/type-alias-impl-trait/reveal_local.stderr
new file mode 100644
index 000000000..27fded333
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/reveal_local.stderr
@@ -0,0 +1,28 @@
+error[E0391]: cycle detected when computing type of `Foo::{opaque#0}`
+  --> $DIR/reveal_local.rs:5:12
+   |
+LL | type Foo = impl Debug;
+   |            ^^^^^^^^^^
+   |
+note: ...which requires type-checking `not_good`...
+  --> $DIR/reveal_local.rs:13:5
+   |
+LL |     is_send::<Foo>();
+   |     ^^^^^^^^^^^^^^
+   = note: ...which requires evaluating trait selection obligation `Foo: core::marker::Send`...
+   = note: ...which again requires computing type of `Foo::{opaque#0}`, completing the cycle
+note: cycle used when checking item types in top-level module
+  --> $DIR/reveal_local.rs:1:1
+   |
+LL | / #![feature(type_alias_impl_trait)]
+LL | |
+LL | | use std::fmt::Debug;
+LL | |
+...  |
+LL | |
+LL | | fn main() {}
+   | |____________^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0391`.
diff --git a/src/test/ui/type-alias-impl-trait/self-referential-2.rs b/src/test/ui/type-alias-impl-trait/self-referential-2.rs
new file mode 100644
index 000000000..8781196c3
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/self-referential-2.rs
@@ -0,0 +1,10 @@
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl std::fmt::Debug;
+type Bar = impl PartialEq<Foo>;
+
+fn bar() -> Bar {
+    42_i32 //~^ ERROR can't compare `i32` with `Foo`
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/self-referential-2.stderr b/src/test/ui/type-alias-impl-trait/self-referential-2.stderr
new file mode 100644
index 000000000..2b505d307
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/self-referential-2.stderr
@@ -0,0 +1,23 @@
+error[E0277]: can't compare `i32` with `Foo`
+  --> $DIR/self-referential-2.rs:6:13
+   |
+LL | fn bar() -> Bar {
+   |             ^^^ no implementation for `i32 == Foo`
+LL |     42_i32
+   |     ------ return type was inferred to be `i32` here
+   |
+   = help: the trait `PartialEq<Foo>` is not implemented for `i32`
+   = help: the following other types implement trait `PartialEq<Rhs>`:
+             f32
+             f64
+             i128
+             i16
+             i32
+             i64
+             i8
+             isize
+           and 6 others
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/self-referential-3.rs b/src/test/ui/type-alias-impl-trait/self-referential-3.rs
new file mode 100644
index 000000000..d40715717
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/self-referential-3.rs
@@ -0,0 +1,14 @@
+// run-pass
+#![feature(type_alias_impl_trait)]
+
+type Bar<'a, 'b> = impl PartialEq<Bar<'a, 'b>> + std::fmt::Debug;
+
+fn bar<'a, 'b>(i: &'a i32) -> Bar<'a, 'b> {
+    i
+}
+
+fn main() {
+    let meh = 42;
+    let muh = 42;
+    assert_eq!(bar(&meh), bar(&muh));
+}
diff --git a/src/test/ui/type-alias-impl-trait/self-referential-4.rs b/src/test/ui/type-alias-impl-trait/self-referential-4.rs
new file mode 100644
index 000000000..36742c8ad
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/self-referential-4.rs
@@ -0,0 +1,25 @@
+#![feature(type_alias_impl_trait)]
+
+type Bar<'a, 'b> = impl PartialEq<Bar<'b, 'static>> + std::fmt::Debug;
+
+fn bar<'a, 'b>(i: &'a i32) -> Bar<'a, 'b> {
+    i //~^ ERROR can't compare `&i32` with `Bar<'b, 'static>`
+}
+
+type Foo<'a, 'b> = impl PartialEq<Foo<'static, 'b>> + std::fmt::Debug;
+
+fn foo<'a, 'b>(i: &'a i32) -> Foo<'a, 'b> {
+    i //~^ ERROR can't compare `&i32` with `Foo<'static, 'b>`
+}
+
+type Moo<'a, 'b> = impl PartialEq<Moo<'static, 'a>> + std::fmt::Debug;
+
+fn moo<'a, 'b>(i: &'a i32) -> Moo<'a, 'b> {
+    i //~^ ERROR can't compare `&i32` with `Moo<'static, 'a>`
+}
+
+fn main() {
+    let meh = 42;
+    let muh = 69;
+    assert_eq!(bar(&meh), bar(&meh));
+}
diff --git a/src/test/ui/type-alias-impl-trait/self-referential-4.stderr b/src/test/ui/type-alias-impl-trait/self-referential-4.stderr
new file mode 100644
index 000000000..27880f792
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/self-referential-4.stderr
@@ -0,0 +1,63 @@
+error[E0277]: can't compare `&i32` with `Bar<'b, 'static>`
+  --> $DIR/self-referential-4.rs:5:31
+   |
+LL | fn bar<'a, 'b>(i: &'a i32) -> Bar<'a, 'b> {
+   |                               ^^^^^^^^^^^ no implementation for `&i32 == Bar<'b, 'static>`
+LL |     i
+   |     - return type was inferred to be `&i32` here
+   |
+   = help: the trait `PartialEq<Bar<'b, 'static>>` is not implemented for `&i32`
+   = help: the following other types implement trait `PartialEq<Rhs>`:
+             f32
+             f64
+             i128
+             i16
+             i32
+             i64
+             i8
+             isize
+           and 6 others
+
+error[E0277]: can't compare `&i32` with `Foo<'static, 'b>`
+  --> $DIR/self-referential-4.rs:11:31
+   |
+LL | fn foo<'a, 'b>(i: &'a i32) -> Foo<'a, 'b> {
+   |                               ^^^^^^^^^^^ no implementation for `&i32 == Foo<'static, 'b>`
+LL |     i
+   |     - return type was inferred to be `&i32` here
+   |
+   = help: the trait `PartialEq<Foo<'static, 'b>>` is not implemented for `&i32`
+   = help: the following other types implement trait `PartialEq<Rhs>`:
+             f32
+             f64
+             i128
+             i16
+             i32
+             i64
+             i8
+             isize
+           and 6 others
+
+error[E0277]: can't compare `&i32` with `Moo<'static, 'a>`
+  --> $DIR/self-referential-4.rs:17:31
+   |
+LL | fn moo<'a, 'b>(i: &'a i32) -> Moo<'a, 'b> {
+   |                               ^^^^^^^^^^^ no implementation for `&i32 == Moo<'static, 'a>`
+LL |     i
+   |     - return type was inferred to be `&i32` here
+   |
+   = help: the trait `PartialEq<Moo<'static, 'a>>` is not implemented for `&i32`
+   = help: the following other types implement trait `PartialEq<Rhs>`:
+             f32
+             f64
+             i128
+             i16
+             i32
+             i64
+             i8
+             isize
+           and 6 others
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/self-referential.rs b/src/test/ui/type-alias-impl-trait/self-referential.rs
new file mode 100644
index 000000000..3ff5406a3
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/self-referential.rs
@@ -0,0 +1,28 @@
+#![feature(type_alias_impl_trait)]
+
+type Bar<'a, 'b> = impl PartialEq<Bar<'b, 'a>> + std::fmt::Debug;
+
+fn bar<'a, 'b>(i: &'a i32) -> Bar<'a, 'b> {
+    //~^ ERROR can't compare `&i32` with `Bar<'b, 'a>`
+    i
+}
+
+type Foo<'a, 'b> = (i32, impl PartialEq<Foo<'a, 'b>> + std::fmt::Debug);
+
+fn foo<'a, 'b>(i: &'a i32) -> Foo<'a, 'b> {
+    //~^ ERROR can't compare `&i32` with `(i32, &i32)`
+    (42, i)
+}
+
+type Moo<'a, 'b> = (i32, impl PartialEq<Moo<'b, 'a>> + std::fmt::Debug);
+
+fn moo<'a, 'b>(i: &'a i32) -> Moo<'a, 'b> {
+    //~^ ERROR can't compare `&i32` with `(i32, Moo<'b, 'a>::{opaque#0})`
+    (42, i)
+}
+
+fn main() {
+    let meh = 42;
+    let muh = 69;
+    assert_eq!(bar(&meh), bar(&meh));
+}
diff --git a/src/test/ui/type-alias-impl-trait/self-referential.stderr b/src/test/ui/type-alias-impl-trait/self-referential.stderr
new file mode 100644
index 000000000..97d510f68
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/self-referential.stderr
@@ -0,0 +1,66 @@
+error[E0277]: can't compare `&i32` with `Bar<'b, 'a>`
+  --> $DIR/self-referential.rs:5:31
+   |
+LL | fn bar<'a, 'b>(i: &'a i32) -> Bar<'a, 'b> {
+   |                               ^^^^^^^^^^^ no implementation for `&i32 == Bar<'b, 'a>`
+LL |
+LL |     i
+   |     - return type was inferred to be `&i32` here
+   |
+   = help: the trait `PartialEq<Bar<'b, 'a>>` is not implemented for `&i32`
+   = help: the following other types implement trait `PartialEq<Rhs>`:
+             f32
+             f64
+             i128
+             i16
+             i32
+             i64
+             i8
+             isize
+           and 6 others
+
+error[E0277]: can't compare `&i32` with `(i32, &i32)`
+  --> $DIR/self-referential.rs:12:31
+   |
+LL | fn foo<'a, 'b>(i: &'a i32) -> Foo<'a, 'b> {
+   |                               ^^^^^^^^^^^ no implementation for `&i32 == (i32, &i32)`
+LL |
+LL |     (42, i)
+   |     ------- return type was inferred to be `(i32, &i32)` here
+   |
+   = help: the trait `PartialEq<(i32, &i32)>` is not implemented for `&i32`
+   = help: the following other types implement trait `PartialEq<Rhs>`:
+             f32
+             f64
+             i128
+             i16
+             i32
+             i64
+             i8
+             isize
+           and 6 others
+
+error[E0277]: can't compare `&i32` with `(i32, Moo<'b, 'a>::{opaque#0})`
+  --> $DIR/self-referential.rs:19:31
+   |
+LL | fn moo<'a, 'b>(i: &'a i32) -> Moo<'a, 'b> {
+   |                               ^^^^^^^^^^^ no implementation for `&i32 == (i32, Moo<'b, 'a>::{opaque#0})`
+LL |
+LL |     (42, i)
+   |     ------- return type was inferred to be `(i32, &i32)` here
+   |
+   = help: the trait `PartialEq<(i32, Moo<'b, 'a>::{opaque#0})>` is not implemented for `&i32`
+   = help: the following other types implement trait `PartialEq<Rhs>`:
+             f32
+             f64
+             i128
+             i16
+             i32
+             i64
+             i8
+             isize
+           and 6 others
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/static-const-types.rs b/src/test/ui/type-alias-impl-trait/static-const-types.rs
new file mode 100644
index 000000000..748a279e4
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/static-const-types.rs
@@ -0,0 +1,13 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+// check-pass
+
+use std::fmt::Debug;
+
+type Foo = impl Debug;
+
+static FOO1: Foo = 22_u32;
+const FOO2: Foo = 22_u32;
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/structural-match-no-leak.rs b/src/test/ui/type-alias-impl-trait/structural-match-no-leak.rs
new file mode 100644
index 000000000..c2ab6a9d1
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/structural-match-no-leak.rs
@@ -0,0 +1,20 @@
+#![feature(type_alias_impl_trait)]
+
+type Bar = impl Send;
+
+// While i32 is structural-match, we do not want to leak this information.
+// (See https://github.com/rust-lang/rust/issues/72156)
+const fn leak_free() -> Bar {
+    7i32
+}
+const LEAK_FREE: Bar = leak_free();
+
+fn leak_free_test() {
+    match LEAK_FREE {
+        LEAK_FREE => (),
+        //~^ `Bar` cannot be used in patterns
+        _ => (),
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/structural-match-no-leak.stderr b/src/test/ui/type-alias-impl-trait/structural-match-no-leak.stderr
new file mode 100644
index 000000000..dbc183f54
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/structural-match-no-leak.stderr
@@ -0,0 +1,8 @@
+error: `Bar` cannot be used in patterns
+  --> $DIR/structural-match-no-leak.rs:14:9
+   |
+LL |         LEAK_FREE => (),
+   |         ^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/structural-match.rs b/src/test/ui/type-alias-impl-trait/structural-match.rs
new file mode 100644
index 000000000..7cc9ccaab
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/structural-match.rs
@@ -0,0 +1,21 @@
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl Send;
+
+// This is not structural-match
+struct A;
+
+const fn value() -> Foo {
+    A
+}
+const VALUE: Foo = value();
+
+fn test() {
+    match VALUE {
+        VALUE => (),
+        //~^ `Foo` cannot be used in patterns
+        _ => (),
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/structural-match.stderr b/src/test/ui/type-alias-impl-trait/structural-match.stderr
new file mode 100644
index 000000000..61287f268
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/structural-match.stderr
@@ -0,0 +1,8 @@
+error: `Foo` cannot be used in patterns
+  --> $DIR/structural-match.rs:15:9
+   |
+LL |         VALUE => (),
+   |         ^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-assoc-dyn.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-assoc-dyn.rs
new file mode 100644
index 000000000..f6a830296
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-assoc-dyn.rs
@@ -0,0 +1,12 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+type Foo = Box<dyn Iterator<Item = impl Send>>;
+
+fn make_foo() -> Foo {
+    Box::new(vec![1, 2, 3].into_iter())
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-assoc-impl-trait.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-assoc-impl-trait.rs
new file mode 100644
index 000000000..fddecfcac
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-assoc-impl-trait.rs
@@ -0,0 +1,19 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+type Foo = impl Iterator<Item = impl Send>;
+
+fn make_foo() -> Foo {
+    vec![1, 2].into_iter()
+}
+
+type Bar = impl Send;
+type Baz = impl Iterator<Item = Bar>;
+
+fn make_baz() -> Baz {
+    vec!["1", "2"].into_iter()
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-const.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-const.rs
new file mode 100644
index 000000000..5630e036b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-const.rs
@@ -0,0 +1,11 @@
+#![feature(type_alias_impl_trait)]
+// check-pass
+// Ensures that `const` items can constrain an opaque `impl Trait`.
+
+use std::fmt::Debug;
+
+pub type Foo = impl Debug;
+
+const _FOO: Foo = 5;
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-fn-type.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-fn-type.rs
new file mode 100644
index 000000000..857066c78
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-fn-type.rs
@@ -0,0 +1,13 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+// FIXME: this is ruled out for now but should work
+
+type Foo = fn() -> impl Send;
+//~^ ERROR: `impl Trait` only allowed in function and inherent method return types
+
+fn make_foo() -> Foo {
+    || 15
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-fn-type.stderr b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-fn-type.stderr
new file mode 100644
index 000000000..a31cf1a51
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-fn-type.stderr
@@ -0,0 +1,9 @@
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return
+  --> $DIR/type-alias-impl-trait-fn-type.rs:6:20
+   |
+LL | type Foo = fn() -> impl Send;
+   |                    ^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0562`.
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-fns.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-fns.rs
new file mode 100644
index 000000000..07c891f06
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-fns.rs
@@ -0,0 +1,26 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+// Regression test for issue #61863
+
+pub trait MyTrait {}
+
+#[derive(Debug)]
+pub struct MyStruct {
+    v: u64,
+}
+
+impl MyTrait for MyStruct {}
+
+pub fn bla() -> TE {
+    return MyStruct { v: 1 };
+}
+
+pub fn bla2() -> TE {
+    bla()
+}
+
+type TE = impl MyTrait;
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-sized.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-sized.rs
new file mode 100644
index 000000000..c5e8068e5
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-sized.rs
@@ -0,0 +1,25 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+type A = impl Sized;
+fn f1() -> A {
+    0
+}
+
+type B = impl ?Sized;
+fn f2() -> &'static B {
+    &[0]
+}
+
+type C = impl ?Sized + 'static;
+fn f3() -> &'static C {
+    &[0]
+}
+
+type D = impl ?Sized;
+fn f4() -> &'static D {
+    &1
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-struct.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-struct.rs
new file mode 100644
index 000000000..1a4064055
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-struct.rs
@@ -0,0 +1,12 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+type Foo = Vec<impl Send>;
+
+fn make_foo() -> Foo {
+    vec![true, false]
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-tuple.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-tuple.rs
new file mode 100644
index 000000000..1f2d0e47e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-tuple.rs
@@ -0,0 +1,30 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+pub trait MyTrait {}
+
+impl MyTrait for bool {}
+
+type Foo = impl MyTrait;
+
+struct Blah {
+    my_foo: Foo,
+    my_u8: u8,
+}
+
+impl Blah {
+    fn new() -> Blah {
+        Blah { my_foo: make_foo(), my_u8: 12 }
+    }
+    fn into_inner(self) -> (Foo, u8, Foo) {
+        (self.my_foo, self.my_u8, make_foo())
+    }
+}
+
+fn make_foo() -> Foo {
+    true
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-unconstrained-lifetime.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-unconstrained-lifetime.rs
new file mode 100644
index 000000000..efbf4f1e3
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-unconstrained-lifetime.rs
@@ -0,0 +1,18 @@
+// regression test for #74018
+
+#![feature(type_alias_impl_trait)]
+
+trait Trait {
+    type Associated;
+    fn into(self) -> Self::Associated;
+}
+
+impl<'a, I: Iterator<Item = i32>> Trait for (i32, I) {
+    //~^ ERROR the lifetime parameter `'a` is not constrained
+    type Associated = (i32, impl Iterator<Item = i32>);
+    fn into(self) -> Self::Associated {
+        (0_i32, [0_i32].iter().copied())
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-unconstrained-lifetime.stderr b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-unconstrained-lifetime.stderr
new file mode 100644
index 000000000..8cdce2f8e
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-unconstrained-lifetime.stderr
@@ -0,0 +1,9 @@
+error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/type-alias-impl-trait-unconstrained-lifetime.rs:10:6
+   |
+LL | impl<'a, I: Iterator<Item = i32>> Trait for (i32, I) {
+   |      ^^ unconstrained lifetime parameter
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0207`.
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error.rs
new file mode 100644
index 000000000..e5e7fb677
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error.rs
@@ -0,0 +1,12 @@
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl Fn() -> Foo;
+//~^ ERROR: unconstrained opaque type
+
+fn crash(x: Foo) -> Foo {
+    x
+}
+
+fn main() {
+
+}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error.stderr b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error.stderr
new file mode 100644
index 000000000..a770eeac3
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error.stderr
@@ -0,0 +1,10 @@
+error: unconstrained opaque type
+  --> $DIR/type-alias-impl-trait-with-cycle-error.rs:3:12
+   |
+LL | type Foo = impl Fn() -> Foo;
+   |            ^^^^^^^^^^^^^^^^
+   |
+   = note: `Foo` must be used in combination with a concrete type within the same module
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error2.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error2.rs
new file mode 100644
index 000000000..7c7a1b405
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error2.rs
@@ -0,0 +1,14 @@
+#![feature(type_alias_impl_trait)]
+
+pub trait Bar<T> {
+    type Item;
+}
+
+type Foo = impl Bar<Foo, Item = Foo>;
+//~^ ERROR: unconstrained opaque type
+
+fn crash(x: Foo) -> Foo {
+    x
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error2.stderr b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error2.stderr
new file mode 100644
index 000000000..3f3699ce5
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-cycle-error2.stderr
@@ -0,0 +1,10 @@
+error: unconstrained opaque type
+  --> $DIR/type-alias-impl-trait-with-cycle-error2.rs:7:12
+   |
+LL | type Foo = impl Bar<Foo, Item = Foo>;
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `Foo` must be used in combination with a concrete type within the same module
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-no-traits.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-no-traits.rs
new file mode 100644
index 000000000..8ca279eec
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-no-traits.rs
@@ -0,0 +1,14 @@
+#![feature(type_alias_impl_trait)]
+
+type Foo = impl 'static;
+//~^ ERROR: at least one trait must be specified
+
+fn foo() -> Foo {
+    "foo"
+}
+
+fn bar() -> impl 'static { //~ ERROR: at least one trait must be specified
+    "foo"
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-no-traits.stderr b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-no-traits.stderr
new file mode 100644
index 000000000..3f7acd338
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-no-traits.stderr
@@ -0,0 +1,14 @@
+error: at least one trait must be specified
+  --> $DIR/type-alias-impl-trait-with-no-traits.rs:3:12
+   |
+LL | type Foo = impl 'static;
+   |            ^^^^^^^^^^^^
+
+error: at least one trait must be specified
+  --> $DIR/type-alias-impl-trait-with-no-traits.rs:10:13
+   |
+LL | fn bar() -> impl 'static {
+   |             ^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait.rs
new file mode 100644
index 000000000..70c2ee427
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait.rs
@@ -0,0 +1,79 @@
+// check-pass
+
+#![allow(dead_code)]
+#![allow(unused_assignments)]
+#![allow(unused_variables)]
+#![feature(type_alias_impl_trait)]
+
+fn main() {
+    assert_eq!(foo().to_string(), "foo");
+    assert_eq!(bar1().to_string(), "bar1");
+    assert_eq!(bar2().to_string(), "bar2");
+    let mut x = bar1();
+    x = bar2();
+    assert_eq!(my_iter(42u8).collect::<Vec<u8>>(), vec![42u8]);
+}
+
+// single definition
+type Foo = impl std::fmt::Display;
+
+fn foo() -> Foo {
+    "foo"
+}
+
+// two definitions
+type Bar = impl std::fmt::Display;
+
+fn bar1() -> Bar {
+    "bar1"
+}
+
+fn bar2() -> Bar {
+    "bar2"
+}
+
+type MyIter<T> = impl Iterator<Item = T>;
+
+fn my_iter<T>(t: T) -> MyIter<T> {
+    std::iter::once(t)
+}
+
+fn my_iter2<T>(t: T) -> MyIter<T> {
+    std::iter::once(t)
+}
+
+// param names should not have an effect!
+fn my_iter3<U>(u: U) -> MyIter<U> {
+    std::iter::once(u)
+}
+
+// param position should not have an effect!
+fn my_iter4<U, V>(_: U, v: V) -> MyIter<V> {
+    std::iter::once(v)
+}
+
+// param names should not have an effect!
+type MyOtherIter<T> = impl Iterator<Item = T>;
+
+fn my_other_iter<U>(u: U) -> MyOtherIter<U> {
+    std::iter::once(u)
+}
+
+trait Trait {}
+type GenericBound<'a, T: Trait + 'a> = impl Sized + 'a;
+
+fn generic_bound<'a, T: Trait + 'a>(t: T) -> GenericBound<'a, T> {
+    t
+}
+
+mod pass_through {
+    pub type Passthrough<T: 'static> = impl Sized + 'static;
+
+    fn define_passthrough<T: 'static>(t: T) -> Passthrough<T> {
+        t
+    }
+}
+
+fn use_passthrough(x: pass_through::Passthrough<u32>) -> pass_through::Passthrough<u32> {
+    x
+}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-impl-trait2.rs b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait2.rs
new file mode 100644
index 000000000..67f56bcde
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-impl-trait2.rs
@@ -0,0 +1,84 @@
+// check-pass
+
+#![allow(dead_code)]
+#![allow(unused_assignments)]
+#![allow(unused_variables)]
+#![feature(type_alias_impl_trait)]
+
+fn main() {
+    assert_eq!(foo().to_string(), "foo");
+    assert_eq!(bar1().to_string(), "bar1");
+    assert_eq!(bar2().to_string(), "bar2");
+    let mut x = bar1();
+    x = bar2();
+    assert_eq!(my_iter(42u8).collect::<Vec<u8>>(), vec![42u8]);
+}
+
+use defining_use_scope::*;
+
+mod defining_use_scope {
+    // single definition
+    pub type Foo = impl std::fmt::Display;
+
+    pub fn foo() -> Foo {
+        "foo"
+    }
+
+    // two definitions
+    pub type Bar = impl std::fmt::Display;
+
+    pub fn bar1() -> Bar {
+        "bar1"
+    }
+
+    pub fn bar2() -> Bar {
+        "bar2"
+    }
+
+    pub type MyIter<T> = impl Iterator<Item = T>;
+
+    pub fn my_iter<T>(t: T) -> MyIter<T> {
+        std::iter::once(t)
+    }
+
+    fn my_iter2<T>(t: T) -> MyIter<T> {
+        std::iter::once(t)
+    }
+
+    // param names should not have an effect!
+    fn my_iter3<U>(u: U) -> MyIter<U> {
+        std::iter::once(u)
+    }
+
+    // param position should not have an effect!
+    fn my_iter4<U, V>(_: U, v: V) -> MyIter<V> {
+        std::iter::once(v)
+    }
+
+    // param names should not have an effect!
+    type MyOtherIter<T> = impl Iterator<Item = T>;
+
+    fn my_other_iter<U>(u: U) -> MyOtherIter<U> {
+        std::iter::once(u)
+    }
+
+    trait Trait {}
+    type GenericBound<'a, T: Trait + 'a> = impl Sized + 'a;
+
+    fn generic_bound<'a, T: Trait + 'a>(t: T) -> GenericBound<'a, T> {
+        t
+    }
+
+    mod pass_through {
+        pub type Passthrough<T: 'static> = impl Sized + 'static;
+
+        fn define_passthrough<T: 'static>(t: T) -> Passthrough<T> {
+            t
+        }
+    }
+
+    fn use_passthrough(x: pass_through::Passthrough<u32>) -> pass_through::Passthrough<u32> {
+        x
+    }
+
+}
diff --git a/src/test/ui/type-alias-impl-trait/type-alias-nested-impl-trait.rs b/src/test/ui/type-alias-impl-trait/type-alias-nested-impl-trait.rs
new file mode 100644
index 000000000..fd954801d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type-alias-nested-impl-trait.rs
@@ -0,0 +1,14 @@
+// run-pass
+
+#![feature(type_alias_impl_trait)]
+
+use std::iter::{once, Chain};
+
+type I<A> = Chain<A, impl Iterator<Item = &'static str>>;
+fn test2<A: Iterator<Item = &'static str>>(x: A) -> I<A> {
+    x.chain(once("5"))
+}
+
+fn main() {
+    assert_eq!(vec!["1", "3", "5"], test2(["1", "3"].iter().cloned()).collect::<Vec<_>>());
+}
diff --git a/src/test/ui/type-alias-impl-trait/type_of_a_let.rs b/src/test/ui/type-alias-impl-trait/type_of_a_let.rs
new file mode 100644
index 000000000..4e9d1788b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type_of_a_let.rs
@@ -0,0 +1,22 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+use std::fmt::Debug;
+
+type Foo = impl Debug;
+
+fn foo1() -> u32 {
+    let x: Foo = 22_u32;
+    x
+}
+
+fn foo2() -> u32 {
+    let x: Foo = 22_u32;
+    let y: Foo = x;
+    same_type((x, y)); //~ ERROR use of moved value
+    y //~ ERROR use of moved value
+}
+
+fn same_type<T>(x: (T, T)) {}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/type_of_a_let.stderr b/src/test/ui/type-alias-impl-trait/type_of_a_let.stderr
new file mode 100644
index 000000000..1dabe4586
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/type_of_a_let.stderr
@@ -0,0 +1,23 @@
+error[E0382]: use of moved value: `x`
+  --> $DIR/type_of_a_let.rs:16:16
+   |
+LL |     let x: Foo = 22_u32;
+   |         - move occurs because `x` has type `Foo`, which does not implement the `Copy` trait
+LL |     let y: Foo = x;
+   |                  - value moved here
+LL |     same_type((x, y));
+   |                ^ value used here after move
+
+error[E0382]: use of moved value: `y`
+  --> $DIR/type_of_a_let.rs:17:5
+   |
+LL |     let y: Foo = x;
+   |         - move occurs because `y` has type `Foo`, which does not implement the `Copy` trait
+LL |     same_type((x, y));
+   |                   - value moved here
+LL |     y
+   |     ^ value used here after move
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0382`.
diff --git a/src/test/ui/type-alias-impl-trait/underconstrained_generic.rs b/src/test/ui/type-alias-impl-trait/underconstrained_generic.rs
new file mode 100644
index 000000000..aa537dfc9
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/underconstrained_generic.rs
@@ -0,0 +1,28 @@
+#![feature(type_alias_impl_trait)]
+
+use std::marker::PhantomData;
+
+trait Trait {
+    fn foo<T, U>(t: T) -> U;
+}
+
+trait ProofForConversion<X> {
+    fn convert<T, U>(_: PhantomData<Self>, r: T) -> U;
+}
+
+impl<X: Trait> ProofForConversion<X> for () {
+    fn convert<T, U>(_: PhantomData<Self>, r: T) -> U {
+        X::foo(r)
+    }
+}
+
+type Converter<T> = impl ProofForConversion<T>;
+
+fn _defining_use<T: Trait>() -> Converter<T> {
+    ()
+    //~^ ERROR the trait bound `T: Trait` is not satisfied
+}
+
+
+fn main() {
+}
diff --git a/src/test/ui/type-alias-impl-trait/underconstrained_generic.stderr b/src/test/ui/type-alias-impl-trait/underconstrained_generic.stderr
new file mode 100644
index 000000000..e70916573
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/underconstrained_generic.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the trait bound `T: Trait` is not satisfied
+  --> $DIR/underconstrained_generic.rs:22:5
+   |
+LL |     ()
+   |     ^^ the trait `Trait` is not implemented for `T`
+   |
+note: required because of the requirements on the impl of `ProofForConversion<T>` for `()`
+  --> $DIR/underconstrained_generic.rs:13:16
+   |
+LL | impl<X: Trait> ProofForConversion<X> for () {
+   |                ^^^^^^^^^^^^^^^^^^^^^     ^^
+help: consider restricting type parameter `T`
+   |
+LL | type Converter<T: Trait> = impl ProofForConversion<T>;
+   |                 +++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/underconstrained_lifetime.rs b/src/test/ui/type-alias-impl-trait/underconstrained_lifetime.rs
new file mode 100644
index 000000000..c5b2e8a1c
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/underconstrained_lifetime.rs
@@ -0,0 +1,34 @@
+#![feature(type_alias_impl_trait)]
+
+use std::marker::PhantomData;
+
+trait ProofForConversion<'a, 'b> {
+    fn convert<T: ?Sized>(_: PhantomData<Self>, r: &'a T) -> &'b T;
+}
+
+impl<'a, 'b> ProofForConversion<'a, 'b> for &'b &'a () {
+    fn convert<T: ?Sized>(_: PhantomData<Self>, r: &'a T) -> &'b T {
+        r
+    }
+}
+
+type Converter<'a, 'b> = impl ProofForConversion<'a, 'b>;
+//~^ ERROR reference has a longer lifetime than the data it references
+
+// Even _defining_use with an explicit `'a: 'b` compiles fine, too.
+fn _defining_use<'a, 'b>(x: &'b &'a ()) -> Converter<'a, 'b> {
+    x
+}
+
+fn extend_lifetime<'a, 'b, T: ?Sized>(x: &'a T) -> &'b T {
+    Converter::<'a, 'b>::convert(PhantomData, x)
+}
+
+fn main() {
+    let d;
+    {
+        let x = "Hello World".to_string();
+        d = extend_lifetime(&x);
+    }
+    println!("{}", d);
+}
diff --git a/src/test/ui/type-alias-impl-trait/underconstrained_lifetime.stderr b/src/test/ui/type-alias-impl-trait/underconstrained_lifetime.stderr
new file mode 100644
index 000000000..12d85a49d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/underconstrained_lifetime.stderr
@@ -0,0 +1,20 @@
+error[E0491]: in type `&'b &'a ()`, reference has a longer lifetime than the data it references
+  --> $DIR/underconstrained_lifetime.rs:15:26
+   |
+LL | type Converter<'a, 'b> = impl ProofForConversion<'a, 'b>;
+   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the pointer is valid for the lifetime `'b` as defined here
+  --> $DIR/underconstrained_lifetime.rs:15:20
+   |
+LL | type Converter<'a, 'b> = impl ProofForConversion<'a, 'b>;
+   |                    ^^
+note: but the referenced data is only valid for the lifetime `'a` as defined here
+  --> $DIR/underconstrained_lifetime.rs:15:16
+   |
+LL | type Converter<'a, 'b> = impl ProofForConversion<'a, 'b>;
+   |                ^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0491`.
diff --git a/src/test/ui/type-alias-impl-trait/unused_generic_param.rs b/src/test/ui/type-alias-impl-trait/unused_generic_param.rs
new file mode 100644
index 000000000..ad5e4918c
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/unused_generic_param.rs
@@ -0,0 +1,22 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+fn main() {}
+
+type PartiallyDefined<T> = impl Sized;
+
+fn partially_defined<T: std::fmt::Debug>(_: T) -> PartiallyDefined<T> {
+    4u32
+}
+
+type PartiallyDefined2<T> = impl Sized;
+
+fn partially_defined2<T: std::fmt::Debug>(_: T) -> PartiallyDefined2<T> {
+    4u32
+}
+
+fn partially_defined22<T>(_: T) -> PartiallyDefined2<T> {
+    4u32
+}
diff --git a/src/test/ui/type-alias-impl-trait/weird-return-types.rs b/src/test/ui/type-alias-impl-trait/weird-return-types.rs
new file mode 100644
index 000000000..faad5ee95
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/weird-return-types.rs
@@ -0,0 +1,16 @@
+// edition:2018
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+use std::future::Future;
+use std::fmt::Debug;
+
+type Foo = impl Debug;
+
+fn f() -> impl Future<Output = Foo> {
+    async move { 22_u32 }
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/wf-check-fn-def.rs b/src/test/ui/type-alias-impl-trait/wf-check-fn-def.rs
new file mode 100644
index 000000000..449e9fbd0
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/wf-check-fn-def.rs
@@ -0,0 +1,18 @@
+#![feature(type_alias_impl_trait)]
+
+trait Bar {
+    fn bar(&self);
+}
+
+type FooFn<B> = impl FnOnce(B);
+
+fn foo<B: Bar>() -> FooFn<B> {
+    fn mop<B: Bar>(bar: B) { bar.bar() }
+    mop // NOTE: no function pointer, but function zst item
+    //~^ ERROR the trait bound `B: Bar` is not satisfied
+}
+
+fn main() {
+    let boom: FooFn<u32> = unsafe { core::mem::zeroed() };
+    boom(42);
+}
diff --git a/src/test/ui/type-alias-impl-trait/wf-check-fn-def.stderr b/src/test/ui/type-alias-impl-trait/wf-check-fn-def.stderr
new file mode 100644
index 000000000..e0005489d
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/wf-check-fn-def.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the trait bound `B: Bar` is not satisfied
+  --> $DIR/wf-check-fn-def.rs:11:5
+   |
+LL |     mop // NOTE: no function pointer, but function zst item
+   |     ^^^ the trait `Bar` is not implemented for `B`
+   |
+note: required by a bound in `mop`
+  --> $DIR/wf-check-fn-def.rs:10:15
+   |
+LL |     fn mop<B: Bar>(bar: B) { bar.bar() }
+   |               ^^^ required by this bound in `mop`
+help: consider restricting type parameter `B`
+   |
+LL | type FooFn<B: Bar> = impl FnOnce(B);
+   |             +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/wf-check-fn-ptrs.rs b/src/test/ui/type-alias-impl-trait/wf-check-fn-ptrs.rs
new file mode 100644
index 000000000..3b8470e4a
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/wf-check-fn-ptrs.rs
@@ -0,0 +1,23 @@
+#![feature(type_alias_impl_trait)]
+
+// build-pass
+
+trait Bar {
+    fn bar(&self);
+}
+
+type FooFn<B> = impl FnOnce(B);
+
+fn foo<B: Bar>() -> FooFn<B> {
+    fn mop<B: Bar>(bar: B) { bar.bar() }
+    mop as fn(B)
+    // function pointers don't have any obligations on them,
+    // thus the above compiles. It's obviously unsound to just
+    // procure a `FooFn` from the ether without making sure that
+    // the pointer is actually legal for all `B`
+}
+
+fn main() {
+    let boom: FooFn<u32> = unsafe { core::mem::zeroed() };
+    boom(42);
+}
diff --git a/src/test/ui/type-alias-impl-trait/wf_check_closures.rs b/src/test/ui/type-alias-impl-trait/wf_check_closures.rs
new file mode 100644
index 000000000..2c70696ff
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/wf_check_closures.rs
@@ -0,0 +1,17 @@
+#![feature(type_alias_impl_trait)]
+
+trait Bar {
+    fn bar(&self);
+}
+
+type FooFn<B> = impl FnOnce();
+
+fn foo<B: Bar>(bar: B) -> FooFn<B> {
+    move || { bar.bar() }
+    //~^ ERROR the trait bound `B: Bar` is not satisfied
+}
+
+fn main() {
+    let boom: FooFn<u32> = unsafe { core::mem::zeroed() };
+    boom();
+}
diff --git a/src/test/ui/type-alias-impl-trait/wf_check_closures.stderr b/src/test/ui/type-alias-impl-trait/wf_check_closures.stderr
new file mode 100644
index 000000000..58ae8617b
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/wf_check_closures.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the trait bound `B: Bar` is not satisfied
+  --> $DIR/wf_check_closures.rs:10:5
+   |
+LL |     move || { bar.bar() }
+   |     ^^^^^^^^^^^^^^^^^^^^^ the trait `Bar` is not implemented for `B`
+   |
+note: required by a bound in `foo`
+  --> $DIR/wf_check_closures.rs:9:11
+   |
+LL | fn foo<B: Bar>(bar: B) -> FooFn<B> {
+   |           ^^^ required by this bound in `foo`
+help: consider restricting type parameter `B`
+   |
+LL | type FooFn<B: Bar> = impl FnOnce();
+   |             +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias/issue-14933.rs b/src/test/ui/type-alias/issue-14933.rs
new file mode 100644
index 000000000..bd95332ca
--- /dev/null
+++ b/src/test/ui/type-alias/issue-14933.rs
@@ -0,0 +1,6 @@
+// check-pass
+// pretty-expanded FIXME #23616
+
+pub type BigRat<T = isize> = T;
+
+fn main() {}
diff --git a/src/test/ui/type-alias/issue-62263-self-in-atb.rs b/src/test/ui/type-alias/issue-62263-self-in-atb.rs
new file mode 100644
index 000000000..91522d891
--- /dev/null
+++ b/src/test/ui/type-alias/issue-62263-self-in-atb.rs
@@ -0,0 +1,8 @@
+pub trait Trait {
+    type A;
+}
+
+pub type Alias = dyn Trait<A = Self::A>;
+//~^ ERROR failed to resolve: `Self`
+
+fn main() {}
diff --git a/src/test/ui/type-alias/issue-62263-self-in-atb.stderr b/src/test/ui/type-alias/issue-62263-self-in-atb.stderr
new file mode 100644
index 000000000..c20074dc2
--- /dev/null
+++ b/src/test/ui/type-alias/issue-62263-self-in-atb.stderr
@@ -0,0 +1,9 @@
+error[E0433]: failed to resolve: `Self` is only available in impls, traits, and type definitions
+  --> $DIR/issue-62263-self-in-atb.rs:5:32
+   |
+LL | pub type Alias = dyn Trait<A = Self::A>;
+   |                                ^^^^ `Self` is only available in impls, traits, and type definitions
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0433`.
diff --git a/src/test/ui/type-alias/issue-62305-self-assoc-ty.rs b/src/test/ui/type-alias/issue-62305-self-assoc-ty.rs
new file mode 100644
index 000000000..a4d9a2854
--- /dev/null
+++ b/src/test/ui/type-alias/issue-62305-self-assoc-ty.rs
@@ -0,0 +1,4 @@
+type Alias = Self::Target;
+//~^ ERROR failed to resolve: `Self`
+
+fn main() {}
diff --git a/src/test/ui/type-alias/issue-62305-self-assoc-ty.stderr b/src/test/ui/type-alias/issue-62305-self-assoc-ty.stderr
new file mode 100644
index 000000000..f3da50df9
--- /dev/null
+++ b/src/test/ui/type-alias/issue-62305-self-assoc-ty.stderr
@@ -0,0 +1,9 @@
+error[E0433]: failed to resolve: `Self` is only available in impls, traits, and type definitions
+  --> $DIR/issue-62305-self-assoc-ty.rs:1:14
+   |
+LL | type Alias = Self::Target;
+   |              ^^^^ `Self` is only available in impls, traits, and type definitions
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0433`.
diff --git a/src/test/ui/type-alias/issue-62364-self-ty-arg.rs b/src/test/ui/type-alias/issue-62364-self-ty-arg.rs
new file mode 100644
index 000000000..bebb4a902
--- /dev/null
+++ b/src/test/ui/type-alias/issue-62364-self-ty-arg.rs
@@ -0,0 +1,8 @@
+struct Struct<P1> {
+    field: P1,
+}
+
+type Alias<'a> = Struct<&'a Self>;
+//~^ ERROR cannot find type `Self` in this scope [E0411]
+
+fn main() {}
diff --git a/src/test/ui/type-alias/issue-62364-self-ty-arg.stderr b/src/test/ui/type-alias/issue-62364-self-ty-arg.stderr
new file mode 100644
index 000000000..7e15e42e3
--- /dev/null
+++ b/src/test/ui/type-alias/issue-62364-self-ty-arg.stderr
@@ -0,0 +1,11 @@
+error[E0411]: cannot find type `Self` in this scope
+  --> $DIR/issue-62364-self-ty-arg.rs:5:29
+   |
+LL | type Alias<'a> = Struct<&'a Self>;
+   |      -----                  ^^^^ `Self` is only available in impls, traits, and type definitions
+   |      |
+   |      `Self` not allowed in a type alias
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0411`.
diff --git a/src/test/ui/type-id-higher-rank-2.rs b/src/test/ui/type-id-higher-rank-2.rs
new file mode 100644
index 000000000..5391c849d
--- /dev/null
+++ b/src/test/ui/type-id-higher-rank-2.rs
@@ -0,0 +1,31 @@
+// run-pass
+// Test that we can't ignore lifetimes by going through Any.
+
+use std::any::Any;
+
+struct Foo<'a>(&'a str);
+
+fn good(s: &String) -> Foo { Foo(s) }
+
+fn bad1(s: String) -> Option<&'static str> {
+    let a: Box<dyn Any> = Box::new(good as fn(&String) -> Foo);
+    a.downcast_ref::<fn(&String) -> Foo<'static>>().map(|f| f(&s).0)
+}
+
+trait AsStr<'a, 'b> {
+    fn get(&'a self) -> &'b str;
+}
+
+impl<'a> AsStr<'a, 'a> for String {
+   fn get(&'a self) -> &'a str { self }
+}
+
+fn bad2(s: String) -> Option<&'static str> {
+    let a: Box<dyn Any> = Box::new(Box::new(s) as Box<dyn for<'a> AsStr<'a, 'a>>);
+    a.downcast_ref::<Box<dyn for<'a> AsStr<'a, 'static>>>().map(|x| x.get())
+}
+
+fn main() {
+    assert_eq!(bad1(String::from("foo")), None);
+    assert_eq!(bad2(String::from("bar")), None);
+}
diff --git a/src/test/ui/type-inference/issue-30225.rs b/src/test/ui/type-inference/issue-30225.rs
new file mode 100644
index 000000000..42315332c
--- /dev/null
+++ b/src/test/ui/type-inference/issue-30225.rs
@@ -0,0 +1,38 @@
+// Regression test for #30225, which was an ICE that would trigger as
+// a result of a poor interaction between trait result caching and
+// type inference. Specifically, at that time, unification could cause
+// unrelated type variables to become instantiated, if subtyping
+// relationships existed. These relationships are now propagated
+// through obligations and hence everything works out fine.
+
+trait Foo<U,V> : Sized {
+    fn foo(self, u: Option<U>, v: Option<V>) {}
+}
+
+struct A;
+struct B;
+
+impl Foo<A, B> for () {}      // impl A
+impl Foo<u32, u32> for u32 {} // impl B, creating ambiguity
+
+fn toxic() {
+    // cache the resolution <() as Foo<$0,$1>> = impl A
+    let u = None;
+    let v = None;
+    Foo::foo((), u, v);
+}
+
+fn bomb() {
+    let mut u = None; // type is Option<$0>
+    let mut v = None; // type is Option<$1>
+    let mut x = None; // type is Option<$2>
+
+    Foo::foo(x.unwrap(),u,v); // register <$2 as Foo<$0, $1>>
+    u = v; // mark $0 and $1 in a subtype relationship
+    //~^ ERROR mismatched types
+    x = Some(()); // set $2 = (), allowing impl selection
+                  // to proceed for <() as Foo<$0, $1>> = impl A.
+                  // kaboom, this *used* to trigge an ICE
+}
+
+fn main() {}
diff --git a/src/test/ui/type-inference/issue-30225.stderr b/src/test/ui/type-inference/issue-30225.stderr
new file mode 100644
index 000000000..ccd05fa6b
--- /dev/null
+++ b/src/test/ui/type-inference/issue-30225.stderr
@@ -0,0 +1,9 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-30225.rs:31:9
+   |
+LL |     u = v; // mark $0 and $1 in a subtype relationship
+   |         ^ expected struct `A`, found struct `B`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type-inference/or_else-multiple-type-params.rs b/src/test/ui/type-inference/or_else-multiple-type-params.rs
new file mode 100644
index 000000000..b15de2a45
--- /dev/null
+++ b/src/test/ui/type-inference/or_else-multiple-type-params.rs
@@ -0,0 +1,10 @@
+use std::process::{Command, Stdio};
+
+fn main() {
+    let process = Command::new("wc")
+        .stdout(Stdio::piped())
+        .spawn()
+        .or_else(|err| { //~ ERROR type annotations needed
+            panic!("oh no: {:?}", err);
+        }).unwrap();
+}
diff --git a/src/test/ui/type-inference/or_else-multiple-type-params.stderr b/src/test/ui/type-inference/or_else-multiple-type-params.stderr
new file mode 100644
index 000000000..6ac63a91e
--- /dev/null
+++ b/src/test/ui/type-inference/or_else-multiple-type-params.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed for `Result<Child, F>`
+  --> $DIR/or_else-multiple-type-params.rs:7:18
+   |
+LL |         .or_else(|err| {
+   |                  ^^^^^
+   |
+help: try giving this closure an explicit return type
+   |
+LL |         .or_else(|err| -> Result<Child, F> {
+   |                        +++++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type-inference/sort_by_key.rs b/src/test/ui/type-inference/sort_by_key.rs
new file mode 100644
index 000000000..afc4d90b8
--- /dev/null
+++ b/src/test/ui/type-inference/sort_by_key.rs
@@ -0,0 +1,5 @@
+fn main() {
+    let mut lst: [([i32; 10], bool); 10] = [([0; 10], false); 10];
+    lst.sort_by_key(|&(v, _)| v.iter().sum()); //~ ERROR type annotations needed
+    println!("{:?}", lst);
+}
diff --git a/src/test/ui/type-inference/sort_by_key.stderr b/src/test/ui/type-inference/sort_by_key.stderr
new file mode 100644
index 000000000..0a48d5756
--- /dev/null
+++ b/src/test/ui/type-inference/sort_by_key.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed
+  --> $DIR/sort_by_key.rs:3:40
+   |
+LL |     lst.sort_by_key(|&(v, _)| v.iter().sum());
+   |                                        ^^^ cannot infer type of the type parameter `S` declared on the associated function `sum`
+   |
+help: consider specifying the generic argument
+   |
+LL |     lst.sort_by_key(|&(v, _)| v.iter().sum::<S>());
+   |                                           +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type-inference/unbounded-associated-type.rs b/src/test/ui/type-inference/unbounded-associated-type.rs
new file mode 100644
index 000000000..0167e9436
--- /dev/null
+++ b/src/test/ui/type-inference/unbounded-associated-type.rs
@@ -0,0 +1,16 @@
+trait T {
+    type A;
+    fn foo(&self) -> Self::A {
+        panic!()
+    }
+}
+
+struct S<X>(std::marker::PhantomData<X>);
+
+impl<X> T for S<X> {
+   type A = X;
+}
+
+fn main() {
+    S(std::marker::PhantomData).foo(); //~ ERROR type annotations needed
+}
diff --git a/src/test/ui/type-inference/unbounded-associated-type.stderr b/src/test/ui/type-inference/unbounded-associated-type.stderr
new file mode 100644
index 000000000..e0fecc72f
--- /dev/null
+++ b/src/test/ui/type-inference/unbounded-associated-type.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed
+  --> $DIR/unbounded-associated-type.rs:15:7
+   |
+LL |     S(std::marker::PhantomData).foo();
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the struct `PhantomData`
+   |
+help: consider specifying the generic argument
+   |
+LL |     S(std::marker::PhantomData::<T>).foo();
+   |                               +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type-inference/unbounded-type-param-in-fn-with-assoc-type.rs b/src/test/ui/type-inference/unbounded-type-param-in-fn-with-assoc-type.rs
new file mode 100644
index 000000000..81d054b3a
--- /dev/null
+++ b/src/test/ui/type-inference/unbounded-type-param-in-fn-with-assoc-type.rs
@@ -0,0 +1,9 @@
+#[allow(invalid_type_param_default)]
+
+fn foo<T, U = u64>() -> (T, U) {
+    panic!()
+}
+
+fn main() {
+    foo(); //~ ERROR type annotations needed
+}
diff --git a/src/test/ui/type-inference/unbounded-type-param-in-fn-with-assoc-type.stderr b/src/test/ui/type-inference/unbounded-type-param-in-fn-with-assoc-type.stderr
new file mode 100644
index 000000000..209abfe5c
--- /dev/null
+++ b/src/test/ui/type-inference/unbounded-type-param-in-fn-with-assoc-type.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed
+  --> $DIR/unbounded-type-param-in-fn-with-assoc-type.rs:8:5
+   |
+LL |     foo();
+   |     ^^^ cannot infer type of the type parameter `T` declared on the function `foo`
+   |
+help: consider specifying the generic arguments
+   |
+LL |     foo::<T, U>();
+   |        ++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type-inference/unbounded-type-param-in-fn.rs b/src/test/ui/type-inference/unbounded-type-param-in-fn.rs
new file mode 100644
index 000000000..1f336ed59
--- /dev/null
+++ b/src/test/ui/type-inference/unbounded-type-param-in-fn.rs
@@ -0,0 +1,7 @@
+fn foo<T>() -> T {
+    panic!()
+}
+
+fn main() {
+    foo(); //~ ERROR type annotations needed
+}
diff --git a/src/test/ui/type-inference/unbounded-type-param-in-fn.stderr b/src/test/ui/type-inference/unbounded-type-param-in-fn.stderr
new file mode 100644
index 000000000..d92892eeb
--- /dev/null
+++ b/src/test/ui/type-inference/unbounded-type-param-in-fn.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed
+  --> $DIR/unbounded-type-param-in-fn.rs:6:5
+   |
+LL |     foo();
+   |     ^^^ cannot infer type of the type parameter `T` declared on the function `foo`
+   |
+help: consider specifying the generic argument
+   |
+LL |     foo::<T>();
+   |        +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type-namespace.rs b/src/test/ui/type-namespace.rs
new file mode 100644
index 000000000..3cc0bc447
--- /dev/null
+++ b/src/test/ui/type-namespace.rs
@@ -0,0 +1,7 @@
+// run-pass
+
+struct A { a: isize }
+
+fn a(a: A) -> isize { return a.a; }
+
+pub fn main() { let x: A = A {a: 1}; assert_eq!(a(x), 1); }
diff --git a/src/test/ui/type-param-constraints.rs b/src/test/ui/type-param-constraints.rs
new file mode 100644
index 000000000..3d87a089f
--- /dev/null
+++ b/src/test/ui/type-param-constraints.rs
@@ -0,0 +1,37 @@
+// run-pass
+
+#![allow(non_camel_case_types)]
+#![allow(dead_code)]
+// pretty-expanded FIXME #23616
+
+fn p_foo<T>(_pinned: T) { }
+fn s_foo<T>(_shared: T) { }
+fn u_foo<T:Send>(_unique: T) { }
+
+struct r {
+  i: isize,
+}
+
+impl Drop for r {
+    fn drop(&mut self) {}
+}
+
+fn r(i:isize) -> r {
+    r {
+        i: i
+    }
+}
+
+pub fn main() {
+    p_foo(r(10));
+
+    p_foo::<Box<_>>(Box::new(r(10)));
+    p_foo::<Box<_>>(Box::new(10));
+    p_foo(10);
+
+    s_foo::<Box<_>>(Box::new(10));
+    s_foo(10);
+
+    u_foo::<Box<_>>(Box::new(10));
+    u_foo(10);
+}
diff --git a/src/test/ui/type-param.rs b/src/test/ui/type-param.rs
new file mode 100644
index 000000000..ca2f24d37
--- /dev/null
+++ b/src/test/ui/type-param.rs
@@ -0,0 +1,11 @@
+// run-pass
+
+#![allow(non_camel_case_types)]
+#![allow(dead_code)]
+
+
+// pretty-expanded FIXME #23616
+
+type lteq<T> = extern "C" fn(T) -> bool;
+
+pub fn main() { }
diff --git a/src/test/ui/type-ptr.rs b/src/test/ui/type-ptr.rs
new file mode 100644
index 000000000..7c2438d38
--- /dev/null
+++ b/src/test/ui/type-ptr.rs
@@ -0,0 +1,10 @@
+// run-pass
+
+#![allow(dead_code)]
+// pretty-expanded FIXME #23616
+
+fn f(a: *const isize) -> *const isize { return a; }
+
+fn g(a: *const isize) -> *const isize { let b = f(a); return b; }
+
+pub fn main() { return; }
diff --git a/src/test/ui/type-use-i1-versus-i8.rs b/src/test/ui/type-use-i1-versus-i8.rs
new file mode 100644
index 000000000..7315cd2fe
--- /dev/null
+++ b/src/test/ui/type-use-i1-versus-i8.rs
@@ -0,0 +1,12 @@
+// run-pass
+// pretty-expanded FIXME #23616
+
+use std::ptr;
+
+pub fn main() {
+    unsafe {
+        let mut x: bool = false;
+        // this line breaks it
+        ptr::write(&mut x, false);
+    }
+}
diff --git a/src/test/ui/type/ascription/issue-34255-1.rs b/src/test/ui/type/ascription/issue-34255-1.rs
new file mode 100644
index 000000000..44b47cc4e
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-34255-1.rs
@@ -0,0 +1,15 @@
+struct Reactor {
+    input_cells: Vec<usize>,
+}
+
+impl Reactor {
+    pub fn new() -> Self {
+        input_cells: Vec::new()
+        //~^ ERROR cannot find value `input_cells` in this scope
+        //~| ERROR parenthesized type parameters may only be used with a `Fn` trait
+        //~| ERROR missing generics for struct `Vec`
+    }
+}
+
+// This case isn't currently being handled gracefully, including for completeness.
+fn main() {}
diff --git a/src/test/ui/type/ascription/issue-34255-1.stderr b/src/test/ui/type/ascription/issue-34255-1.stderr
new file mode 100644
index 000000000..6819d14bb
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-34255-1.stderr
@@ -0,0 +1,41 @@
+error[E0425]: cannot find value `input_cells` in this scope
+  --> $DIR/issue-34255-1.rs:7:9
+   |
+LL |         input_cells: Vec::new()
+   |         ^^^^^^^^^^^ a field by this name exists in `Self`
+   |
+help: you might have meant to write a `struct` literal
+   |
+LL ~     pub fn new() -> Self { SomeStruct {
+LL |         input_cells: Vec::new()
+ ...
+LL |
+LL ~     }}
+   |
+
+error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
+  --> $DIR/issue-34255-1.rs:7:27
+   |
+LL |         input_cells: Vec::new()
+   |                           ^^^^^ only `Fn` traits may use parentheses
+
+error[E0107]: missing generics for struct `Vec`
+  --> $DIR/issue-34255-1.rs:7:22
+   |
+LL |         input_cells: Vec::new()
+   |                      ^^^ expected at least 1 generic argument
+   |
+note: struct defined here, with at least 1 generic parameter: `T`
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+   |
+LL | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
+   |            ^^^ -
+help: add missing generic argument
+   |
+LL |         input_cells: Vec<T>::new()
+   |                      ~~~~~~
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0107, E0214, E0425.
+For more information about an error, try `rustc --explain E0107`.
diff --git a/src/test/ui/type/ascription/issue-47666.fixed b/src/test/ui/type/ascription/issue-47666.fixed
new file mode 100644
index 000000000..c4db74755
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-47666.fixed
@@ -0,0 +1,4 @@
+// run-rustfix
+fn main() {
+    let _ = Option::Some(vec![0, 1]); //~ ERROR expected type, found
+}
diff --git a/src/test/ui/type/ascription/issue-47666.rs b/src/test/ui/type/ascription/issue-47666.rs
new file mode 100644
index 000000000..c67202e21
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-47666.rs
@@ -0,0 +1,4 @@
+// run-rustfix
+fn main() {
+    let _ = Option:Some(vec![0, 1]); //~ ERROR expected type, found
+}
diff --git a/src/test/ui/type/ascription/issue-47666.stderr b/src/test/ui/type/ascription/issue-47666.stderr
new file mode 100644
index 000000000..0f90fce3a
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-47666.stderr
@@ -0,0 +1,16 @@
+error: expected type, found `<[_]>::into_vec(#[rustc_box] ::alloc::boxed::Box::new([0, 1]))`
+  --> $DIR/issue-47666.rs:3:25
+   |
+LL |     let _ = Option:Some(vec![0, 1]);
+   |                   -     ^^^^^^^^^^
+   |                   |     |
+   |                   |     expected type
+   |                   |     in this macro invocation
+   |                   |     this macro call doesn't expand to a type
+   |                   help: maybe write a path separator here: `::`
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+   = note: this error originates in the macro `$crate::__rust_force_expr` which comes from the expansion of the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type/ascription/issue-54516.fixed b/src/test/ui/type/ascription/issue-54516.fixed
new file mode 100644
index 000000000..f78268894
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-54516.fixed
@@ -0,0 +1,7 @@
+// run-rustfix
+use std::collections::BTreeMap;
+
+fn main() {
+    println!("{}", std::mem::size_of::<BTreeMap<u32, u32>>());
+    //~^ ERROR type ascription cannot be followed by a function call
+}
diff --git a/src/test/ui/type/ascription/issue-54516.rs b/src/test/ui/type/ascription/issue-54516.rs
new file mode 100644
index 000000000..1f34e6943
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-54516.rs
@@ -0,0 +1,7 @@
+// run-rustfix
+use std::collections::BTreeMap;
+
+fn main() {
+    println!("{}", std::mem:size_of::<BTreeMap<u32, u32>>());
+    //~^ ERROR type ascription cannot be followed by a function call
+}
diff --git a/src/test/ui/type/ascription/issue-54516.stderr b/src/test/ui/type/ascription/issue-54516.stderr
new file mode 100644
index 000000000..1ab9093e5
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-54516.stderr
@@ -0,0 +1,12 @@
+error: type ascription cannot be followed by a function call
+  --> $DIR/issue-54516.rs:5:20
+   |
+LL |     println!("{}", std::mem:size_of::<BTreeMap<u32, u32>>());
+   |                    ^^^^^^^^-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                            |
+   |                            help: maybe write a path separator here: `::`
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type/ascription/issue-60933.fixed b/src/test/ui/type/ascription/issue-60933.fixed
new file mode 100644
index 000000000..3e8be3875
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-60933.fixed
@@ -0,0 +1,5 @@
+// run-rustfix
+fn main() {
+    let _: usize = std::mem::size_of::<u32>();
+    //~^ ERROR type ascription cannot be followed by a function call
+}
diff --git a/src/test/ui/type/ascription/issue-60933.rs b/src/test/ui/type/ascription/issue-60933.rs
new file mode 100644
index 000000000..2a4ad7bdc
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-60933.rs
@@ -0,0 +1,5 @@
+// run-rustfix
+fn main() {
+    let _: usize = std::mem:size_of::<u32>();
+    //~^ ERROR type ascription cannot be followed by a function call
+}
diff --git a/src/test/ui/type/ascription/issue-60933.stderr b/src/test/ui/type/ascription/issue-60933.stderr
new file mode 100644
index 000000000..0b7f8edf6
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-60933.stderr
@@ -0,0 +1,12 @@
+error: type ascription cannot be followed by a function call
+  --> $DIR/issue-60933.rs:3:20
+   |
+LL |     let _: usize = std::mem:size_of::<u32>();
+   |                    ^^^^^^^^-^^^^^^^^^^^^^^
+   |                            |
+   |                            help: maybe write a path separator here: `::`
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type/auxiliary/crate_a1.rs b/src/test/ui/type/auxiliary/crate_a1.rs
new file mode 100644
index 000000000..e2e185005
--- /dev/null
+++ b/src/test/ui/type/auxiliary/crate_a1.rs
@@ -0,0 +1,11 @@
+pub struct Foo;
+
+pub trait Bar{}
+
+pub fn bar() -> Box<Bar> {
+    unimplemented!()
+}
+
+
+pub fn try_foo(x: Foo){}
+pub fn try_bar(x: Box<Bar>){}
diff --git a/src/test/ui/type/auxiliary/crate_a2.rs b/src/test/ui/type/auxiliary/crate_a2.rs
new file mode 100644
index 000000000..d16a4ac10
--- /dev/null
+++ b/src/test/ui/type/auxiliary/crate_a2.rs
@@ -0,0 +1,7 @@
+pub struct Foo;
+
+pub trait Bar{}
+
+pub fn bar() -> Box<Bar> {
+    unimplemented!()
+}
diff --git a/src/test/ui/type/issue-67690-type-alias-bound-diagnostic-crash.rs b/src/test/ui/type/issue-67690-type-alias-bound-diagnostic-crash.rs
new file mode 100644
index 000000000..68aadcf60
--- /dev/null
+++ b/src/test/ui/type/issue-67690-type-alias-bound-diagnostic-crash.rs
@@ -0,0 +1,8 @@
+// Regression test for issue #67690
+// Rustc endless loop out-of-memory and consequent SIGKILL in generic new type
+
+// check-pass
+pub type T<P: Send + Send + Send> = P;
+//~^ WARN bounds on generic parameters are not enforced in type aliases
+
+fn main() {}
diff --git a/src/test/ui/type/issue-67690-type-alias-bound-diagnostic-crash.stderr b/src/test/ui/type/issue-67690-type-alias-bound-diagnostic-crash.stderr
new file mode 100644
index 000000000..125ffbbb4
--- /dev/null
+++ b/src/test/ui/type/issue-67690-type-alias-bound-diagnostic-crash.stderr
@@ -0,0 +1,15 @@
+warning: bounds on generic parameters are not enforced in type aliases
+  --> $DIR/issue-67690-type-alias-bound-diagnostic-crash.rs:5:15
+   |
+LL | pub type T<P: Send + Send + Send> = P;
+   |               ^^^^   ^^^^   ^^^^
+   |
+   = note: `#[warn(type_alias_bounds)]` on by default
+help: the bound will not be checked when the type alias is used, and should be removed
+   |
+LL - pub type T<P: Send + Send + Send> = P;
+LL + pub type T<P> = P;
+   |
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/type/issue-91268.rs b/src/test/ui/type/issue-91268.rs
new file mode 100644
index 000000000..f1e16bc7b
--- /dev/null
+++ b/src/test/ui/type/issue-91268.rs
@@ -0,0 +1,9 @@
+// error-pattern: this file contains an unclosed delimiter
+// error-pattern: cannot find type `ţ` in this scope
+// error-pattern: parenthesized type parameters may only be used with a `Fn` trait
+// error-pattern: type arguments are not allowed on builtin type `u8`
+// error-pattern: mismatched types
+// ignore-tidy-trailing-newlines
+// `ţ` must be the last character in this file, it cannot be followed by a newline
+fn main() {
+    0: u8(ţ
\ No newline at end of file
diff --git a/src/test/ui/type/issue-91268.stderr b/src/test/ui/type/issue-91268.stderr
new file mode 100644
index 000000000..6c9ee9945
--- /dev/null
+++ b/src/test/ui/type/issue-91268.stderr
@@ -0,0 +1,63 @@
+error: this file contains an unclosed delimiter
+  --> $DIR/issue-91268.rs:9:12
+   |
+LL | fn main() {
+   |           - unclosed delimiter
+LL |     0: u8(ţ
+   |          - ^
+   |          |
+   |          unclosed delimiter
+
+error: this file contains an unclosed delimiter
+  --> $DIR/issue-91268.rs:9:12
+   |
+LL | fn main() {
+   |           - unclosed delimiter
+LL |     0: u8(ţ
+   |          - ^
+   |          |
+   |          unclosed delimiter
+
+error[E0412]: cannot find type `ţ` in this scope
+  --> $DIR/issue-91268.rs:9:11
+   |
+LL |     0: u8(ţ
+   |           ^ expecting a type here because of type ascription
+
+error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
+  --> $DIR/issue-91268.rs:9:8
+   |
+LL |     0: u8(ţ
+   |        ^^^^ only `Fn` traits may use parentheses
+   |
+help: use angle brackets instead
+   |
+LL |     0: u8<ţ>
+   |          ~ +
+
+error[E0109]: type arguments are not allowed on builtin type `u8`
+  --> $DIR/issue-91268.rs:9:11
+   |
+LL |     0: u8(ţ
+   |        -- ^ type argument not allowed
+   |        |
+   |        not allowed on builtin type `u8`
+   |
+help: primitive type `u8` doesn't have generic parameters
+   |
+LL -     0: u8(ţ
+LL +     0: u8
+   |
+
+error[E0308]: mismatched types
+  --> $DIR/issue-91268.rs:9:5
+   |
+LL | fn main() {
+   |           - expected `()` because of default return type
+LL |     0: u8(ţ
+   |     ^^^^^^^ expected `()`, found `u8`
+
+error: aborting due to 6 previous errors
+
+Some errors have detailed explanations: E0109, E0214, E0308, E0412.
+For more information about an error, try `rustc --explain E0109`.
diff --git a/src/test/ui/type/missing-let-in-binding.fixed b/src/test/ui/type/missing-let-in-binding.fixed
new file mode 100644
index 000000000..d17876889
--- /dev/null
+++ b/src/test/ui/type/missing-let-in-binding.fixed
@@ -0,0 +1,5 @@
+// run-rustfix
+fn main() {
+    let mut _foo: i32 = 1;
+    let _foo: i32 = 4; //~ ERROR type ascription is experimental
+}
diff --git a/src/test/ui/type/missing-let-in-binding.rs b/src/test/ui/type/missing-let-in-binding.rs
new file mode 100644
index 000000000..ca42f2e6e
--- /dev/null
+++ b/src/test/ui/type/missing-let-in-binding.rs
@@ -0,0 +1,5 @@
+// run-rustfix
+fn main() {
+    let mut _foo: i32 = 1;
+    _foo: i32 = 4; //~ ERROR type ascription is experimental
+}
diff --git a/src/test/ui/type/missing-let-in-binding.stderr b/src/test/ui/type/missing-let-in-binding.stderr
new file mode 100644
index 000000000..12759c509
--- /dev/null
+++ b/src/test/ui/type/missing-let-in-binding.stderr
@@ -0,0 +1,16 @@
+error[E0658]: type ascription is experimental
+  --> $DIR/missing-let-in-binding.rs:4:5
+   |
+LL |     _foo: i32 = 4;
+   |     ^^^^^^^^^
+   |
+   = note: see issue #23416 <https://github.com/rust-lang/rust/issues/23416> for more information
+   = help: add `#![feature(type_ascription)]` to the crate attributes to enable
+help: you might have meant to introduce a new binding
+   |
+LL |     let _foo: i32 = 4;
+   |     +++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/type/type-alias-bounds.rs b/src/test/ui/type/type-alias-bounds.rs
new file mode 100644
index 000000000..65b79650d
--- /dev/null
+++ b/src/test/ui/type/type-alias-bounds.rs
@@ -0,0 +1,59 @@
+// Test `ignored_generic_bounds` lint warning about bounds in type aliases.
+
+// check-pass
+#![allow(dead_code)]
+
+use std::rc::Rc;
+
+type SVec<T: Send + Send> = Vec<T>;
+//~^ WARN bounds on generic parameters are not enforced in type aliases [type_alias_bounds]
+type S2Vec<T> where T: Send = Vec<T>;
+//~^ WARN where clauses are not enforced in type aliases [type_alias_bounds]
+type VVec<'b, 'a: 'b + 'b> = (&'b u32, Vec<&'a i32>);
+//~^ WARN bounds on generic parameters are not enforced in type aliases [type_alias_bounds]
+type WVec<'b, T: 'b + 'b> = (&'b u32, Vec<T>);
+//~^ WARN bounds on generic parameters are not enforced in type aliases [type_alias_bounds]
+type W2Vec<'b, T> where T: 'b, T: 'b = (&'b u32, Vec<T>);
+//~^ WARN where clauses are not enforced in type aliases [type_alias_bounds]
+
+static STATIC: u32 = 0;
+
+fn foo<'a>(y: &'a i32) {
+    // If any of the bounds above would matter, the code below would be rejected.
+    // This can be seen when replacing the type aliases above by newtype structs.
+    // (The type aliases have no unused parameters to make that a valid transformation.)
+    let mut x: SVec<_> = Vec::new();
+    x.push(Rc::new(42)); // is not send
+
+    let mut x: S2Vec<_> = Vec::new();
+    x.push(Rc::new(42)); // is not `Send`
+
+    let mut x: VVec<'static, 'a> = (&STATIC, Vec::new());
+    x.1.push(y); // `'a: 'static` does not hold
+
+    let mut x: WVec<'static, &'a i32> = (&STATIC, Vec::new());
+    x.1.push(y); // `&'a i32: 'static` does not hold
+
+    let mut x: W2Vec<'static, &'a i32> = (&STATIC, Vec::new());
+    x.1.push(y); // `&'a i32: 'static` does not hold
+}
+
+// Bounds are not checked either; i.e., the definition is not necessarily well-formed.
+struct Sendable<T: Send>(T);
+type MySendable<T> = Sendable<T>; // no error here!
+
+// However, bounds *are* taken into account when accessing associated types
+trait Bound { type Assoc; }
+type T1<U: Bound> = U::Assoc; //~ WARN not enforced in type aliases
+type T2<U> where U: Bound = U::Assoc;  //~ WARN not enforced in type aliases
+
+// This errors:
+// `type T3<U> = U::Assoc;`
+// Do this instead:
+type T4<U> = <U as Bound>::Assoc;
+
+// Make sure the help about associatd types is not shown incorrectly
+type T5<U: Bound> = <U as Bound>::Assoc;  //~ WARN not enforced in type aliases
+type T6<U: Bound> = ::std::vec::Vec<U>;  //~ WARN not enforced in type aliases
+
+fn main() {}
diff --git a/src/test/ui/type/type-alias-bounds.stderr b/src/test/ui/type/type-alias-bounds.stderr
new file mode 100644
index 000000000..92e573393
--- /dev/null
+++ b/src/test/ui/type/type-alias-bounds.stderr
@@ -0,0 +1,121 @@
+warning: bounds on generic parameters are not enforced in type aliases
+  --> $DIR/type-alias-bounds.rs:8:14
+   |
+LL | type SVec<T: Send + Send> = Vec<T>;
+   |              ^^^^   ^^^^
+   |
+   = note: `#[warn(type_alias_bounds)]` on by default
+help: the bound will not be checked when the type alias is used, and should be removed
+   |
+LL - type SVec<T: Send + Send> = Vec<T>;
+LL + type SVec<T> = Vec<T>;
+   |
+
+warning: where clauses are not enforced in type aliases
+  --> $DIR/type-alias-bounds.rs:10:21
+   |
+LL | type S2Vec<T> where T: Send = Vec<T>;
+   |                     ^^^^^^^
+   |
+help: the clause will not be checked when the type alias is used, and should be removed
+   |
+LL - type S2Vec<T> where T: Send = Vec<T>;
+LL + type S2Vec<T>  = Vec<T>;
+   |
+
+warning: bounds on generic parameters are not enforced in type aliases
+  --> $DIR/type-alias-bounds.rs:12:19
+   |
+LL | type VVec<'b, 'a: 'b + 'b> = (&'b u32, Vec<&'a i32>);
+   |                   ^^   ^^
+   |
+help: the bound will not be checked when the type alias is used, and should be removed
+   |
+LL - type VVec<'b, 'a: 'b + 'b> = (&'b u32, Vec<&'a i32>);
+LL + type VVec<'b, 'a> = (&'b u32, Vec<&'a i32>);
+   |
+
+warning: bounds on generic parameters are not enforced in type aliases
+  --> $DIR/type-alias-bounds.rs:14:18
+   |
+LL | type WVec<'b, T: 'b + 'b> = (&'b u32, Vec<T>);
+   |                  ^^   ^^
+   |
+help: the bound will not be checked when the type alias is used, and should be removed
+   |
+LL - type WVec<'b, T: 'b + 'b> = (&'b u32, Vec<T>);
+LL + type WVec<'b, T> = (&'b u32, Vec<T>);
+   |
+
+warning: where clauses are not enforced in type aliases
+  --> $DIR/type-alias-bounds.rs:16:25
+   |
+LL | type W2Vec<'b, T> where T: 'b, T: 'b = (&'b u32, Vec<T>);
+   |                         ^^^^^  ^^^^^
+   |
+help: the clause will not be checked when the type alias is used, and should be removed
+   |
+LL - type W2Vec<'b, T> where T: 'b, T: 'b = (&'b u32, Vec<T>);
+LL + type W2Vec<'b, T>  = (&'b u32, Vec<T>);
+   |
+
+warning: bounds on generic parameters are not enforced in type aliases
+  --> $DIR/type-alias-bounds.rs:47:12
+   |
+LL | type T1<U: Bound> = U::Assoc;
+   |            ^^^^^
+   |
+help: use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to associated types in type aliases
+  --> $DIR/type-alias-bounds.rs:47:21
+   |
+LL | type T1<U: Bound> = U::Assoc;
+   |                     ^^^^^^^^
+help: the bound will not be checked when the type alias is used, and should be removed
+   |
+LL - type T1<U: Bound> = U::Assoc;
+LL + type T1<U> = U::Assoc;
+   |
+
+warning: where clauses are not enforced in type aliases
+  --> $DIR/type-alias-bounds.rs:48:18
+   |
+LL | type T2<U> where U: Bound = U::Assoc;
+   |                  ^^^^^^^^
+   |
+help: use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to associated types in type aliases
+  --> $DIR/type-alias-bounds.rs:48:29
+   |
+LL | type T2<U> where U: Bound = U::Assoc;
+   |                             ^^^^^^^^
+help: the clause will not be checked when the type alias is used, and should be removed
+   |
+LL - type T2<U> where U: Bound = U::Assoc;
+LL + type T2<U>  = U::Assoc;
+   |
+
+warning: bounds on generic parameters are not enforced in type aliases
+  --> $DIR/type-alias-bounds.rs:56:12
+   |
+LL | type T5<U: Bound> = <U as Bound>::Assoc;
+   |            ^^^^^
+   |
+help: the bound will not be checked when the type alias is used, and should be removed
+   |
+LL - type T5<U: Bound> = <U as Bound>::Assoc;
+LL + type T5<U> = <U as Bound>::Assoc;
+   |
+
+warning: bounds on generic parameters are not enforced in type aliases
+  --> $DIR/type-alias-bounds.rs:57:12
+   |
+LL | type T6<U: Bound> = ::std::vec::Vec<U>;
+   |            ^^^^^
+   |
+help: the bound will not be checked when the type alias is used, and should be removed
+   |
+LL - type T6<U: Bound> = ::std::vec::Vec<U>;
+LL + type T6<U> = ::std::vec::Vec<U>;
+   |
+
+warning: 9 warnings emitted
+
diff --git a/src/test/ui/type/type-annotation-needed.rs b/src/test/ui/type/type-annotation-needed.rs
new file mode 100644
index 000000000..347887f4b
--- /dev/null
+++ b/src/test/ui/type/type-annotation-needed.rs
@@ -0,0 +1,10 @@
+fn foo<T: Into<String>>(x: i32) {}
+//~^ NOTE required by
+//~| NOTE required by
+
+fn main() {
+    foo(42);
+    //~^ ERROR type annotations needed
+    //~| NOTE cannot infer type
+    //~| NOTE cannot satisfy
+}
diff --git a/src/test/ui/type/type-annotation-needed.stderr b/src/test/ui/type/type-annotation-needed.stderr
new file mode 100644
index 000000000..4af4c22f7
--- /dev/null
+++ b/src/test/ui/type/type-annotation-needed.stderr
@@ -0,0 +1,20 @@
+error[E0283]: type annotations needed
+  --> $DIR/type-annotation-needed.rs:6:5
+   |
+LL |     foo(42);
+   |     ^^^ cannot infer type of the type parameter `T` declared on the function `foo`
+   |
+   = note: cannot satisfy `_: Into<String>`
+note: required by a bound in `foo`
+  --> $DIR/type-annotation-needed.rs:1:11
+   |
+LL | fn foo<T: Into<String>>(x: i32) {}
+   |           ^^^^^^^^^^^^ required by this bound in `foo`
+help: consider specifying the type argument in the function call
+   |
+LL |     foo::<T>(42);
+   |        +++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0283`.
diff --git a/src/test/ui/type/type-arg-out-of-scope.rs b/src/test/ui/type/type-arg-out-of-scope.rs
new file mode 100644
index 000000000..02aad0077
--- /dev/null
+++ b/src/test/ui/type/type-arg-out-of-scope.rs
@@ -0,0 +1,5 @@
+// error-pattern:can't use generic parameters from outer function
+fn foo<T>(x: T) {
+    fn bar(f: Box<dyn FnMut(T) -> T>) { }
+}
+fn main() { foo(1); }
diff --git a/src/test/ui/type/type-arg-out-of-scope.stderr b/src/test/ui/type/type-arg-out-of-scope.stderr
new file mode 100644
index 000000000..0b6283fbc
--- /dev/null
+++ b/src/test/ui/type/type-arg-out-of-scope.stderr
@@ -0,0 +1,23 @@
+error[E0401]: can't use generic parameters from outer function
+  --> $DIR/type-arg-out-of-scope.rs:3:29
+   |
+LL | fn foo<T>(x: T) {
+   |        - type parameter from outer function
+LL |     fn bar(f: Box<dyn FnMut(T) -> T>) { }
+   |        ---                  ^ use of generic parameter from outer function
+   |        |
+   |        help: try using a local generic parameter instead: `bar<T>`
+
+error[E0401]: can't use generic parameters from outer function
+  --> $DIR/type-arg-out-of-scope.rs:3:35
+   |
+LL | fn foo<T>(x: T) {
+   |        - type parameter from outer function
+LL |     fn bar(f: Box<dyn FnMut(T) -> T>) { }
+   |        ---                        ^ use of generic parameter from outer function
+   |        |
+   |        help: try using a local generic parameter instead: `bar<T>`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0401`.
diff --git a/src/test/ui/type/type-ascription-instead-of-initializer.rs b/src/test/ui/type/type-ascription-instead-of-initializer.rs
new file mode 100644
index 000000000..9f9b6f06b
--- /dev/null
+++ b/src/test/ui/type/type-ascription-instead-of-initializer.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let x: Vec::with_capacity(10, 20);  //~ ERROR expected type, found `10`
+    //~^ ERROR this function takes 1 argument
+}
diff --git a/src/test/ui/type/type-ascription-instead-of-initializer.stderr b/src/test/ui/type/type-ascription-instead-of-initializer.stderr
new file mode 100644
index 000000000..fcac6c495
--- /dev/null
+++ b/src/test/ui/type/type-ascription-instead-of-initializer.stderr
@@ -0,0 +1,28 @@
+error: expected type, found `10`
+  --> $DIR/type-ascription-instead-of-initializer.rs:2:31
+   |
+LL |     let x: Vec::with_capacity(10, 20);
+   |         --                    ^^ expected type
+   |         ||
+   |         |help: use `=` if you meant to assign
+   |         while parsing the type for `x`
+
+error[E0061]: this function takes 1 argument but 2 arguments were supplied
+  --> $DIR/type-ascription-instead-of-initializer.rs:2:12
+   |
+LL |     let x: Vec::with_capacity(10, 20);
+   |            ^^^^^^^^^^^^^^^^^^     -- argument of type `{integer}` unexpected
+   |
+note: associated function defined here
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+   |
+LL |     pub fn with_capacity(capacity: usize) -> Self {
+   |            ^^^^^^^^^^^^^
+help: remove the extra argument
+   |
+LL |     let x: Vec::with_capacity(10);
+   |            ~~~~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0061`.
diff --git a/src/test/ui/type/type-ascription-instead-of-statement-end.rs b/src/test/ui/type/type-ascription-instead-of-statement-end.rs
new file mode 100644
index 000000000..1d5565ab5
--- /dev/null
+++ b/src/test/ui/type/type-ascription-instead-of-statement-end.rs
@@ -0,0 +1,10 @@
+#![feature(type_ascription)]
+
+fn main() {
+    println!("test"):
+    0; //~ ERROR expected type, found `0`
+}
+
+fn foo() {
+    println!("test"): 0; //~ ERROR expected type, found `0`
+}
diff --git a/src/test/ui/type/type-ascription-instead-of-statement-end.stderr b/src/test/ui/type/type-ascription-instead-of-statement-end.stderr
new file mode 100644
index 000000000..521ebcdf1
--- /dev/null
+++ b/src/test/ui/type/type-ascription-instead-of-statement-end.stderr
@@ -0,0 +1,24 @@
+error: expected type, found `0`
+  --> $DIR/type-ascription-instead-of-statement-end.rs:5:5
+   |
+LL |     println!("test"):
+   |                     - help: try using a semicolon: `;`
+LL |     0;
+   |     ^ expected type
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+   = note: see issue #23416 <https://github.com/rust-lang/rust/issues/23416> for more information
+
+error: expected type, found `0`
+  --> $DIR/type-ascription-instead-of-statement-end.rs:9:23
+   |
+LL |     println!("test"): 0;
+   |                     - ^ expected type
+   |                     |
+   |                     tried to parse a type due to this type ascription
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+   = note: see issue #23416 <https://github.com/rust-lang/rust/issues/23416> for more information
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/type/type-ascription-precedence.rs b/src/test/ui/type/type-ascription-precedence.rs
new file mode 100644
index 000000000..d3aef929b
--- /dev/null
+++ b/src/test/ui/type/type-ascription-precedence.rs
@@ -0,0 +1,54 @@
+// Operator precedence of type ascription
+// Type ascription has very high precedence, the same as operator `as`
+
+#![feature(type_ascription)]
+
+use std::ops::*;
+
+struct S;
+struct Z;
+
+impl Add<Z> for S {
+    type Output = S;
+    fn add(self, _rhs: Z) -> S { panic!() }
+}
+impl Mul<Z> for S {
+    type Output = S;
+    fn mul(self, _rhs: Z) -> S { panic!() }
+}
+impl Neg for S {
+    type Output = Z;
+    fn neg(self) -> Z { panic!() }
+}
+impl Deref for S {
+    type Target = Z;
+    fn deref(&self) -> &Z { panic!() }
+}
+
+fn main() {
+    &S: &S; // OK
+    (&S): &S; // OK
+    &(S: &S); //~ ERROR mismatched types
+
+    *S: Z; // OK
+    (*S): Z; // OK
+    *(S: Z); //~ ERROR mismatched types
+    //~^ ERROR type `Z` cannot be dereferenced
+
+    -S: Z; // OK
+    (-S): Z; // OK
+    -(S: Z); //~ ERROR mismatched types
+    //~^ ERROR cannot apply unary operator `-` to type `Z`
+
+    S + Z: Z; // OK
+    S + (Z: Z); // OK
+    (S + Z): Z; //~ ERROR mismatched types
+
+    S * Z: Z; // OK
+    S * (Z: Z); // OK
+    (S * Z): Z; //~ ERROR mismatched types
+
+    S .. S: S; // OK
+    S .. (S: S); // OK
+    (S .. S): S; //~ ERROR mismatched types
+}
diff --git a/src/test/ui/type/type-ascription-precedence.stderr b/src/test/ui/type/type-ascription-precedence.stderr
new file mode 100644
index 000000000..a8139063d
--- /dev/null
+++ b/src/test/ui/type/type-ascription-precedence.stderr
@@ -0,0 +1,66 @@
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-precedence.rs:31:7
+   |
+LL |     &(S: &S);
+   |       ^ expected `&S`, found struct `S`
+
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-precedence.rs:35:7
+   |
+LL |     *(S: Z);
+   |       ^ expected struct `Z`, found struct `S`
+
+error[E0614]: type `Z` cannot be dereferenced
+  --> $DIR/type-ascription-precedence.rs:35:5
+   |
+LL |     *(S: Z);
+   |     ^^^^^^^
+
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-precedence.rs:40:7
+   |
+LL |     -(S: Z);
+   |       ^ expected struct `Z`, found struct `S`
+
+error[E0600]: cannot apply unary operator `-` to type `Z`
+  --> $DIR/type-ascription-precedence.rs:40:5
+   |
+LL |     -(S: Z);
+   |     ^^^^^^^ cannot apply unary operator `-`
+   |
+note: an implementation of `std::ops::Neg` might be missing for `Z`
+  --> $DIR/type-ascription-precedence.rs:9:1
+   |
+LL | struct Z;
+   | ^^^^^^^^ must implement `std::ops::Neg`
+note: the following trait must be implemented
+  --> $SRC_DIR/core/src/ops/arith.rs:LL:COL
+   |
+LL | pub trait Neg {
+   | ^^^^^^^^^^^^^
+
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-precedence.rs:45:5
+   |
+LL |     (S + Z): Z;
+   |     ^^^^^^^ expected struct `Z`, found struct `S`
+
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-precedence.rs:49:5
+   |
+LL |     (S * Z): Z;
+   |     ^^^^^^^ expected struct `Z`, found struct `S`
+
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-precedence.rs:53:5
+   |
+LL |     (S .. S): S;
+   |     ^^^^^^^^ expected struct `S`, found struct `std::ops::Range`
+   |
+   = note: expected struct `S`
+              found struct `std::ops::Range<S>`
+
+error: aborting due to 8 previous errors
+
+Some errors have detailed explanations: E0308, E0600, E0614.
+For more information about an error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-ascription-soundness.rs b/src/test/ui/type/type-ascription-soundness.rs
new file mode 100644
index 000000000..d583fc213
--- /dev/null
+++ b/src/test/ui/type/type-ascription-soundness.rs
@@ -0,0 +1,13 @@
+// Type ascription doesn't lead to unsoundness
+
+#![feature(type_ascription)]
+
+fn main() {
+    let arr = &[1u8, 2, 3];
+    let ref x = arr: &[u8]; //~ ERROR mismatched types
+    let ref mut x = arr: &[u8]; //~ ERROR mismatched types
+    match arr: &[u8] { //~ ERROR mismatched types
+        ref x => {}
+    }
+    let _len = (arr: &[u8]).len(); //~ ERROR mismatched types
+}
diff --git a/src/test/ui/type/type-ascription-soundness.stderr b/src/test/ui/type/type-ascription-soundness.stderr
new file mode 100644
index 000000000..6ed940823
--- /dev/null
+++ b/src/test/ui/type/type-ascription-soundness.stderr
@@ -0,0 +1,39 @@
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-soundness.rs:7:17
+   |
+LL |     let ref x = arr: &[u8];
+   |                 ^^^ expected slice `[u8]`, found array `[u8; 3]`
+   |
+   = note: expected reference `&[u8]`
+              found reference `&[u8; 3]`
+
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-soundness.rs:8:21
+   |
+LL |     let ref mut x = arr: &[u8];
+   |                     ^^^ expected slice `[u8]`, found array `[u8; 3]`
+   |
+   = note: expected reference `&[u8]`
+              found reference `&[u8; 3]`
+
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-soundness.rs:9:11
+   |
+LL |     match arr: &[u8] {
+   |           ^^^ expected slice `[u8]`, found array `[u8; 3]`
+   |
+   = note: expected reference `&[u8]`
+              found reference `&[u8; 3]`
+
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-soundness.rs:12:17
+   |
+LL |     let _len = (arr: &[u8]).len();
+   |                 ^^^ expected slice `[u8]`, found array `[u8; 3]`
+   |
+   = note: expected reference `&[u8]`
+              found reference `&[u8; 3]`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-ascription-with-fn-call.fixed b/src/test/ui/type/type-ascription-with-fn-call.fixed
new file mode 100644
index 000000000..6d96c4303
--- /dev/null
+++ b/src/test/ui/type/type-ascription-with-fn-call.fixed
@@ -0,0 +1,9 @@
+// run-rustfix
+#![feature(type_ascription)]
+
+fn main() {
+    f()  ;
+    f(); //~ ERROR expected type, found function
+}
+
+fn f() {}
diff --git a/src/test/ui/type/type-ascription-with-fn-call.rs b/src/test/ui/type/type-ascription-with-fn-call.rs
new file mode 100644
index 000000000..ed4f7c904
--- /dev/null
+++ b/src/test/ui/type/type-ascription-with-fn-call.rs
@@ -0,0 +1,9 @@
+// run-rustfix
+#![feature(type_ascription)]
+
+fn main() {
+    f()  :
+    f(); //~ ERROR expected type, found function
+}
+
+fn f() {}
diff --git a/src/test/ui/type/type-ascription-with-fn-call.stderr b/src/test/ui/type/type-ascription-with-fn-call.stderr
new file mode 100644
index 000000000..d78fd08fd
--- /dev/null
+++ b/src/test/ui/type/type-ascription-with-fn-call.stderr
@@ -0,0 +1,11 @@
+error[E0573]: expected type, found function `f`
+  --> $DIR/type-ascription-with-fn-call.rs:6:5
+   |
+LL |     f()  :
+   |          - help: maybe you meant to write `;` here
+LL |     f();
+   |     ^^^ expecting a type here because of type ascription
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0573`.
diff --git a/src/test/ui/type/type-ascription.rs b/src/test/ui/type/type-ascription.rs
new file mode 100644
index 000000000..7adb07442
--- /dev/null
+++ b/src/test/ui/type/type-ascription.rs
@@ -0,0 +1,39 @@
+// run-pass
+
+#![allow(dead_code)]
+#![allow(unused_variables)]
+// Type ascription doesn't lead to unsoundness
+
+#![feature(type_ascription)]
+
+use std::mem;
+
+const C1: u8 = 10: u8;
+const C2: [u8; 1: usize] = [1];
+
+struct S {
+    a: u8
+}
+
+fn main() {
+    assert_eq!(C1.into(): i32, 10);
+    assert_eq!(C2[0], 1);
+
+    let s = S { a: 10: u8 };
+    let arr = &[1u8, 2, 3];
+
+    let mut v = arr.iter().cloned().collect(): Vec<_>;
+    v.push(4);
+    assert_eq!(v, [1, 2, 3, 4]);
+
+    let a = 1: u8;
+    let b = a.into(): u16;
+    assert_eq!(v[a.into(): usize], 2);
+    assert_eq!(mem::size_of_val(&a), 1);
+    assert_eq!(mem::size_of_val(&b), 2);
+    assert_eq!(b, 1: u16);
+
+    let mut v = Vec::new();
+    v: Vec<u8> = vec![1, 2, 3]; // Place expression type ascription
+    assert_eq!(v, [1u8, 2, 3]);
+}
diff --git a/src/test/ui/type/type-check-defaults.rs b/src/test/ui/type/type-check-defaults.rs
new file mode 100644
index 000000000..6a0a7ed33
--- /dev/null
+++ b/src/test/ui/type/type-check-defaults.rs
@@ -0,0 +1,27 @@
+use std::iter::FromIterator;
+use std::vec::IntoIter;
+use std::ops::Add;
+
+struct Foo<T, U: FromIterator<T>>(T, U);
+struct WellFormed<Z = Foo<i32, i32>>(Z);
+//~^ ERROR a value of type `i32` cannot be built from an iterator over elements of type `i32`
+struct WellFormedNoBounds<Z:?Sized = Foo<i32, i32>>(Z);
+//~^ ERROR a value of type `i32` cannot be built from an iterator over elements of type `i32`
+
+struct Bounds<T:Copy=String>(T);
+//~^ ERROR the trait bound `String: Copy` is not satisfied [E0277]
+
+struct WhereClause<T=String>(T) where T: Copy;
+//~^ ERROR the trait bound `String: Copy` is not satisfied [E0277]
+
+trait TraitBound<T:Copy=String> {}
+//~^ ERROR the trait bound `String: Copy` is not satisfied [E0277]
+
+trait Super<T: Copy> { }
+trait Base<T = String>: Super<T> { }
+//~^ ERROR the trait bound `T: Copy` is not satisfied [E0277]
+
+trait ProjectionPred<T:Iterator = IntoIter<i32>> where T::Item : Add<u8> {}
+//~^ ERROR cannot add `u8` to `i32` [E0277]
+
+fn main() { }
diff --git a/src/test/ui/type/type-check-defaults.stderr b/src/test/ui/type/type-check-defaults.stderr
new file mode 100644
index 000000000..56a9b5317
--- /dev/null
+++ b/src/test/ui/type/type-check-defaults.stderr
@@ -0,0 +1,81 @@
+error[E0277]: a value of type `i32` cannot be built from an iterator over elements of type `i32`
+  --> $DIR/type-check-defaults.rs:6:19
+   |
+LL | struct WellFormed<Z = Foo<i32, i32>>(Z);
+   |                   ^^^^^^^^^^^^^^^^^ value of type `i32` cannot be built from `std::iter::Iterator<Item=i32>`
+   |
+   = help: the trait `FromIterator<i32>` is not implemented for `i32`
+note: required by a bound in `Foo`
+  --> $DIR/type-check-defaults.rs:5:18
+   |
+LL | struct Foo<T, U: FromIterator<T>>(T, U);
+   |                  ^^^^^^^^^^^^^^^ required by this bound in `Foo`
+
+error[E0277]: a value of type `i32` cannot be built from an iterator over elements of type `i32`
+  --> $DIR/type-check-defaults.rs:8:27
+   |
+LL | struct WellFormedNoBounds<Z:?Sized = Foo<i32, i32>>(Z);
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^^ value of type `i32` cannot be built from `std::iter::Iterator<Item=i32>`
+   |
+   = help: the trait `FromIterator<i32>` is not implemented for `i32`
+note: required by a bound in `Foo`
+  --> $DIR/type-check-defaults.rs:5:18
+   |
+LL | struct Foo<T, U: FromIterator<T>>(T, U);
+   |                  ^^^^^^^^^^^^^^^ required by this bound in `Foo`
+
+error[E0277]: the trait bound `String: Copy` is not satisfied
+  --> $DIR/type-check-defaults.rs:11:17
+   |
+LL | struct Bounds<T:Copy=String>(T);
+   |                 ^^^^ the trait `Copy` is not implemented for `String`
+
+error[E0277]: the trait bound `String: Copy` is not satisfied
+  --> $DIR/type-check-defaults.rs:14:42
+   |
+LL | struct WhereClause<T=String>(T) where T: Copy;
+   |                                          ^^^^ the trait `Copy` is not implemented for `String`
+
+error[E0277]: the trait bound `String: Copy` is not satisfied
+  --> $DIR/type-check-defaults.rs:17:20
+   |
+LL | trait TraitBound<T:Copy=String> {}
+   |                    ^^^^ the trait `Copy` is not implemented for `String`
+
+error[E0277]: the trait bound `T: Copy` is not satisfied
+  --> $DIR/type-check-defaults.rs:21:25
+   |
+LL | trait Base<T = String>: Super<T> { }
+   |                         ^^^^^^^^ the trait `Copy` is not implemented for `T`
+   |
+note: required by a bound in `Super`
+  --> $DIR/type-check-defaults.rs:20:16
+   |
+LL | trait Super<T: Copy> { }
+   |                ^^^^ required by this bound in `Super`
+help: consider further restricting type parameter `T`
+   |
+LL | trait Base<T = String>: Super<T> where T: std::marker::Copy { }
+   |                                  ++++++++++++++++++++++++++
+
+error[E0277]: cannot add `u8` to `i32`
+  --> $DIR/type-check-defaults.rs:24:66
+   |
+LL | trait ProjectionPred<T:Iterator = IntoIter<i32>> where T::Item : Add<u8> {}
+   |                                                                  ^^^^^^^ no implementation for `i32 + u8`
+   |
+   = help: the trait `Add<u8>` is not implemented for `i32`
+   = help: the following other types implement trait `Add<Rhs>`:
+             <&'a f32 as Add<f32>>
+             <&'a f64 as Add<f64>>
+             <&'a i128 as Add<i128>>
+             <&'a i16 as Add<i16>>
+             <&'a i32 as Add<i32>>
+             <&'a i64 as Add<i64>>
+             <&'a i8 as Add<i8>>
+             <&'a isize as Add<isize>>
+           and 48 others
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type/type-check/assignment-expected-bool.rs b/src/test/ui/type/type-check/assignment-expected-bool.rs
new file mode 100644
index 000000000..191939bdb
--- /dev/null
+++ b/src/test/ui/type/type-check/assignment-expected-bool.rs
@@ -0,0 +1,34 @@
+// The purpose of this text is to ensure that we get good
+// diagnostics when a `bool` is expected but that due to
+// an assignment expression `x = y` the type is `()`.
+
+fn main() {
+    let _: bool = 0 = 0; //~ ERROR mismatched types [E0308]
+
+    let _: bool = match 0 {
+        0 => 0 = 0, //~ ERROR mismatched types [E0308]
+        _ => 0 = 0, //~ ERROR mismatched types [E0308]
+    };
+
+    let _: bool = match true {
+        true => 0 = 0, //~ ERROR mismatched types [E0308]
+        _ => (),
+    };
+
+    if 0 = 0 {} //~ ERROR mismatched types [E0308]
+
+    let _: bool = if { 0 = 0 } { //~ ERROR mismatched types [E0308]
+        0 = 0 //~ ERROR mismatched types [E0308]
+    } else {
+        0 = 0 //~ ERROR mismatched types [E0308]
+    };
+
+    let _ = (0 = 0) //~ ERROR mismatched types [E0308]
+        && { 0 = 0 } //~ ERROR mismatched types [E0308]
+        || (0 = 0); //~ ERROR mismatched types [E0308]
+
+    // A test to check that not expecting `bool` behaves well:
+    let _: usize = 0 = 0;
+    //~^ ERROR mismatched types [E0308]
+    //~| ERROR invalid left-hand side of assignment [E0070]
+}
diff --git a/src/test/ui/type/type-check/assignment-expected-bool.stderr b/src/test/ui/type/type-check/assignment-expected-bool.stderr
new file mode 100644
index 000000000..e2b821f7b
--- /dev/null
+++ b/src/test/ui/type/type-check/assignment-expected-bool.stderr
@@ -0,0 +1,141 @@
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:6:19
+   |
+LL |     let _: bool = 0 = 0;
+   |                   ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |     let _: bool = 0 == 0;
+   |                     ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:9:14
+   |
+LL |         0 => 0 = 0,
+   |              ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |         0 => 0 == 0,
+   |                ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:10:14
+   |
+LL |         _ => 0 = 0,
+   |              ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |         _ => 0 == 0,
+   |                ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:14:17
+   |
+LL |         true => 0 = 0,
+   |                 ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |         true => 0 == 0,
+   |                   ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:18:8
+   |
+LL |     if 0 = 0 {}
+   |        ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |     if 0 == 0 {}
+   |          ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:20:24
+   |
+LL |     let _: bool = if { 0 = 0 } {
+   |                        ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |     let _: bool = if { 0 == 0 } {
+   |                          ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:21:9
+   |
+LL |         0 = 0
+   |         ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |         0 == 0
+   |           ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:23:9
+   |
+LL |         0 = 0
+   |         ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |         0 == 0
+   |           ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:26:13
+   |
+LL |     let _ = (0 = 0)
+   |             ^^^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |     let _ = (0 == 0)
+   |                ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:27:14
+   |
+LL |         && { 0 = 0 }
+   |              ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |         && { 0 == 0 }
+   |                ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:28:12
+   |
+LL |         || (0 = 0);
+   |            ^^^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |         || (0 == 0);
+   |               ~~
+
+error[E0070]: invalid left-hand side of assignment
+  --> $DIR/assignment-expected-bool.rs:31:22
+   |
+LL |     let _: usize = 0 = 0;
+   |                    - ^
+   |                    |
+   |                    cannot assign to this expression
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-expected-bool.rs:31:20
+   |
+LL |     let _: usize = 0 = 0;
+   |            -----   ^^^^^ expected `usize`, found `()`
+   |            |
+   |            expected due to this
+
+error: aborting due to 13 previous errors
+
+Some errors have detailed explanations: E0070, E0308.
+For more information about an error, try `rustc --explain E0070`.
diff --git a/src/test/ui/type/type-check/assignment-in-if.rs b/src/test/ui/type/type-check/assignment-in-if.rs
new file mode 100644
index 000000000..8da7b32b4
--- /dev/null
+++ b/src/test/ui/type/type-check/assignment-in-if.rs
@@ -0,0 +1,43 @@
+// Test that the parser does not attempt to parse struct literals
+// within assignments in if expressions.
+
+#![allow(unused_parens)]
+
+struct Foo {
+    foo: usize
+}
+
+fn main() {
+    let x = 1;
+    let y: Foo;
+
+    // `x { ... }` should not be interpreted as a struct literal here
+    if x = x {
+        //~^ ERROR mismatched types
+        println!("{}", x);
+    }
+    // Explicit parentheses on the left should match behavior of above
+    if (x = x) {
+        //~^ ERROR mismatched types
+        println!("{}", x);
+    }
+    // The struct literal interpretation is fine with explicit parentheses on the right
+    if y = (Foo { foo: x }) {
+        //~^ ERROR mismatched types
+        println!("{}", x);
+    }
+    // "invalid left-hand side of assignment" error is suppresed
+    if 3 = x {
+        //~^ ERROR mismatched types
+        println!("{}", x);
+    }
+    if (
+        if true {
+            x = 4 //~ ERROR mismatched types
+        } else {
+            x = 5 //~ ERROR mismatched types
+        }
+    ) {
+        println!("{}", x);
+    }
+}
diff --git a/src/test/ui/type/type-check/assignment-in-if.stderr b/src/test/ui/type/type-check/assignment-in-if.stderr
new file mode 100644
index 000000000..f4ef44e24
--- /dev/null
+++ b/src/test/ui/type/type-check/assignment-in-if.stderr
@@ -0,0 +1,69 @@
+error[E0308]: mismatched types
+  --> $DIR/assignment-in-if.rs:15:8
+   |
+LL |     if x = x {
+   |        ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |     if x == x {
+   |          ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-in-if.rs:20:8
+   |
+LL |     if (x = x) {
+   |        ^^^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |     if (x == x) {
+   |           ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-in-if.rs:25:8
+   |
+LL |     if y = (Foo { foo: x }) {
+   |        ^^^^^^^^^^^^^^^^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |     if y == (Foo { foo: x }) {
+   |          ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-in-if.rs:30:8
+   |
+LL |     if 3 = x {
+   |        ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |     if 3 == x {
+   |          ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-in-if.rs:36:13
+   |
+LL |             x = 4
+   |             ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |             x == 4
+   |               ~~
+
+error[E0308]: mismatched types
+  --> $DIR/assignment-in-if.rs:38:13
+   |
+LL |             x = 5
+   |             ^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to compare for equality
+   |
+LL |             x == 5
+   |               ~~
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-check/cannot_infer_local_or_array.rs b/src/test/ui/type/type-check/cannot_infer_local_or_array.rs
new file mode 100644
index 000000000..af7552523
--- /dev/null
+++ b/src/test/ui/type/type-check/cannot_infer_local_or_array.rs
@@ -0,0 +1,3 @@
+fn main() {
+    let x = []; //~ ERROR type annotations needed
+}
diff --git a/src/test/ui/type/type-check/cannot_infer_local_or_array.stderr b/src/test/ui/type/type-check/cannot_infer_local_or_array.stderr
new file mode 100644
index 000000000..e823bad26
--- /dev/null
+++ b/src/test/ui/type/type-check/cannot_infer_local_or_array.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed for `[_; 0]`
+  --> $DIR/cannot_infer_local_or_array.rs:2:9
+   |
+LL |     let x = [];
+   |         ^   -- type must be known at this point
+   |
+help: consider giving `x` an explicit type, where the placeholders `_` are specified
+   |
+LL |     let x: [_; 0] = [];
+   |          ++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type/type-check/cannot_infer_local_or_vec.rs b/src/test/ui/type/type-check/cannot_infer_local_or_vec.rs
new file mode 100644
index 000000000..e72ddabf3
--- /dev/null
+++ b/src/test/ui/type/type-check/cannot_infer_local_or_vec.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let x = vec![];
+    //~^ ERROR type annotations needed
+}
diff --git a/src/test/ui/type/type-check/cannot_infer_local_or_vec.stderr b/src/test/ui/type/type-check/cannot_infer_local_or_vec.stderr
new file mode 100644
index 000000000..b63d2a3b6
--- /dev/null
+++ b/src/test/ui/type/type-check/cannot_infer_local_or_vec.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed for `Vec<T>`
+  --> $DIR/cannot_infer_local_or_vec.rs:2:9
+   |
+LL |     let x = vec![];
+   |         ^
+   |
+help: consider giving `x` an explicit type, where the type for type parameter `T` is specified
+   |
+LL |     let x: Vec<T> = vec![];
+   |          ++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type/type-check/cannot_infer_local_or_vec_in_tuples.rs b/src/test/ui/type/type-check/cannot_infer_local_or_vec_in_tuples.rs
new file mode 100644
index 000000000..d21456439
--- /dev/null
+++ b/src/test/ui/type/type-check/cannot_infer_local_or_vec_in_tuples.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let (x, ) = (vec![], );
+    //~^ ERROR type annotations needed
+}
diff --git a/src/test/ui/type/type-check/cannot_infer_local_or_vec_in_tuples.stderr b/src/test/ui/type/type-check/cannot_infer_local_or_vec_in_tuples.stderr
new file mode 100644
index 000000000..be60cda68
--- /dev/null
+++ b/src/test/ui/type/type-check/cannot_infer_local_or_vec_in_tuples.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed for `(Vec<T>,)`
+  --> $DIR/cannot_infer_local_or_vec_in_tuples.rs:2:9
+   |
+LL |     let (x, ) = (vec![], );
+   |         ^^^^^
+   |
+help: consider giving this pattern a type, where the type for type parameter `T` is specified
+   |
+LL |     let (x, ): (Vec<T>,) = (vec![], );
+   |              +++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type/type-check/issue-22897.rs b/src/test/ui/type/type-check/issue-22897.rs
new file mode 100644
index 000000000..8171a0ef1
--- /dev/null
+++ b/src/test/ui/type/type-check/issue-22897.rs
@@ -0,0 +1,5 @@
+fn main() { }
+
+fn unconstrained_type() {
+    []; //~ ERROR type annotations needed
+}
diff --git a/src/test/ui/type/type-check/issue-22897.stderr b/src/test/ui/type/type-check/issue-22897.stderr
new file mode 100644
index 000000000..fae7b7926
--- /dev/null
+++ b/src/test/ui/type/type-check/issue-22897.stderr
@@ -0,0 +1,9 @@
+error[E0282]: type annotations needed
+  --> $DIR/issue-22897.rs:4:5
+   |
+LL |     [];
+   |     ^^ cannot infer type for array `[_; 0]`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type/type-check/issue-40294.rs b/src/test/ui/type/type-check/issue-40294.rs
new file mode 100644
index 000000000..5493a4e5f
--- /dev/null
+++ b/src/test/ui/type/type-check/issue-40294.rs
@@ -0,0 +1,13 @@
+trait Foo: Sized {
+    fn foo(self);
+}
+
+fn foo<'a,'b,T>(x: &'a T, y: &'b T)
+    where &'a T : Foo, //~ ERROR type annotations needed
+          &'b T : Foo
+{
+    x.foo();
+    y.foo();
+}
+
+fn main() { }
diff --git a/src/test/ui/type/type-check/issue-40294.stderr b/src/test/ui/type/type-check/issue-40294.stderr
new file mode 100644
index 000000000..75feb5698
--- /dev/null
+++ b/src/test/ui/type/type-check/issue-40294.stderr
@@ -0,0 +1,11 @@
+error[E0283]: type annotations needed: cannot satisfy `&'a T: Foo`
+  --> $DIR/issue-40294.rs:6:19
+   |
+LL |     where &'a T : Foo,
+   |                   ^^^
+   |
+   = note: cannot satisfy `&'a T: Foo`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0283`.
diff --git a/src/test/ui/type/type-check/issue-41314.rs b/src/test/ui/type/type-check/issue-41314.rs
new file mode 100644
index 000000000..cbd39f5f9
--- /dev/null
+++ b/src/test/ui/type/type-check/issue-41314.rs
@@ -0,0 +1,10 @@
+enum X {
+    Y(u32)
+}
+
+fn main() {
+    match X::Y(0) {
+        X::Y { number } => {}
+        //~^ ERROR tuple variant `X::Y` written as struct variant
+    }
+}
diff --git a/src/test/ui/type/type-check/issue-41314.stderr b/src/test/ui/type/type-check/issue-41314.stderr
new file mode 100644
index 000000000..4a9bf6106
--- /dev/null
+++ b/src/test/ui/type/type-check/issue-41314.stderr
@@ -0,0 +1,14 @@
+error[E0769]: tuple variant `X::Y` written as struct variant
+  --> $DIR/issue-41314.rs:7:9
+   |
+LL |         X::Y { number } => {}
+   |         ^^^^^^^^^^^^^^^
+   |
+help: use the tuple variant pattern syntax instead
+   |
+LL |         X::Y(number) => {}
+   |             ~~~~~~~~
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0769`.
diff --git a/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.rs b/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.rs
new file mode 100644
index 000000000..c39ab9544
--- /dev/null
+++ b/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.rs
@@ -0,0 +1,27 @@
+fn main() {
+    let mut i: i64;
+    // Expected type is an inference variable `?T`
+    // because the `match` is used as a statement.
+    // This is the "initial" type of the `coercion`.
+    match i {
+        // Add `bool` to the overall `coercion`.
+        0 => true,
+
+        // Necessary to cause the ICE:
+        1 => true,
+
+        // Suppose that we had `let _: bool = match i { ... }`.
+        // In that case, as the expected type would be `bool`,
+        // we would suggest `i == 1` as a fix.
+        //
+        // However, no type error happens when checking `i = 1` because `expected == ?T`,
+        // which will unify with `typeof(i = 1) == ()`.
+        //
+        // However, in #67273, we would delay the unification of this arm with the above
+        // because we used the hitherto accumulated coercion as opposed to the "initial" type.
+        2 => i = 1,
+        //~^ ERROR `match` arms have incompatible types
+
+        _ => (),
+    }
+}
diff --git a/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.stderr b/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.stderr
new file mode 100644
index 000000000..a431fe89c
--- /dev/null
+++ b/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.stderr
@@ -0,0 +1,22 @@
+error[E0308]: `match` arms have incompatible types
+  --> $DIR/issue-67273-assignment-match-prior-arm-bool-expected-unit.rs:22:14
+   |
+LL | /     match i {
+LL | |         // Add `bool` to the overall `coercion`.
+LL | |         0 => true,
+   | |              ---- this is found to be of type `bool`
+LL | |
+LL | |         // Necessary to cause the ICE:
+LL | |         1 => true,
+   | |              ---- this is found to be of type `bool`
+...  |
+LL | |         2 => i = 1,
+   | |              ^^^^^ expected `bool`, found `()`
+...  |
+LL | |         _ => (),
+LL | |     }
+   | |_____- `match` arms have incompatible types
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-check/issue-88577-check-fn-with-more-than-65535-arguments.rs b/src/test/ui/type/type-check/issue-88577-check-fn-with-more-than-65535-arguments.rs
new file mode 100644
index 000000000..e50cc5865
--- /dev/null
+++ b/src/test/ui/type/type-check/issue-88577-check-fn-with-more-than-65535-arguments.rs
@@ -0,0 +1,12 @@
+macro_rules! many_args {
+    ([$($t:tt)*]#$($h:tt)*) => {
+        many_args!{[$($t)*$($t)*]$($h)*}
+    };
+    ([$($t:tt)*]) => {
+        fn _f($($t: ()),*) {} //~ ERROR function can not have more than 65535 arguments
+    }
+}
+
+many_args!{[_]########## ######}
+
+fn main() {}
diff --git a/src/test/ui/type/type-check/issue-88577-check-fn-with-more-than-65535-arguments.stderr b/src/test/ui/type/type-check/issue-88577-check-fn-with-more-than-65535-arguments.stderr
new file mode 100644
index 000000000..615fd2ccb
--- /dev/null
+++ b/src/test/ui/type/type-check/issue-88577-check-fn-with-more-than-65535-arguments.stderr
@@ -0,0 +1,13 @@
+error: function can not have more than 65535 arguments
+  --> $DIR/issue-88577-check-fn-with-more-than-65535-arguments.rs:6:24
+   |
+LL |           fn _f($($t: ()),*) {}
+   |  ________________________^
+LL | |     }
+LL | | }
+LL | |
+LL | | many_args!{[_]########## ######}
+   | |____________^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type/type-check/missing_trait_impl.rs b/src/test/ui/type/type-check/missing_trait_impl.rs
new file mode 100644
index 000000000..0e3e703a2
--- /dev/null
+++ b/src/test/ui/type/type-check/missing_trait_impl.rs
@@ -0,0 +1,16 @@
+fn main() {
+}
+
+fn foo<T>(x: T, y: T) {
+    let z = x + y; //~ ERROR cannot add `T` to `T`
+}
+
+fn bar<T>(x: T) {
+    x += x; //~ ERROR binary assignment operation `+=` cannot be applied to type `T`
+}
+
+fn baz<T>(x: T) {
+    let y = -x; //~ ERROR cannot apply unary operator `-` to type `T`
+    let y = !x; //~ ERROR cannot apply unary operator `!` to type `T`
+    let y = *x; //~ ERROR type `T` cannot be dereferenced
+}
diff --git a/src/test/ui/type/type-check/missing_trait_impl.stderr b/src/test/ui/type/type-check/missing_trait_impl.stderr
new file mode 100644
index 000000000..2b58cd418
--- /dev/null
+++ b/src/test/ui/type/type-check/missing_trait_impl.stderr
@@ -0,0 +1,58 @@
+error[E0369]: cannot add `T` to `T`
+  --> $DIR/missing_trait_impl.rs:5:15
+   |
+LL |     let z = x + y;
+   |             - ^ - T
+   |             |
+   |             T
+   |
+help: consider restricting type parameter `T`
+   |
+LL | fn foo<T: std::ops::Add>(x: T, y: T) {
+   |         +++++++++++++++
+
+error[E0368]: binary assignment operation `+=` cannot be applied to type `T`
+  --> $DIR/missing_trait_impl.rs:9:5
+   |
+LL |     x += x;
+   |     -^^^^^
+   |     |
+   |     cannot use `+=` on type `T`
+   |
+help: consider restricting type parameter `T`
+   |
+LL | fn bar<T: std::ops::AddAssign>(x: T) {
+   |         +++++++++++++++++++++
+
+error[E0600]: cannot apply unary operator `-` to type `T`
+  --> $DIR/missing_trait_impl.rs:13:13
+   |
+LL |     let y = -x;
+   |             ^^ cannot apply unary operator `-`
+   |
+help: consider restricting type parameter `T`
+   |
+LL | fn baz<T: std::ops::Neg>(x: T) {
+   |         +++++++++++++++
+
+error[E0600]: cannot apply unary operator `!` to type `T`
+  --> $DIR/missing_trait_impl.rs:14:13
+   |
+LL |     let y = !x;
+   |             ^^ cannot apply unary operator `!`
+   |
+help: consider restricting type parameter `T`
+   |
+LL | fn baz<T: std::ops::Not>(x: T) {
+   |         +++++++++++++++
+
+error[E0614]: type `T` cannot be dereferenced
+  --> $DIR/missing_trait_impl.rs:15:13
+   |
+LL |     let y = *x;
+   |             ^^
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0368, E0369, E0600, E0614.
+For more information about an error, try `rustc --explain E0368`.
diff --git a/src/test/ui/type/type-check/unknown_type_for_closure.rs b/src/test/ui/type/type-check/unknown_type_for_closure.rs
new file mode 100644
index 000000000..167687c18
--- /dev/null
+++ b/src/test/ui/type/type-check/unknown_type_for_closure.rs
@@ -0,0 +1,17 @@
+fn infer_in_arg() {
+    let x = |b: Vec<_>| {}; //~ ERROR E0282
+}
+
+fn empty_pattern() {
+    let x = |_| {}; //~ ERROR type annotations needed
+}
+
+fn infer_ty() {
+    let x = |k: _| {}; //~ ERROR type annotations needed
+}
+
+fn ambig_return() {
+    let x = || -> Vec<_> { Vec::new() }; //~ ERROR type annotations needed
+}
+
+fn main() {}
diff --git a/src/test/ui/type/type-check/unknown_type_for_closure.stderr b/src/test/ui/type/type-check/unknown_type_for_closure.stderr
new file mode 100644
index 000000000..9ae97f390
--- /dev/null
+++ b/src/test/ui/type/type-check/unknown_type_for_closure.stderr
@@ -0,0 +1,37 @@
+error[E0282]: type annotations needed
+  --> $DIR/unknown_type_for_closure.rs:2:13
+   |
+LL |     let x = |b: Vec<_>| {};
+   |             ^^^^^^^^^^^^^^ cannot infer type for struct `Vec<_>`
+
+error[E0282]: type annotations needed
+  --> $DIR/unknown_type_for_closure.rs:6:14
+   |
+LL |     let x = |_| {};
+   |              ^
+   |
+help: consider giving this closure parameter an explicit type
+   |
+LL |     let x = |_: _| {};
+   |               +++
+
+error[E0282]: type annotations needed
+  --> $DIR/unknown_type_for_closure.rs:10:14
+   |
+LL |     let x = |k: _| {};
+   |              ^ cannot infer type
+
+error[E0282]: type annotations needed
+  --> $DIR/unknown_type_for_closure.rs:14:28
+   |
+LL |     let x = || -> Vec<_> { Vec::new() };
+   |                            ^^^^^^^^ cannot infer type of the type parameter `T` declared on the struct `Vec`
+   |
+help: consider specifying the generic argument
+   |
+LL |     let x = || -> Vec<_> { Vec::<T>::new() };
+   |                               +++++
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type/type-dependent-def-issue-49241.rs b/src/test/ui/type/type-dependent-def-issue-49241.rs
new file mode 100644
index 000000000..f37f093d9
--- /dev/null
+++ b/src/test/ui/type/type-dependent-def-issue-49241.rs
@@ -0,0 +1,6 @@
+fn main() {
+    let v = vec![0];
+    const l: usize = v.count(); //~ ERROR attempt to use a non-constant value in a constant
+    let s: [u32; l] = v.into_iter().collect();
+    //~^ERROR evaluation of constant value failed
+}
diff --git a/src/test/ui/type/type-dependent-def-issue-49241.stderr b/src/test/ui/type/type-dependent-def-issue-49241.stderr
new file mode 100644
index 000000000..02f267c6c
--- /dev/null
+++ b/src/test/ui/type/type-dependent-def-issue-49241.stderr
@@ -0,0 +1,18 @@
+error[E0435]: attempt to use a non-constant value in a constant
+  --> $DIR/type-dependent-def-issue-49241.rs:3:22
+   |
+LL |     const l: usize = v.count();
+   |     -------          ^ non-constant value
+   |     |
+   |     help: consider using `let` instead of `const`: `let l`
+
+error[E0080]: evaluation of constant value failed
+  --> $DIR/type-dependent-def-issue-49241.rs:4:18
+   |
+LL |     let s: [u32; l] = v.into_iter().collect();
+   |                  ^ referenced constant has errors
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0080, E0435.
+For more information about an error, try `rustc --explain E0080`.
diff --git a/src/test/ui/type/type-error-break-tail.rs b/src/test/ui/type/type-error-break-tail.rs
new file mode 100644
index 000000000..d4e3e93d0
--- /dev/null
+++ b/src/test/ui/type/type-error-break-tail.rs
@@ -0,0 +1,8 @@
+fn loop_ending() -> i32 {
+    loop {
+        if false { break; } //~ ERROR mismatched types
+        return 42;
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type/type-error-break-tail.stderr b/src/test/ui/type/type-error-break-tail.stderr
new file mode 100644
index 000000000..16dc6475c
--- /dev/null
+++ b/src/test/ui/type/type-error-break-tail.stderr
@@ -0,0 +1,15 @@
+error[E0308]: mismatched types
+  --> $DIR/type-error-break-tail.rs:3:20
+   |
+LL | fn loop_ending() -> i32 {
+   |                     --- expected `i32` because of return type
+LL |     loop {
+LL |         if false { break; }
+   |                    ^^^^^
+   |                    |
+   |                    expected `i32`, found `()`
+   |                    help: give it a value of the expected type: `break 42`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-mismatch-multiple.rs b/src/test/ui/type/type-mismatch-multiple.rs
new file mode 100644
index 000000000..55d6ceef1
--- /dev/null
+++ b/src/test/ui/type/type-mismatch-multiple.rs
@@ -0,0 +1,7 @@
+// Checking that the compiler reports multiple type errors at once
+
+fn main() { let a: bool = 1; let b: i32 = true; }
+//~^ ERROR mismatched types
+//~| expected `bool`, found integer
+//~| ERROR mismatched types
+//~| expected `i32`, found `bool`
diff --git a/src/test/ui/type/type-mismatch-multiple.stderr b/src/test/ui/type/type-mismatch-multiple.stderr
new file mode 100644
index 000000000..2e8654d31
--- /dev/null
+++ b/src/test/ui/type/type-mismatch-multiple.stderr
@@ -0,0 +1,19 @@
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch-multiple.rs:3:27
+   |
+LL | fn main() { let a: bool = 1; let b: i32 = true; }
+   |                    ----   ^ expected `bool`, found integer
+   |                    |
+   |                    expected due to this
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch-multiple.rs:3:43
+   |
+LL | fn main() { let a: bool = 1; let b: i32 = true; }
+   |                                     ---   ^^^^ expected `i32`, found `bool`
+   |                                     |
+   |                                     expected due to this
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-mismatch-same-crate-name.rs b/src/test/ui/type/type-mismatch-same-crate-name.rs
new file mode 100644
index 000000000..c9cdc874c
--- /dev/null
+++ b/src/test/ui/type/type-mismatch-same-crate-name.rs
@@ -0,0 +1,27 @@
+// aux-build:crate_a1.rs
+// aux-build:crate_a2.rs
+
+// This tests the extra note reported when a type error deals with
+// seemingly identical types.
+// The main use case of this error is when there are two crates
+// (generally different versions of the same crate) with the same name
+// causing a type mismatch. Here, we simulate that error using block-scoped
+// aliased `extern crate` declarations.
+
+fn main() {
+    let foo2 = {extern crate crate_a2 as a; a::Foo};
+    let bar2 = {extern crate crate_a2 as a; a::bar()};
+    {
+        extern crate crate_a1 as a;
+        a::try_foo(foo2);
+        //~^ ERROR mismatched types
+        //~| perhaps two different versions of crate `crate_a1`
+        //~| expected struct `main::a::Foo`
+        a::try_bar(bar2);
+        //~^ ERROR mismatched types
+        //~| perhaps two different versions of crate `crate_a1`
+        //~| expected trait `main::a::Bar`
+        //~| expected struct `Box<(dyn main::a::Bar + 'static)>`
+        //~| found struct `Box<dyn main::a::Bar>`
+    }
+}
diff --git a/src/test/ui/type/type-mismatch-same-crate-name.stderr b/src/test/ui/type/type-mismatch-same-crate-name.stderr
new file mode 100644
index 000000000..783f747fa
--- /dev/null
+++ b/src/test/ui/type/type-mismatch-same-crate-name.stderr
@@ -0,0 +1,35 @@
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch-same-crate-name.rs:16:20
+   |
+LL |         a::try_foo(foo2);
+   |         ---------- ^^^^ expected struct `main::a::Foo`, found a different struct `main::a::Foo`
+   |         |
+   |         arguments to this function are incorrect
+   |
+   = note: perhaps two different versions of crate `crate_a1` are being used?
+note: function defined here
+  --> $DIR/auxiliary/crate_a1.rs:10:8
+   |
+LL | pub fn try_foo(x: Foo){}
+   |        ^^^^^^^
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch-same-crate-name.rs:20:20
+   |
+LL |         a::try_bar(bar2);
+   |         ---------- ^^^^ expected trait `main::a::Bar`, found a different trait `main::a::Bar`
+   |         |
+   |         arguments to this function are incorrect
+   |
+   = note: expected struct `Box<(dyn main::a::Bar + 'static)>`
+              found struct `Box<dyn main::a::Bar>`
+   = note: perhaps two different versions of crate `crate_a1` are being used?
+note: function defined here
+  --> $DIR/auxiliary/crate_a1.rs:11:8
+   |
+LL | pub fn try_bar(x: Box<Bar>){}
+   |        ^^^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-mismatch.rs b/src/test/ui/type/type-mismatch.rs
new file mode 100644
index 000000000..11bfa3a72
--- /dev/null
+++ b/src/test/ui/type/type-mismatch.rs
@@ -0,0 +1,78 @@
+#![allow(non_camel_case_types)]
+
+trait Qux {}
+struct A;
+struct B;
+impl Qux for A {}
+impl Qux for B {}
+
+struct Foo<T, U: Qux = A, V: Qux = B>(T, U, V);
+
+struct foo;
+struct bar;
+
+fn want<T>(t: T) {}
+
+fn have_usize(f: usize) {
+    want::<foo>(f); //~ ERROR mismatched types
+    want::<bar>(f); //~ ERROR mismatched types
+    want::<Foo<usize>>(f); //~ ERROR mismatched types
+    want::<Foo<usize, B>>(f); //~ ERROR mismatched types
+    want::<Foo<foo>>(f); //~ ERROR mismatched types
+    want::<Foo<foo, B>>(f); //~ ERROR mismatched types
+    want::<Foo<bar>>(f); //~ ERROR mismatched types
+    want::<Foo<bar, B>>(f); //~ ERROR mismatched types
+}
+
+fn have_foo(f: foo) {
+    want::<usize>(f); //~ ERROR mismatched types
+    want::<bar>(f); //~ ERROR mismatched types
+    want::<Foo<usize>>(f); //~ ERROR mismatched types
+    want::<Foo<usize, B>>(f); //~ ERROR mismatched types
+    want::<Foo<foo>>(f); //~ ERROR mismatched types
+    want::<Foo<foo, B>>(f); //~ ERROR mismatched types
+    want::<Foo<bar>>(f); //~ ERROR mismatched types
+    want::<Foo<bar, B>>(f); //~ ERROR mismatched types
+}
+
+fn have_foo_foo(f: Foo<foo>) {
+    want::<usize>(f); //~ ERROR mismatched types
+    want::<foo>(f); //~ ERROR mismatched types
+    want::<bar>(f); //~ ERROR mismatched types
+    want::<Foo<usize>>(f); //~ ERROR mismatched types
+    want::<Foo<usize, B>>(f); //~ ERROR mismatched types
+    want::<Foo<foo, B>>(f); //~ ERROR mismatched types
+    want::<Foo<bar>>(f); //~ ERROR mismatched types
+    want::<Foo<bar, B>>(f); //~ ERROR mismatched types
+    want::<&Foo<foo>>(f); //~ ERROR mismatched types
+    want::<&Foo<foo, B>>(f); //~ ERROR mismatched types
+}
+
+fn have_foo_foo_b(f: Foo<foo, B>) {
+    want::<usize>(f); //~ ERROR mismatched types
+    want::<foo>(f); //~ ERROR mismatched types
+    want::<bar>(f); //~ ERROR mismatched types
+    want::<Foo<usize>>(f); //~ ERROR mismatched types
+    want::<Foo<usize, B>>(f); //~ ERROR mismatched types
+    want::<Foo<foo>>(f); //~ ERROR mismatched types
+    want::<Foo<bar>>(f); //~ ERROR mismatched types
+    want::<Foo<bar, B>>(f); //~ ERROR mismatched types
+    want::<&Foo<foo>>(f); //~ ERROR mismatched types
+    want::<&Foo<foo, B>>(f); //~ ERROR mismatched types
+}
+
+fn have_foo_foo_b_a(f: Foo<foo, B, A>) {
+    want::<usize>(f); //~ ERROR mismatched types
+    want::<foo>(f); //~ ERROR mismatched types
+    want::<bar>(f); //~ ERROR mismatched types
+    want::<Foo<usize>>(f); //~ ERROR mismatched types
+    want::<Foo<usize, B>>(f); //~ ERROR mismatched types
+    want::<Foo<foo>>(f); //~ ERROR mismatched types
+    want::<Foo<foo, B>>(f); //~ ERROR mismatched types
+    want::<Foo<bar>>(f); //~ ERROR mismatched types
+    want::<Foo<bar, B>>(f); //~ ERROR mismatched types
+    want::<&Foo<foo>>(f); //~ ERROR mismatched types
+    want::<&Foo<foo, B>>(f); //~ ERROR mismatched types
+}
+
+fn main() {}
diff --git a/src/test/ui/type/type-mismatch.stderr b/src/test/ui/type/type-mismatch.stderr
new file mode 100644
index 000000000..6c187bad0
--- /dev/null
+++ b/src/test/ui/type/type-mismatch.stderr
@@ -0,0 +1,751 @@
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:17:17
+   |
+LL |     want::<foo>(f);
+   |     ----------- ^ expected struct `foo`, found `usize`
+   |     |
+   |     arguments to this function are incorrect
+   |
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:18:17
+   |
+LL |     want::<bar>(f);
+   |     ----------- ^ expected struct `bar`, found `usize`
+   |     |
+   |     arguments to this function are incorrect
+   |
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:19:24
+   |
+LL |     want::<Foo<usize>>(f);
+   |     ------------------ ^ expected struct `Foo`, found `usize`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<usize>`
+                found type `usize`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:20:27
+   |
+LL |     want::<Foo<usize, B>>(f);
+   |     --------------------- ^ expected struct `Foo`, found `usize`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<usize, B>`
+                found type `usize`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:21:22
+   |
+LL |     want::<Foo<foo>>(f);
+   |     ---------------- ^ expected struct `Foo`, found `usize`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<foo>`
+                found type `usize`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:22:25
+   |
+LL |     want::<Foo<foo, B>>(f);
+   |     ------------------- ^ expected struct `Foo`, found `usize`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<foo, B>`
+                found type `usize`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:23:22
+   |
+LL |     want::<Foo<bar>>(f);
+   |     ---------------- ^ expected struct `Foo`, found `usize`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<bar>`
+                found type `usize`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:24:25
+   |
+LL |     want::<Foo<bar, B>>(f);
+   |     ------------------- ^ expected struct `Foo`, found `usize`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<bar, B>`
+                found type `usize`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:28:19
+   |
+LL |     want::<usize>(f);
+   |     ------------- ^ expected `usize`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:29:17
+   |
+LL |     want::<bar>(f);
+   |     ----------- ^ expected struct `bar`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:30:24
+   |
+LL |     want::<Foo<usize>>(f);
+   |     ------------------ ^ expected struct `Foo`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<usize>`
+              found struct `foo`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:31:27
+   |
+LL |     want::<Foo<usize, B>>(f);
+   |     --------------------- ^ expected struct `Foo`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<usize, B>`
+              found struct `foo`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:32:22
+   |
+LL |     want::<Foo<foo>>(f);
+   |     ---------------- ^ expected struct `Foo`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<foo>`
+              found struct `foo`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:33:25
+   |
+LL |     want::<Foo<foo, B>>(f);
+   |     ------------------- ^ expected struct `Foo`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<foo, B>`
+              found struct `foo`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:34:22
+   |
+LL |     want::<Foo<bar>>(f);
+   |     ---------------- ^ expected struct `Foo`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<bar>`
+              found struct `foo`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:35:25
+   |
+LL |     want::<Foo<bar, B>>(f);
+   |     ------------------- ^ expected struct `Foo`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<bar, B>`
+              found struct `foo`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:39:19
+   |
+LL |     want::<usize>(f);
+   |     ------------- ^ expected `usize`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected type `usize`
+            found struct `Foo<foo>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:40:17
+   |
+LL |     want::<foo>(f);
+   |     ----------- ^ expected struct `foo`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `foo`
+              found struct `Foo<foo>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:41:17
+   |
+LL |     want::<bar>(f);
+   |     ----------- ^ expected struct `bar`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `bar`
+              found struct `Foo<foo>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:42:24
+   |
+LL |     want::<Foo<usize>>(f);
+   |     ------------------ ^ expected `usize`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<usize>`
+              found struct `Foo<foo>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:43:27
+   |
+LL |     want::<Foo<usize, B>>(f);
+   |     --------------------- ^ expected `usize`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<usize, B>`
+              found struct `Foo<foo, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:44:25
+   |
+LL |     want::<Foo<foo, B>>(f);
+   |     ------------------- ^ expected struct `B`, found struct `A`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<_, B>`
+              found struct `Foo<_, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:45:22
+   |
+LL |     want::<Foo<bar>>(f);
+   |     ---------------- ^ expected struct `bar`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<bar>`
+              found struct `Foo<foo>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:46:25
+   |
+LL |     want::<Foo<bar, B>>(f);
+   |     ------------------- ^ expected struct `bar`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<bar, B>`
+              found struct `Foo<foo, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:47:23
+   |
+LL |     want::<&Foo<foo>>(f);
+   |     ----------------- ^
+   |     |                 |
+   |     |                 expected `&Foo<foo>`, found struct `Foo`
+   |     |                 help: consider borrowing here: `&f`
+   |     arguments to this function are incorrect
+   |
+   = note: expected reference `&Foo<foo>`
+                 found struct `Foo<foo>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:48:26
+   |
+LL |     want::<&Foo<foo, B>>(f);
+   |     -------------------- ^ expected `&Foo<foo, B>`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected reference `&Foo<foo, B>`
+                 found struct `Foo<foo>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:52:19
+   |
+LL |     want::<usize>(f);
+   |     ------------- ^ expected `usize`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected type `usize`
+            found struct `Foo<foo, B>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:53:17
+   |
+LL |     want::<foo>(f);
+   |     ----------- ^ expected struct `foo`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `foo`
+              found struct `Foo<foo, B>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:54:17
+   |
+LL |     want::<bar>(f);
+   |     ----------- ^ expected struct `bar`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `bar`
+              found struct `Foo<foo, B>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:55:24
+   |
+LL |     want::<Foo<usize>>(f);
+   |     ------------------ ^ expected `usize`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<usize, A>`
+              found struct `Foo<foo, B>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:56:27
+   |
+LL |     want::<Foo<usize, B>>(f);
+   |     --------------------- ^ expected `usize`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<usize, _>`
+              found struct `Foo<foo, _>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:57:22
+   |
+LL |     want::<Foo<foo>>(f);
+   |     ---------------- ^ expected struct `A`, found struct `B`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<_, A>`
+              found struct `Foo<_, B>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:58:22
+   |
+LL |     want::<Foo<bar>>(f);
+   |     ---------------- ^ expected struct `bar`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<bar, A>`
+              found struct `Foo<foo, B>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:59:25
+   |
+LL |     want::<Foo<bar, B>>(f);
+   |     ------------------- ^ expected struct `bar`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<bar, _>`
+              found struct `Foo<foo, _>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:60:23
+   |
+LL |     want::<&Foo<foo>>(f);
+   |     ----------------- ^ expected `&Foo<foo>`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected reference `&Foo<foo>`
+                 found struct `Foo<foo, B>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:61:26
+   |
+LL |     want::<&Foo<foo, B>>(f);
+   |     -------------------- ^
+   |     |                    |
+   |     |                    expected `&Foo<foo, B>`, found struct `Foo`
+   |     |                    help: consider borrowing here: `&f`
+   |     arguments to this function are incorrect
+   |
+   = note: expected reference `&Foo<foo, B>`
+                 found struct `Foo<foo, B>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:65:19
+   |
+LL |     want::<usize>(f);
+   |     ------------- ^ expected `usize`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected type `usize`
+            found struct `Foo<foo, B, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:66:17
+   |
+LL |     want::<foo>(f);
+   |     ----------- ^ expected struct `foo`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `foo`
+              found struct `Foo<foo, B, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:67:17
+   |
+LL |     want::<bar>(f);
+   |     ----------- ^ expected struct `bar`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `bar`
+              found struct `Foo<foo, B, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:68:24
+   |
+LL |     want::<Foo<usize>>(f);
+   |     ------------------ ^ expected `usize`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<usize, A, B>`
+              found struct `Foo<foo, B, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:69:27
+   |
+LL |     want::<Foo<usize, B>>(f);
+   |     --------------------- ^ expected `usize`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<usize, _, B>`
+              found struct `Foo<foo, _, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:70:22
+   |
+LL |     want::<Foo<foo>>(f);
+   |     ---------------- ^ expected struct `A`, found struct `B`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<_, A, B>`
+              found struct `Foo<_, B, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:71:25
+   |
+LL |     want::<Foo<foo, B>>(f);
+   |     ------------------- ^ expected struct `B`, found struct `A`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<_, _, B>`
+              found struct `Foo<_, _, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:72:22
+   |
+LL |     want::<Foo<bar>>(f);
+   |     ---------------- ^ expected struct `bar`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<bar, A, B>`
+              found struct `Foo<foo, B, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:73:25
+   |
+LL |     want::<Foo<bar, B>>(f);
+   |     ------------------- ^ expected struct `bar`, found struct `foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected struct `Foo<bar, _, B>`
+              found struct `Foo<foo, _, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:74:23
+   |
+LL |     want::<&Foo<foo>>(f);
+   |     ----------------- ^ expected `&Foo<foo>`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected reference `&Foo<foo>`
+                 found struct `Foo<foo, B, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error[E0308]: mismatched types
+  --> $DIR/type-mismatch.rs:75:26
+   |
+LL |     want::<&Foo<foo, B>>(f);
+   |     -------------------- ^ expected `&Foo<foo, B>`, found struct `Foo`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected reference `&Foo<foo, B>`
+                 found struct `Foo<foo, B, A>`
+note: function defined here
+  --> $DIR/type-mismatch.rs:14:4
+   |
+LL | fn want<T>(t: T) {}
+   |    ^^^^    ----
+
+error: aborting due to 47 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-parameter-defaults-referencing-Self-ppaux.rs b/src/test/ui/type/type-parameter-defaults-referencing-Self-ppaux.rs
new file mode 100644
index 000000000..444453dc6
--- /dev/null
+++ b/src/test/ui/type/type-parameter-defaults-referencing-Self-ppaux.rs
@@ -0,0 +1,17 @@
+// Test a default that references `Self` which is then used in an
+// object type. Issue #18956. In this case, the value is supplied by
+// the user, but pretty-printing the type during the error message
+// caused an ICE.
+
+trait MyAdd<Rhs=Self> { fn add(&self, other: &Rhs) -> Self; }
+
+impl MyAdd for i32 {
+    fn add(&self, other: &i32) -> i32 { *self + *other }
+}
+
+fn main() {
+    let x: i32 = 5;
+    let y = x as dyn MyAdd<i32>;
+    //~^ ERROR E0038
+    //~| ERROR cast to unsized type: `i32` as `dyn MyAdd<i32>`
+}
diff --git a/src/test/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr b/src/test/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr
new file mode 100644
index 000000000..8a296dc7e
--- /dev/null
+++ b/src/test/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr
@@ -0,0 +1,31 @@
+error[E0620]: cast to unsized type: `i32` as `dyn MyAdd<i32>`
+  --> $DIR/type-parameter-defaults-referencing-Self-ppaux.rs:14:13
+   |
+LL |     let y = x as dyn MyAdd<i32>;
+   |             ^^^^^^^^^^^^^^^^^^^
+   |
+help: consider using a box or reference as appropriate
+  --> $DIR/type-parameter-defaults-referencing-Self-ppaux.rs:14:13
+   |
+LL |     let y = x as dyn MyAdd<i32>;
+   |             ^
+
+error[E0038]: the trait `MyAdd` cannot be made into an object
+  --> $DIR/type-parameter-defaults-referencing-Self-ppaux.rs:14:18
+   |
+LL |     let y = x as dyn MyAdd<i32>;
+   |                  ^^^^^^^^^^^^^^ `MyAdd` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/type-parameter-defaults-referencing-Self-ppaux.rs:6:55
+   |
+LL | trait MyAdd<Rhs=Self> { fn add(&self, other: &Rhs) -> Self; }
+   |       -----                                           ^^^^ ...because method `add` references the `Self` type in its return type
+   |       |
+   |       this trait cannot be made into an object...
+   = help: consider moving `add` to another trait
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0038, E0620.
+For more information about an error, try `rustc --explain E0038`.
diff --git a/src/test/ui/type/type-parameter-defaults-referencing-Self.rs b/src/test/ui/type/type-parameter-defaults-referencing-Self.rs
new file mode 100644
index 000000000..e5c81556e
--- /dev/null
+++ b/src/test/ui/type/type-parameter-defaults-referencing-Self.rs
@@ -0,0 +1,11 @@
+// Test a default that references `Self` which is then used in an object type.
+// Issue #18956.
+
+trait Foo<T=Self> {
+    fn method(&self);
+}
+
+fn foo(x: &dyn Foo) { }
+//~^ ERROR the type parameter `T` must be explicitly specified
+
+fn main() { }
diff --git a/src/test/ui/type/type-parameter-defaults-referencing-Self.stderr b/src/test/ui/type/type-parameter-defaults-referencing-Self.stderr
new file mode 100644
index 000000000..67a4745b3
--- /dev/null
+++ b/src/test/ui/type/type-parameter-defaults-referencing-Self.stderr
@@ -0,0 +1,14 @@
+error[E0393]: the type parameter `T` must be explicitly specified
+  --> $DIR/type-parameter-defaults-referencing-Self.rs:8:16
+   |
+LL | trait Foo<T=Self> {
+   | ----------------- type parameter `T` must be specified for this
+...
+LL | fn foo(x: &dyn Foo) { }
+   |                ^^^ help: set the type parameter to the desired type: `Foo<T>`
+   |
+   = note: because of the default `Self` reference, type parameters must be specified on object types
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0393`.
diff --git a/src/test/ui/type/type-parameter-names.rs b/src/test/ui/type/type-parameter-names.rs
new file mode 100644
index 000000000..b54a3fae0
--- /dev/null
+++ b/src/test/ui/type/type-parameter-names.rs
@@ -0,0 +1,12 @@
+// Test that we print out the names of type parameters correctly in
+// our error messages.
+
+fn foo<Foo, Bar>(x: Foo) -> Bar {
+    x
+//~^ ERROR mismatched types
+//~| expected type parameter `Bar`, found type parameter `Foo`
+//~| expected type parameter `Bar`
+//~| found type parameter `Foo`
+}
+
+fn main() {}
diff --git a/src/test/ui/type/type-parameter-names.stderr b/src/test/ui/type/type-parameter-names.stderr
new file mode 100644
index 000000000..f0ca8afca
--- /dev/null
+++ b/src/test/ui/type/type-parameter-names.stderr
@@ -0,0 +1,19 @@
+error[E0308]: mismatched types
+  --> $DIR/type-parameter-names.rs:5:5
+   |
+LL | fn foo<Foo, Bar>(x: Foo) -> Bar {
+   |        ---  ---             --- expected `Bar` because of return type
+   |        |    |
+   |        |    expected type parameter
+   |        found type parameter
+LL |     x
+   |     ^ expected type parameter `Bar`, found type parameter `Foo`
+   |
+   = note: expected type parameter `Bar`
+              found type parameter `Foo`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-params-in-different-spaces-1.rs b/src/test/ui/type/type-params-in-different-spaces-1.rs
new file mode 100644
index 000000000..6efd14d37
--- /dev/null
+++ b/src/test/ui/type/type-params-in-different-spaces-1.rs
@@ -0,0 +1,18 @@
+use std::ops::Add;
+
+trait BrokenAdd: Copy + Add<Output=Self> {
+    fn broken_add<T>(&self, rhs: T) -> Self {
+        *self + rhs //~  ERROR mismatched types
+                    //~| expected type parameter `Self`, found type parameter `T`
+                    //~| expected type parameter `Self`
+                    //~| found type parameter `T`
+    }
+}
+
+impl<T: Copy + Add<Output=T>> BrokenAdd for T {}
+
+pub fn main() {
+    let foo: u8 = 0;
+    let x: u8 = foo.broken_add("hello darkness my old friend".to_string());
+    println!("{}", x);
+}
diff --git a/src/test/ui/type/type-params-in-different-spaces-1.stderr b/src/test/ui/type/type-params-in-different-spaces-1.stderr
new file mode 100644
index 000000000..4e73e10a3
--- /dev/null
+++ b/src/test/ui/type/type-params-in-different-spaces-1.stderr
@@ -0,0 +1,18 @@
+error[E0308]: mismatched types
+  --> $DIR/type-params-in-different-spaces-1.rs:5:17
+   |
+LL | trait BrokenAdd: Copy + Add<Output=Self> {
+   | ---------------------------------------- expected type parameter
+LL |     fn broken_add<T>(&self, rhs: T) -> Self {
+   |                   - found type parameter
+LL |         *self + rhs
+   |                 ^^^ expected type parameter `Self`, found type parameter `T`
+   |
+   = note: expected type parameter `Self`
+              found type parameter `T`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-params-in-different-spaces-2.rs b/src/test/ui/type/type-params-in-different-spaces-2.rs
new file mode 100644
index 000000000..1211e465b
--- /dev/null
+++ b/src/test/ui/type/type-params-in-different-spaces-2.rs
@@ -0,0 +1,21 @@
+// Test static calls to make sure that we align the Self and input
+// type parameters on a trait correctly.
+
+trait Tr<T> : Sized {
+    fn op(_: T) -> Self;
+}
+
+trait A:    Tr<Self> {
+    fn test<U>(u: U) -> Self {
+        Tr::op(u)   //~ ERROR E0277
+    }
+}
+
+trait B<T>: Tr<T> {
+    fn test<U>(u: U) -> Self {
+        Tr::op(u)   //~ ERROR E0277
+    }
+}
+
+fn main() {
+}
diff --git a/src/test/ui/type/type-params-in-different-spaces-2.stderr b/src/test/ui/type/type-params-in-different-spaces-2.stderr
new file mode 100644
index 000000000..53610985f
--- /dev/null
+++ b/src/test/ui/type/type-params-in-different-spaces-2.stderr
@@ -0,0 +1,25 @@
+error[E0277]: the trait bound `Self: Tr<U>` is not satisfied
+  --> $DIR/type-params-in-different-spaces-2.rs:10:9
+   |
+LL |         Tr::op(u)
+   |         ^^^^^^ the trait `Tr<U>` is not implemented for `Self`
+   |
+help: consider further restricting `Self`
+   |
+LL |     fn test<U>(u: U) -> Self where Self: Tr<U> {
+   |                              +++++++++++++++++
+
+error[E0277]: the trait bound `Self: Tr<U>` is not satisfied
+  --> $DIR/type-params-in-different-spaces-2.rs:16:9
+   |
+LL |         Tr::op(u)
+   |         ^^^^^^ the trait `Tr<U>` is not implemented for `Self`
+   |
+help: consider further restricting `Self`
+   |
+LL |     fn test<U>(u: U) -> Self where Self: Tr<U> {
+   |                              +++++++++++++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type/type-params-in-different-spaces-3.rs b/src/test/ui/type/type-params-in-different-spaces-3.rs
new file mode 100644
index 000000000..ac7b0c11f
--- /dev/null
+++ b/src/test/ui/type/type-params-in-different-spaces-3.rs
@@ -0,0 +1,7 @@
+trait Tr : Sized {
+    fn test<X>(u: X) -> Self {
+        u   //~ ERROR mismatched types
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/type/type-params-in-different-spaces-3.stderr b/src/test/ui/type/type-params-in-different-spaces-3.stderr
new file mode 100644
index 000000000..c538d6731
--- /dev/null
+++ b/src/test/ui/type/type-params-in-different-spaces-3.stderr
@@ -0,0 +1,20 @@
+error[E0308]: mismatched types
+  --> $DIR/type-params-in-different-spaces-3.rs:3:9
+   |
+LL | trait Tr : Sized {
+   | ---------------- expected type parameter
+LL |     fn test<X>(u: X) -> Self {
+   |             -           ---- expected `Self` because of return type
+   |             |
+   |             found type parameter
+LL |         u
+   |         ^ expected type parameter `Self`, found type parameter `X`
+   |
+   = note: expected type parameter `Self`
+              found type parameter `X`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-path-err-node-types.rs b/src/test/ui/type/type-path-err-node-types.rs
new file mode 100644
index 000000000..b3795772e
--- /dev/null
+++ b/src/test/ui/type/type-path-err-node-types.rs
@@ -0,0 +1,26 @@
+// Type arguments in unresolved entities (reporting errors before type checking)
+// should have their types recorded.
+
+trait Tr<T> {}
+
+fn local_type() {
+    let _: Nonexistent<u8, Assoc = u16>; //~ ERROR cannot find type `Nonexistent` in this scope
+}
+
+fn ufcs_trait() {
+    <u8 as Tr<u8>>::nonexistent(); //~ ERROR cannot find method or associated constant `nonexistent`
+}
+
+fn ufcs_item() {
+    NonExistent::Assoc::<u8>; //~ ERROR undeclared type `NonExistent`
+}
+
+fn method() {
+    nonexistent.nonexistent::<u8>(); //~ ERROR cannot find value `nonexistent`
+}
+
+fn closure() {
+    let _ = |a, b: _| -> _ { 0 }; //~ ERROR type annotations needed
+}
+
+fn main() {}
diff --git a/src/test/ui/type/type-path-err-node-types.stderr b/src/test/ui/type/type-path-err-node-types.stderr
new file mode 100644
index 000000000..c1ae10efa
--- /dev/null
+++ b/src/test/ui/type/type-path-err-node-types.stderr
@@ -0,0 +1,39 @@
+error[E0433]: failed to resolve: use of undeclared type `NonExistent`
+  --> $DIR/type-path-err-node-types.rs:15:5
+   |
+LL |     NonExistent::Assoc::<u8>;
+   |     ^^^^^^^^^^^ use of undeclared type `NonExistent`
+
+error[E0412]: cannot find type `Nonexistent` in this scope
+  --> $DIR/type-path-err-node-types.rs:7:12
+   |
+LL |     let _: Nonexistent<u8, Assoc = u16>;
+   |            ^^^^^^^^^^^ not found in this scope
+
+error[E0576]: cannot find method or associated constant `nonexistent` in trait `Tr`
+  --> $DIR/type-path-err-node-types.rs:11:21
+   |
+LL |     <u8 as Tr<u8>>::nonexistent();
+   |                     ^^^^^^^^^^^ not found in `Tr`
+
+error[E0425]: cannot find value `nonexistent` in this scope
+  --> $DIR/type-path-err-node-types.rs:19:5
+   |
+LL |     nonexistent.nonexistent::<u8>();
+   |     ^^^^^^^^^^^ not found in this scope
+
+error[E0282]: type annotations needed
+  --> $DIR/type-path-err-node-types.rs:23:14
+   |
+LL |     let _ = |a, b: _| -> _ { 0 };
+   |              ^
+   |
+help: consider giving this closure parameter an explicit type
+   |
+LL |     let _ = |a: _, b: _| -> _ { 0 };
+   |               +++
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0282, E0412, E0425, E0433, E0576.
+For more information about an error, try `rustc --explain E0282`.
diff --git a/src/test/ui/type/type-recursive-box-shadowed.rs b/src/test/ui/type/type-recursive-box-shadowed.rs
new file mode 100644
index 000000000..e141c2149
--- /dev/null
+++ b/src/test/ui/type/type-recursive-box-shadowed.rs
@@ -0,0 +1,12 @@
+//FIXME(compiler-errors): This fixup should suggest the full box path, not just `Box`
+
+struct Box<T> {
+    t: T,
+}
+
+struct Foo {
+    //~^ ERROR recursive type `Foo` has infinite size
+    inner: Foo,
+}
+
+fn main() {}
diff --git a/src/test/ui/type/type-recursive-box-shadowed.stderr b/src/test/ui/type/type-recursive-box-shadowed.stderr
new file mode 100644
index 000000000..c22d848f3
--- /dev/null
+++ b/src/test/ui/type/type-recursive-box-shadowed.stderr
@@ -0,0 +1,17 @@
+error[E0072]: recursive type `Foo` has infinite size
+  --> $DIR/type-recursive-box-shadowed.rs:7:1
+   |
+LL | struct Foo {
+   | ^^^^^^^^^^ recursive type has infinite size
+LL |
+LL |     inner: Foo,
+   |            --- recursive without indirection
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Foo` representable
+   |
+LL |     inner: Box<Foo>,
+   |            ++++   +
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0072`.
diff --git a/src/test/ui/type/type-recursive.rs b/src/test/ui/type/type-recursive.rs
new file mode 100644
index 000000000..e8084f0d0
--- /dev/null
+++ b/src/test/ui/type/type-recursive.rs
@@ -0,0 +1,30 @@
+struct T1 { //~ ERROR E0072
+    foo: isize,
+    foolish: T1,
+}
+
+struct T2 { //~ ERROR E0072
+    inner: Option<T2>,
+}
+
+type OptionT3 = Option<T3>;
+
+struct T3 { //~ ERROR E0072
+    inner: OptionT3,
+}
+
+struct T4(Option<T4>); //~ ERROR E0072
+
+enum T5 { //~ ERROR E0072
+    Variant(Option<T5>),
+}
+
+enum T6 { //~ ERROR E0072
+    Variant{ field: Option<T6> },
+}
+
+struct T7 { //~ ERROR E0072
+    foo: std::cell::Cell<Option<T7>>,
+}
+
+fn main() { }
diff --git a/src/test/ui/type/type-recursive.stderr b/src/test/ui/type/type-recursive.stderr
new file mode 100644
index 000000000..320271028
--- /dev/null
+++ b/src/test/ui/type/type-recursive.stderr
@@ -0,0 +1,95 @@
+error[E0072]: recursive type `T1` has infinite size
+  --> $DIR/type-recursive.rs:1:1
+   |
+LL | struct T1 {
+   | ^^^^^^^^^ recursive type has infinite size
+LL |     foo: isize,
+LL |     foolish: T1,
+   |              -- recursive without indirection
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `T1` representable
+   |
+LL |     foolish: Box<T1>,
+   |              ++++  +
+
+error[E0072]: recursive type `T2` has infinite size
+  --> $DIR/type-recursive.rs:6:1
+   |
+LL | struct T2 {
+   | ^^^^^^^^^ recursive type has infinite size
+LL |     inner: Option<T2>,
+   |            ---------- recursive without indirection
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `T2` representable
+   |
+LL |     inner: Option<Box<T2>>,
+   |                   ++++  +
+
+error[E0072]: recursive type `T3` has infinite size
+  --> $DIR/type-recursive.rs:12:1
+   |
+LL | struct T3 {
+   | ^^^^^^^^^ recursive type has infinite size
+LL |     inner: OptionT3,
+   |            -------- recursive without indirection
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `T3` representable
+   |
+LL |     inner: Box<OptionT3>,
+   |            ++++        +
+
+error[E0072]: recursive type `T4` has infinite size
+  --> $DIR/type-recursive.rs:16:1
+   |
+LL | struct T4(Option<T4>);
+   | ^^^^^^^^^ ---------- recursive without indirection
+   | |
+   | recursive type has infinite size
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `T4` representable
+   |
+LL | struct T4(Option<Box<T4>>);
+   |                  ++++  +
+
+error[E0072]: recursive type `T5` has infinite size
+  --> $DIR/type-recursive.rs:18:1
+   |
+LL | enum T5 {
+   | ^^^^^^^ recursive type has infinite size
+LL |     Variant(Option<T5>),
+   |             ---------- recursive without indirection
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `T5` representable
+   |
+LL |     Variant(Option<Box<T5>>),
+   |                    ++++  +
+
+error[E0072]: recursive type `T6` has infinite size
+  --> $DIR/type-recursive.rs:22:1
+   |
+LL | enum T6 {
+   | ^^^^^^^ recursive type has infinite size
+LL |     Variant{ field: Option<T6> },
+   |                     ---------- recursive without indirection
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `T6` representable
+   |
+LL |     Variant{ field: Option<Box<T6>> },
+   |                            ++++  +
+
+error[E0072]: recursive type `T7` has infinite size
+  --> $DIR/type-recursive.rs:26:1
+   |
+LL | struct T7 {
+   | ^^^^^^^^^ recursive type has infinite size
+LL |     foo: std::cell::Cell<Option<T7>>,
+   |          --------------------------- recursive without indirection
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `T7` representable
+   |
+LL |     foo: Box<std::cell::Cell<Option<T7>>>,
+   |          ++++                           +
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0072`.
diff --git a/src/test/ui/type/type-shadow.rs b/src/test/ui/type/type-shadow.rs
new file mode 100644
index 000000000..48a68a390
--- /dev/null
+++ b/src/test/ui/type/type-shadow.rs
@@ -0,0 +1,8 @@
+fn main() {
+    type X = isize;
+    type Y = X;
+    if true {
+        type X = &'static str;
+        let y: Y = "hello"; //~ ERROR mismatched types
+    }
+}
diff --git a/src/test/ui/type/type-shadow.stderr b/src/test/ui/type/type-shadow.stderr
new file mode 100644
index 000000000..25b4bff4d
--- /dev/null
+++ b/src/test/ui/type/type-shadow.stderr
@@ -0,0 +1,11 @@
+error[E0308]: mismatched types
+  --> $DIR/type-shadow.rs:6:20
+   |
+LL |         let y: Y = "hello";
+   |                -   ^^^^^^^ expected `isize`, found `&str`
+   |                |
+   |                expected due to this
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/type/type-unsatisfiable.rs b/src/test/ui/type/type-unsatisfiable.rs
new file mode 100644
index 000000000..7fbbb50dc
--- /dev/null
+++ b/src/test/ui/type/type-unsatisfiable.rs
@@ -0,0 +1,59 @@
+// revisions: lib usage
+//[lib] compile-flags: --crate-type=lib
+//[lib] build-pass
+
+use std::ops::Sub;
+trait Vector2 {
+    type ScalarType;
+
+    fn from_values(x: Self::ScalarType, y: Self::ScalarType) -> Self
+    where
+        Self: Sized;
+
+    fn x(&self) -> Self::ScalarType;
+    fn y(&self) -> Self::ScalarType;
+}
+
+impl<T> Sub for dyn Vector2<ScalarType = T>
+where
+    T: Sub<Output = T>,
+    (dyn Vector2<ScalarType = T>): Sized,
+{
+    type Output = dyn Vector2<ScalarType = T>;
+
+    fn sub(self, rhs: Self) -> Self::Output {
+        Self::from_values(self.x() - rhs.x(), self.y() - rhs.y())
+    }
+}
+
+struct Vec2 {
+    x: i32,
+    y: i32,
+}
+
+impl Vector2 for Vec2 {
+    type ScalarType = i32;
+
+    fn from_values(x: Self::ScalarType, y: Self::ScalarType) -> Self
+    where
+        Self: Sized,
+    {
+        Self { x, y }
+    }
+
+    fn x(&self) -> Self::ScalarType {
+        self.x
+    }
+    fn y(&self) -> Self::ScalarType {
+        self.y
+    }
+}
+
+#[cfg(usage)]
+fn main() {
+    let hey: Box<dyn Vector2<ScalarType = i32>> = Box::new(Vec2 { x: 1, y: 2 });
+    let word: Box<dyn Vector2<ScalarType = i32>> = Box::new(Vec2 { x: 1, y: 2 });
+
+    let bar = *hey - *word;
+    //[usage]~^ ERROR cannot subtract
+}
diff --git a/src/test/ui/type/type-unsatisfiable.usage.stderr b/src/test/ui/type/type-unsatisfiable.usage.stderr
new file mode 100644
index 000000000..56e2e30af
--- /dev/null
+++ b/src/test/ui/type/type-unsatisfiable.usage.stderr
@@ -0,0 +1,11 @@
+error[E0369]: cannot subtract `(dyn Vector2<ScalarType = i32> + 'static)` from `dyn Vector2<ScalarType = i32>`
+  --> $DIR/type-unsatisfiable.rs:57:20
+   |
+LL |     let bar = *hey - *word;
+   |               ---- ^ ----- (dyn Vector2<ScalarType = i32> + 'static)
+   |               |
+   |               dyn Vector2<ScalarType = i32>
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0369`.
diff --git a/src/test/ui/type_length_limit.polonius.stderr b/src/test/ui/type_length_limit.polonius.stderr
new file mode 100644
index 000000000..82d066b2a
--- /dev/null
+++ b/src/test/ui/type_length_limit.polonius.stderr
@@ -0,0 +1,11 @@
+error: reached the type-length limit while instantiating `std::mem::drop::<Option<((((...,....., ...), ..., ...), ..., ...)>>`
+  --> $SRC_DIR/core/src/mem/mod.rs:LL:COL
+   |
+LL | pub fn drop<T>(_x: T) {}
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the full type name has been written to '$TEST_BUILD_DIR/type_length_limit.polonius/type_length_limit.long-type.txt'
+   = help: consider adding a `#![type_length_limit="8"]` attribute to your crate
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type_length_limit.rs b/src/test/ui/type_length_limit.rs
new file mode 100644
index 000000000..ce6fdf811
--- /dev/null
+++ b/src/test/ui/type_length_limit.rs
@@ -0,0 +1,29 @@
+// build-fail
+// error-pattern: reached the type-length limit while instantiating
+// compile-flags: -Copt-level=0
+// normalize-stderr-test: ".nll/" -> "/"
+
+// Test that the type length limit can be changed.
+// The exact type depends on optimizations, so disable them.
+
+#![allow(dead_code)]
+#![type_length_limit="4"]
+
+macro_rules! link {
+    ($id:ident, $t:ty) => {
+        pub type $id = ($t, $t, $t);
+    }
+}
+
+link! { A, B }
+link! { B, C }
+link! { C, D }
+link! { D, E }
+link! { E, F }
+link! { F, G }
+
+pub struct G;
+
+fn main() {
+    drop::<Option<A>>(None);
+}
diff --git a/src/test/ui/type_length_limit.stderr b/src/test/ui/type_length_limit.stderr
new file mode 100644
index 000000000..1508b84c1
--- /dev/null
+++ b/src/test/ui/type_length_limit.stderr
@@ -0,0 +1,20 @@
+error: reached the type-length limit while instantiating `std::mem::drop::<Option<((((...,....., ...), ..., ...), ..., ...)>>`
+  --> $SRC_DIR/core/src/mem/mod.rs:LL:COL
+   |
+LL | pub fn drop<T>(_x: T) {}
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the full type name has been written to '$TEST_BUILD_DIR/type_length_limit/type_length_limit.long-type.txt'
+   = help: consider adding a `#![type_length_limit="8"]` attribute to your crate
+
+error: reached the type-length limit while instantiating `<[closure@std::rt::lang_start<()...e<()>>::call_once - shim(vtable)`
+  --> $SRC_DIR/core/src/ops/function.rs:LL:COL
+   |
+LL |     extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the full type name has been written to '$TEST_BUILD_DIR/type_length_limit/type_length_limit.long-type.txt'
+   = help: consider adding a `#![type_length_limit="8"]` attribute to your crate
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/typeck/assign-non-lval-derefmut.fixed b/src/test/ui/typeck/assign-non-lval-derefmut.fixed
new file mode 100644
index 000000000..0c23199af
--- /dev/null
+++ b/src/test/ui/typeck/assign-non-lval-derefmut.fixed
@@ -0,0 +1,15 @@
+// run-rustfix
+
+fn main() {
+    let x = std::sync::Mutex::new(1usize);
+    *x.lock().unwrap() = 2;
+    //~^ ERROR invalid left-hand side of assignment
+    *x.lock().unwrap() += 1;
+    //~^ ERROR binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
+
+    let mut y = x.lock().unwrap();
+    *y = 2;
+    //~^ ERROR mismatched types
+    *y += 1;
+    //~^ ERROR binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
+}
diff --git a/src/test/ui/typeck/assign-non-lval-derefmut.rs b/src/test/ui/typeck/assign-non-lval-derefmut.rs
new file mode 100644
index 000000000..ec1882f52
--- /dev/null
+++ b/src/test/ui/typeck/assign-non-lval-derefmut.rs
@@ -0,0 +1,15 @@
+// run-rustfix
+
+fn main() {
+    let x = std::sync::Mutex::new(1usize);
+    x.lock().unwrap() = 2;
+    //~^ ERROR invalid left-hand side of assignment
+    x.lock().unwrap() += 1;
+    //~^ ERROR binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
+
+    let mut y = x.lock().unwrap();
+    y = 2;
+    //~^ ERROR mismatched types
+    y += 1;
+    //~^ ERROR binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
+}
diff --git a/src/test/ui/typeck/assign-non-lval-derefmut.stderr b/src/test/ui/typeck/assign-non-lval-derefmut.stderr
new file mode 100644
index 000000000..a6fcdfe21
--- /dev/null
+++ b/src/test/ui/typeck/assign-non-lval-derefmut.stderr
@@ -0,0 +1,58 @@
+error[E0070]: invalid left-hand side of assignment
+  --> $DIR/assign-non-lval-derefmut.rs:5:23
+   |
+LL |     x.lock().unwrap() = 2;
+   |     ----------------- ^
+   |     |
+   |     cannot assign to this expression
+   |
+help: consider dereferencing here to assign to the mutably borrowed value
+   |
+LL |     *x.lock().unwrap() = 2;
+   |     +
+
+error[E0368]: binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
+  --> $DIR/assign-non-lval-derefmut.rs:7:5
+   |
+LL |     x.lock().unwrap() += 1;
+   |     -----------------^^^^^
+   |     |
+   |     cannot use `+=` on type `MutexGuard<'_, usize>`
+   |
+help: `+=` can be used on `usize`, you can dereference `x.lock().unwrap()`
+   |
+LL |     *x.lock().unwrap() += 1;
+   |     +
+
+error[E0308]: mismatched types
+  --> $DIR/assign-non-lval-derefmut.rs:11:9
+   |
+LL |     let mut y = x.lock().unwrap();
+   |                 ----------------- expected due to this value
+LL |     y = 2;
+   |         ^ expected struct `MutexGuard`, found integer
+   |
+   = note: expected struct `MutexGuard<'_, usize>`
+                found type `{integer}`
+help: consider dereferencing here to assign to the mutably borrowed value
+   |
+LL |     *y = 2;
+   |     +
+
+error[E0368]: binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
+  --> $DIR/assign-non-lval-derefmut.rs:13:5
+   |
+LL |     y += 1;
+   |     -^^^^^
+   |     |
+   |     cannot use `+=` on type `MutexGuard<'_, usize>`
+   |
+help: `+=` can be used on `usize`, you can dereference `y`
+   |
+LL |     *y += 1;
+   |     +
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0070, E0308, E0368.
+For more information about an error, try `rustc --explain E0070`.
diff --git a/src/test/ui/typeck/assign-non-lval-mut-ref.fixed b/src/test/ui/typeck/assign-non-lval-mut-ref.fixed
new file mode 100644
index 000000000..10c7b9dbf
--- /dev/null
+++ b/src/test/ui/typeck/assign-non-lval-mut-ref.fixed
@@ -0,0 +1,15 @@
+// run-rustfix
+
+fn main() {
+    let mut x = vec![1usize];
+    *x.last_mut().unwrap() = 2;
+    //~^ ERROR invalid left-hand side of assignment
+    *x.last_mut().unwrap() += 1;
+    //~^ ERROR binary assignment operation `+=` cannot be applied to type `&mut usize`
+
+    let y = x.last_mut().unwrap();
+    *y = 2;
+    //~^ ERROR mismatched types
+    *y += 1;
+    //~^ ERROR binary assignment operation `+=` cannot be applied to type `&mut usize`
+}
diff --git a/src/test/ui/typeck/assign-non-lval-mut-ref.rs b/src/test/ui/typeck/assign-non-lval-mut-ref.rs
new file mode 100644
index 000000000..bceff0ef0
--- /dev/null
+++ b/src/test/ui/typeck/assign-non-lval-mut-ref.rs
@@ -0,0 +1,15 @@
+// run-rustfix
+
+fn main() {
+    let mut x = vec![1usize];
+    x.last_mut().unwrap() = 2;
+    //~^ ERROR invalid left-hand side of assignment
+    x.last_mut().unwrap() += 1;
+    //~^ ERROR binary assignment operation `+=` cannot be applied to type `&mut usize`
+
+    let y = x.last_mut().unwrap();
+    y = 2;
+    //~^ ERROR mismatched types
+    y += 1;
+    //~^ ERROR binary assignment operation `+=` cannot be applied to type `&mut usize`
+}
diff --git a/src/test/ui/typeck/assign-non-lval-mut-ref.stderr b/src/test/ui/typeck/assign-non-lval-mut-ref.stderr
new file mode 100644
index 000000000..be2e9fe95
--- /dev/null
+++ b/src/test/ui/typeck/assign-non-lval-mut-ref.stderr
@@ -0,0 +1,56 @@
+error[E0070]: invalid left-hand side of assignment
+  --> $DIR/assign-non-lval-mut-ref.rs:5:27
+   |
+LL |     x.last_mut().unwrap() = 2;
+   |     --------------------- ^
+   |     |
+   |     cannot assign to this expression
+   |
+help: consider dereferencing here to assign to the mutably borrowed value
+   |
+LL |     *x.last_mut().unwrap() = 2;
+   |     +
+
+error[E0368]: binary assignment operation `+=` cannot be applied to type `&mut usize`
+  --> $DIR/assign-non-lval-mut-ref.rs:7:5
+   |
+LL |     x.last_mut().unwrap() += 1;
+   |     ---------------------^^^^^
+   |     |
+   |     cannot use `+=` on type `&mut usize`
+   |
+help: `+=` can be used on `usize`, you can dereference `x.last_mut().unwrap()`
+   |
+LL |     *x.last_mut().unwrap() += 1;
+   |     +
+
+error[E0308]: mismatched types
+  --> $DIR/assign-non-lval-mut-ref.rs:11:9
+   |
+LL |     let y = x.last_mut().unwrap();
+   |             --------------------- expected due to this value
+LL |     y = 2;
+   |         ^ expected `&mut usize`, found integer
+   |
+help: consider dereferencing here to assign to the mutably borrowed value
+   |
+LL |     *y = 2;
+   |     +
+
+error[E0368]: binary assignment operation `+=` cannot be applied to type `&mut usize`
+  --> $DIR/assign-non-lval-mut-ref.rs:13:5
+   |
+LL |     y += 1;
+   |     -^^^^^
+   |     |
+   |     cannot use `+=` on type `&mut usize`
+   |
+help: `+=` can be used on `usize`, you can dereference `y`
+   |
+LL |     *y += 1;
+   |     +
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0070, E0308, E0368.
+For more information about an error, try `rustc --explain E0070`.
diff --git a/src/test/ui/typeck/autoderef-with-param-env-error.rs b/src/test/ui/typeck/autoderef-with-param-env-error.rs
new file mode 100644
index 000000000..ec96c61c6
--- /dev/null
+++ b/src/test/ui/typeck/autoderef-with-param-env-error.rs
@@ -0,0 +1,9 @@
+fn foo()
+where
+    T: Send,
+    //~^ cannot find type `T` in this scope
+{
+    let s = "abc".to_string();
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/autoderef-with-param-env-error.stderr b/src/test/ui/typeck/autoderef-with-param-env-error.stderr
new file mode 100644
index 000000000..cde800336
--- /dev/null
+++ b/src/test/ui/typeck/autoderef-with-param-env-error.stderr
@@ -0,0 +1,12 @@
+error[E0412]: cannot find type `T` in this scope
+  --> $DIR/autoderef-with-param-env-error.rs:3:5
+   |
+LL | fn foo()
+   |       - help: you might be missing a type parameter: `<T>`
+LL | where
+LL |     T: Send,
+   |     ^ not found in this scope
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0412`.
diff --git a/src/test/ui/typeck/auxiliary/issue-36708.rs b/src/test/ui/typeck/auxiliary/issue-36708.rs
new file mode 100644
index 000000000..bd8580f97
--- /dev/null
+++ b/src/test/ui/typeck/auxiliary/issue-36708.rs
@@ -0,0 +1,5 @@
+#![crate_type = "lib"]
+
+pub trait Foo {
+    fn foo();
+}
diff --git a/src/test/ui/typeck/auxiliary/issue-81943-lib.rs b/src/test/ui/typeck/auxiliary/issue-81943-lib.rs
new file mode 100644
index 000000000..521c54f89
--- /dev/null
+++ b/src/test/ui/typeck/auxiliary/issue-81943-lib.rs
@@ -0,0 +1,7 @@
+pub fn g(t: i32) -> i32 { t }
+// This function imitates `dbg!` so that future changes
+// to its macro definition won't make this test a dud.
+#[macro_export]
+macro_rules! d {
+  ($e:expr) => { match $e { x => { $crate::g(x) } } }
+}
diff --git a/src/test/ui/typeck/auxiliary/tdticc_coherence_lib.rs b/src/test/ui/typeck/auxiliary/tdticc_coherence_lib.rs
new file mode 100644
index 000000000..ef2cd415f
--- /dev/null
+++ b/src/test/ui/typeck/auxiliary/tdticc_coherence_lib.rs
@@ -0,0 +1,6 @@
+#![feature(auto_traits, core)]
+#![crate_type = "rlib"]
+
+pub auto trait DefaultedTrait { }
+
+pub struct Something<T> { t: T }
diff --git a/src/test/ui/typeck/auxiliary/xcrate-issue-43189-a.rs b/src/test/ui/typeck/auxiliary/xcrate-issue-43189-a.rs
new file mode 100644
index 000000000..9ab570fd1
--- /dev/null
+++ b/src/test/ui/typeck/auxiliary/xcrate-issue-43189-a.rs
@@ -0,0 +1,7 @@
+#![crate_type="lib"]
+
+
+pub trait A {
+    fn a(&self) {}
+}
+impl A for () {}
diff --git a/src/test/ui/typeck/auxiliary/xcrate-issue-43189-b.rs b/src/test/ui/typeck/auxiliary/xcrate-issue-43189-b.rs
new file mode 100644
index 000000000..31dfb050b
--- /dev/null
+++ b/src/test/ui/typeck/auxiliary/xcrate-issue-43189-b.rs
@@ -0,0 +1,3 @@
+#![crate_type="lib"]
+
+pub extern crate xcrate_issue_43189_a;
diff --git a/src/test/ui/typeck/auxiliary/xcrate-issue-46112-rexport-core.rs b/src/test/ui/typeck/auxiliary/xcrate-issue-46112-rexport-core.rs
new file mode 100644
index 000000000..2b517b578
--- /dev/null
+++ b/src/test/ui/typeck/auxiliary/xcrate-issue-46112-rexport-core.rs
@@ -0,0 +1,3 @@
+#![crate_type="lib"]
+
+pub extern crate core;
diff --git a/src/test/ui/typeck/auxiliary/xcrate-issue-61711-b.rs b/src/test/ui/typeck/auxiliary/xcrate-issue-61711-b.rs
new file mode 100644
index 000000000..88a040529
--- /dev/null
+++ b/src/test/ui/typeck/auxiliary/xcrate-issue-61711-b.rs
@@ -0,0 +1,5 @@
+// edition:2018
+#![crate_type="lib"]
+#![crate_name="xcrate_issue_61711_b"]
+pub struct Struct;
+pub use crate as alias;
diff --git a/src/test/ui/typeck/call-block.rs b/src/test/ui/typeck/call-block.rs
new file mode 100644
index 000000000..0390d7db0
--- /dev/null
+++ b/src/test/ui/typeck/call-block.rs
@@ -0,0 +1,3 @@
+fn main() {
+    let _ = {42}(); //~ ERROR expected function, found `{integer}`
+}
diff --git a/src/test/ui/typeck/call-block.stderr b/src/test/ui/typeck/call-block.stderr
new file mode 100644
index 000000000..68984bc1c
--- /dev/null
+++ b/src/test/ui/typeck/call-block.stderr
@@ -0,0 +1,11 @@
+error[E0618]: expected function, found `{integer}`
+  --> $DIR/call-block.rs:2:13
+   |
+LL |     let _ = {42}();
+   |             ^^^^--
+   |             |
+   |             call expression requires function
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0618`.
diff --git a/src/test/ui/typeck/conversion-methods.rs b/src/test/ui/typeck/conversion-methods.rs
new file mode 100644
index 000000000..46c2e511f
--- /dev/null
+++ b/src/test/ui/typeck/conversion-methods.rs
@@ -0,0 +1,13 @@
+use std::path::{Path, PathBuf};
+
+
+fn main() {
+    let _tis_an_instants_play: String = "'Tis a fond Ambush—"; //~ ERROR mismatched types
+    let _just_to_make_bliss: PathBuf = Path::new("/ern/her/own/surprise");
+    //~^ ERROR mismatched types
+
+    let _but_should_the_play: String = 2; // Perhaps surprisingly, we suggest .to_string() here
+    //~^ ERROR mismatched types
+
+    let _prove_piercing_earnest: Vec<usize> = &[1, 2, 3]; //~ ERROR mismatched types
+}
diff --git a/src/test/ui/typeck/conversion-methods.stderr b/src/test/ui/typeck/conversion-methods.stderr
new file mode 100644
index 000000000..091502bdd
--- /dev/null
+++ b/src/test/ui/typeck/conversion-methods.stderr
@@ -0,0 +1,45 @@
+error[E0308]: mismatched types
+  --> $DIR/conversion-methods.rs:5:41
+   |
+LL |     let _tis_an_instants_play: String = "'Tis a fond Ambush—";
+   |                                ------   ^^^^^^^^^^^^^^^^^^^^^- help: try using a conversion method: `.to_string()`
+   |                                |        |
+   |                                |        expected struct `String`, found `&str`
+   |                                expected due to this
+
+error[E0308]: mismatched types
+  --> $DIR/conversion-methods.rs:6:40
+   |
+LL |     let _just_to_make_bliss: PathBuf = Path::new("/ern/her/own/surprise");
+   |                              -------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- help: try using a conversion method: `.to_path_buf()`
+   |                              |         |
+   |                              |         expected struct `PathBuf`, found `&Path`
+   |                              expected due to this
+
+error[E0308]: mismatched types
+  --> $DIR/conversion-methods.rs:9:40
+   |
+LL |     let _but_should_the_play: String = 2; // Perhaps surprisingly, we suggest .to_string() here
+   |                               ------   ^- help: try using a conversion method: `.to_string()`
+   |                               |        |
+   |                               |        expected struct `String`, found integer
+   |                               expected due to this
+
+error[E0308]: mismatched types
+  --> $DIR/conversion-methods.rs:12:47
+   |
+LL |     let _prove_piercing_earnest: Vec<usize> = &[1, 2, 3];
+   |                                  ----------   ^^^^^^^^^^ expected struct `Vec`, found `&[{integer}; 3]`
+   |                                  |
+   |                                  expected due to this
+   |
+   = note: expected struct `Vec<usize>`
+           found reference `&[{integer}; 3]`
+help: try using a conversion method
+   |
+LL |     let _prove_piercing_earnest: Vec<usize> = (&[1, 2, 3]).to_vec();
+   |                                               +          ++++++++++
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/deref-multi.rs b/src/test/ui/typeck/deref-multi.rs
new file mode 100644
index 000000000..3dc4771fe
--- /dev/null
+++ b/src/test/ui/typeck/deref-multi.rs
@@ -0,0 +1,26 @@
+fn a(x: &&i32) -> i32 {
+    x
+    //~^ ERROR mismatched types
+}
+
+fn a2(x: &&&&&i32) -> i32 {
+    x
+    //~^ ERROR mismatched types
+}
+
+fn b(x: &i32) -> i32 {
+    &x
+    //~^ ERROR mismatched types
+}
+
+fn c(x: Box<i32>) -> i32 {
+    &x
+    //~^ ERROR mismatched types
+}
+
+fn d(x: std::sync::Mutex<&i32>) -> i32 {
+    x.lock().unwrap()
+    //~^ ERROR mismatched types
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/deref-multi.stderr b/src/test/ui/typeck/deref-multi.stderr
new file mode 100644
index 000000000..bd6575c73
--- /dev/null
+++ b/src/test/ui/typeck/deref-multi.stderr
@@ -0,0 +1,72 @@
+error[E0308]: mismatched types
+  --> $DIR/deref-multi.rs:2:5
+   |
+LL | fn a(x: &&i32) -> i32 {
+   |                   --- expected `i32` because of return type
+LL |     x
+   |     ^ expected `i32`, found `&&i32`
+   |
+help: consider dereferencing the borrow
+   |
+LL |     **x
+   |     ++
+
+error[E0308]: mismatched types
+  --> $DIR/deref-multi.rs:7:5
+   |
+LL | fn a2(x: &&&&&i32) -> i32 {
+   |                       --- expected `i32` because of return type
+LL |     x
+   |     ^ expected `i32`, found `&&&&&i32`
+   |
+help: consider dereferencing the borrow
+   |
+LL |     *****x
+   |     +++++
+
+error[E0308]: mismatched types
+  --> $DIR/deref-multi.rs:12:5
+   |
+LL | fn b(x: &i32) -> i32 {
+   |                  --- expected `i32` because of return type
+LL |     &x
+   |     ^^ expected `i32`, found `&&i32`
+   |
+help: consider removing the `&` and dereferencing the borrow instead
+   |
+LL |     *x
+   |     ~
+
+error[E0308]: mismatched types
+  --> $DIR/deref-multi.rs:17:5
+   |
+LL | fn c(x: Box<i32>) -> i32 {
+   |                      --- expected `i32` because of return type
+LL |     &x
+   |     ^^ expected `i32`, found `&Box<i32>`
+   |
+   = note:   expected type `i32`
+           found reference `&Box<i32>`
+help: consider removing the `&` and dereferencing the borrow instead
+   |
+LL |     *x
+   |     ~
+
+error[E0308]: mismatched types
+  --> $DIR/deref-multi.rs:22:5
+   |
+LL | fn d(x: std::sync::Mutex<&i32>) -> i32 {
+   |                                    --- expected `i32` because of return type
+LL |     x.lock().unwrap()
+   |     ^^^^^^^^^^^^^^^^^ expected `i32`, found struct `MutexGuard`
+   |
+   = note: expected type `i32`
+            found struct `MutexGuard<'_, &i32>`
+help: consider dereferencing the type
+   |
+LL |     **x.lock().unwrap()
+   |     ++
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/do-not-suggest-adding-missing-zero-to-floating-point-number.rs b/src/test/ui/typeck/do-not-suggest-adding-missing-zero-to-floating-point-number.rs
new file mode 100644
index 000000000..501f4b6ef
--- /dev/null
+++ b/src/test/ui/typeck/do-not-suggest-adding-missing-zero-to-floating-point-number.rs
@@ -0,0 +1,21 @@
+macro_rules! num { () => { 1 } }
+
+fn main() {
+    let x = 1i32;
+    x.e10; //~ERROR `i32` is a primitive type and therefore doesn't have fields
+
+    let y = 1;
+    y.e10; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+
+    2u32.e10; //~ERROR `u32` is a primitive type and therefore doesn't have fields
+
+    num!().e10; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+
+    2.e10foo; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+
+    42._;
+    //~^ERROR expected identifier, found reserved identifier `_`
+    //~|ERROR `{integer}` is a primitive type and therefore doesn't have fields
+
+    42.a; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+}
diff --git a/src/test/ui/typeck/do-not-suggest-adding-missing-zero-to-floating-point-number.stderr b/src/test/ui/typeck/do-not-suggest-adding-missing-zero-to-floating-point-number.stderr
new file mode 100644
index 000000000..1ef1d4c28
--- /dev/null
+++ b/src/test/ui/typeck/do-not-suggest-adding-missing-zero-to-floating-point-number.stderr
@@ -0,0 +1,51 @@
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/do-not-suggest-adding-missing-zero-to-floating-point-number.rs:16:8
+   |
+LL |     42._;
+   |        ^ expected identifier, found reserved identifier
+
+error[E0610]: `i32` is a primitive type and therefore doesn't have fields
+  --> $DIR/do-not-suggest-adding-missing-zero-to-floating-point-number.rs:5:7
+   |
+LL |     x.e10;
+   |       ^^^
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/do-not-suggest-adding-missing-zero-to-floating-point-number.rs:8:7
+   |
+LL |     y.e10;
+   |       ^^^
+
+error[E0610]: `u32` is a primitive type and therefore doesn't have fields
+  --> $DIR/do-not-suggest-adding-missing-zero-to-floating-point-number.rs:10:10
+   |
+LL |     2u32.e10;
+   |          ^^^
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/do-not-suggest-adding-missing-zero-to-floating-point-number.rs:12:12
+   |
+LL |     num!().e10;
+   |            ^^^
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/do-not-suggest-adding-missing-zero-to-floating-point-number.rs:14:7
+   |
+LL |     2.e10foo;
+   |       ^^^^^^
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/do-not-suggest-adding-missing-zero-to-floating-point-number.rs:16:8
+   |
+LL |     42._;
+   |        ^
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/do-not-suggest-adding-missing-zero-to-floating-point-number.rs:20:8
+   |
+LL |     42.a;
+   |        ^
+
+error: aborting due to 8 previous errors
+
+For more information about this error, try `rustc --explain E0610`.
diff --git a/src/test/ui/typeck/explain_clone_autoref.rs b/src/test/ui/typeck/explain_clone_autoref.rs
new file mode 100644
index 000000000..9279e4c39
--- /dev/null
+++ b/src/test/ui/typeck/explain_clone_autoref.rs
@@ -0,0 +1,13 @@
+struct NotClone;
+
+fn main() {
+    clone_thing(&NotClone);
+}
+
+fn clone_thing(nc: &NotClone) -> NotClone {
+    //~^ NOTE expected `NotClone` because of return type
+    nc.clone()
+    //~^ ERROR mismatched type
+    //~| NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
+    //~| NOTE expected struct `NotClone`, found `&NotClone`
+}
diff --git a/src/test/ui/typeck/explain_clone_autoref.stderr b/src/test/ui/typeck/explain_clone_autoref.stderr
new file mode 100644
index 000000000..faac680ea
--- /dev/null
+++ b/src/test/ui/typeck/explain_clone_autoref.stderr
@@ -0,0 +1,18 @@
+error[E0308]: mismatched types
+  --> $DIR/explain_clone_autoref.rs:9:5
+   |
+LL | fn clone_thing(nc: &NotClone) -> NotClone {
+   |                                  -------- expected `NotClone` because of return type
+LL |
+LL |     nc.clone()
+   |     ^^^^^^^^^^ expected struct `NotClone`, found `&NotClone`
+   |
+note: `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
+  --> $DIR/explain_clone_autoref.rs:9:5
+   |
+LL |     nc.clone()
+   |     ^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-10401.rs b/src/test/ui/typeck/issue-10401.rs
new file mode 100644
index 000000000..d77ff381e
--- /dev/null
+++ b/src/test/ui/typeck/issue-10401.rs
@@ -0,0 +1,5 @@
+fn main() {
+    let mut a = "a";
+    a += { "b" };
+    //~^ ERROR: binary assignment operation `+=` cannot be applied
+}
diff --git a/src/test/ui/typeck/issue-10401.stderr b/src/test/ui/typeck/issue-10401.stderr
new file mode 100644
index 000000000..1f68abcfb
--- /dev/null
+++ b/src/test/ui/typeck/issue-10401.stderr
@@ -0,0 +1,11 @@
+error[E0368]: binary assignment operation `+=` cannot be applied to type `&str`
+  --> $DIR/issue-10401.rs:3:5
+   |
+LL |     a += { "b" };
+   |     -^^^^^^^^^^^
+   |     |
+   |     cannot use `+=` on type `&str`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0368`.
diff --git a/src/test/ui/typeck/issue-13853-2.rs b/src/test/ui/typeck/issue-13853-2.rs
new file mode 100644
index 000000000..27319c98d
--- /dev/null
+++ b/src/test/ui/typeck/issue-13853-2.rs
@@ -0,0 +1,6 @@
+trait FromStructReader<'a> { }
+trait ResponseHook {
+     fn get(&self);
+}
+fn foo(res : Box<dyn ResponseHook>) { res.get } //~ ERROR attempted to take value of method
+fn main() {}
diff --git a/src/test/ui/typeck/issue-13853-2.stderr b/src/test/ui/typeck/issue-13853-2.stderr
new file mode 100644
index 000000000..92068df6c
--- /dev/null
+++ b/src/test/ui/typeck/issue-13853-2.stderr
@@ -0,0 +1,14 @@
+error[E0615]: attempted to take value of method `get` on type `Box<(dyn ResponseHook + 'static)>`
+  --> $DIR/issue-13853-2.rs:5:43
+   |
+LL | fn foo(res : Box<dyn ResponseHook>) { res.get }
+   |                                           ^^^ method, not a field
+   |
+help: use parentheses to call the method
+   |
+LL | fn foo(res : Box<dyn ResponseHook>) { res.get() }
+   |                                              ++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0615`.
diff --git a/src/test/ui/typeck/issue-13853-5.rs b/src/test/ui/typeck/issue-13853-5.rs
new file mode 100644
index 000000000..2afdf95aa
--- /dev/null
+++ b/src/test/ui/typeck/issue-13853-5.rs
@@ -0,0 +1,13 @@
+trait Deserializer<'a> { }
+
+trait Deserializable {
+    fn deserialize_token<'a, D: Deserializer<'a>>(_: D, _: &'a str) -> Self;
+}
+
+impl<'a, T: Deserializable> Deserializable for &'a str {
+    //~^ ERROR type parameter `T` is not constrained
+    fn deserialize_token<D: Deserializer<'a>>(_x: D, _y: &'a str) -> &'a str {
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-13853-5.stderr b/src/test/ui/typeck/issue-13853-5.stderr
new file mode 100644
index 000000000..3d8f824ec
--- /dev/null
+++ b/src/test/ui/typeck/issue-13853-5.stderr
@@ -0,0 +1,9 @@
+error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/issue-13853-5.rs:7:10
+   |
+LL | impl<'a, T: Deserializable> Deserializable for &'a str {
+   |          ^ unconstrained type parameter
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0207`.
diff --git a/src/test/ui/typeck/issue-13853.rs b/src/test/ui/typeck/issue-13853.rs
new file mode 100644
index 000000000..ac9886d2e
--- /dev/null
+++ b/src/test/ui/typeck/issue-13853.rs
@@ -0,0 +1,38 @@
+trait Node {
+    fn zomg();
+}
+
+trait Graph<N: Node> {
+    fn nodes<'a, I: Iterator<Item=&'a N>>(&'a self) -> I
+        where N: 'a;
+}
+
+impl<N: Node> Graph<N> for Vec<N> {
+    fn nodes<'a, I: Iterator<Item=&'a N>>(&self) -> I
+        where N: 'a
+    {
+        self.iter() //~ ERROR mismatched types
+    }
+}
+
+struct Stuff;
+
+impl Node for Stuff {
+    fn zomg() {
+        println!("zomg");
+    }
+}
+
+fn iterate<N: Node, G: Graph<N>>(graph: &G) {
+    for node in graph.iter() { //~ ERROR no method named `iter` found
+        node.zomg();
+    }
+}
+
+pub fn main() {
+    let graph = Vec::new();
+
+    graph.push(Stuff);
+
+    iterate(graph); //~ ERROR mismatched types
+}
diff --git a/src/test/ui/typeck/issue-13853.stderr b/src/test/ui/typeck/issue-13853.stderr
new file mode 100644
index 000000000..657bda5f6
--- /dev/null
+++ b/src/test/ui/typeck/issue-13853.stderr
@@ -0,0 +1,40 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-13853.rs:14:9
+   |
+LL |     fn nodes<'a, I: Iterator<Item=&'a N>>(&self) -> I
+   |                  - this type parameter              - expected `I` because of return type
+...
+LL |         self.iter()
+   |         ^^^^^^^^^^^ expected type parameter `I`, found struct `std::slice::Iter`
+   |
+   = note: expected type parameter `I`
+                      found struct `std::slice::Iter<'_, N>`
+
+error[E0599]: no method named `iter` found for reference `&G` in the current scope
+  --> $DIR/issue-13853.rs:27:23
+   |
+LL |     for node in graph.iter() {
+   |                       ^^^^ method not found in `&G`
+
+error[E0308]: mismatched types
+  --> $DIR/issue-13853.rs:37:13
+   |
+LL |     iterate(graph);
+   |     ------- ^^^^^
+   |     |       |
+   |     |       expected reference, found struct `Vec`
+   |     |       help: consider borrowing here: `&graph`
+   |     arguments to this function are incorrect
+   |
+   = note: expected reference `&_`
+                 found struct `Vec<Stuff>`
+note: function defined here
+  --> $DIR/issue-13853.rs:26:4
+   |
+LL | fn iterate<N: Node, G: Graph<N>>(graph: &G) {
+   |    ^^^^^^^                       ---------
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0308, E0599.
+For more information about an error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-29124.rs b/src/test/ui/typeck/issue-29124.rs
new file mode 100644
index 000000000..dd2784841
--- /dev/null
+++ b/src/test/ui/typeck/issue-29124.rs
@@ -0,0 +1,19 @@
+struct Ret;
+struct Obj;
+
+impl Obj {
+    fn func() -> Ret {
+        Ret
+    }
+}
+
+fn func() -> Ret {
+    Ret
+}
+
+fn main() {
+    Obj::func.x();
+    //~^ ERROR no method named `x` found
+    func.x();
+    //~^ ERROR no method named `x` found
+}
diff --git a/src/test/ui/typeck/issue-29124.stderr b/src/test/ui/typeck/issue-29124.stderr
new file mode 100644
index 000000000..c5d2ec084
--- /dev/null
+++ b/src/test/ui/typeck/issue-29124.stderr
@@ -0,0 +1,19 @@
+error[E0599]: no method named `x` found for fn item `fn() -> Ret {Obj::func}` in the current scope
+  --> $DIR/issue-29124.rs:15:15
+   |
+LL |     Obj::func.x();
+   |     --------- ^ method not found in `fn() -> Ret {Obj::func}`
+   |     |
+   |     this is a function, perhaps you wish to call it
+
+error[E0599]: no method named `x` found for fn item `fn() -> Ret {func}` in the current scope
+  --> $DIR/issue-29124.rs:17:10
+   |
+LL |     func.x();
+   |     ---- ^ method not found in `fn() -> Ret {func}`
+   |     |
+   |     this is a function, perhaps you wish to call it
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0599`.
diff --git a/src/test/ui/typeck/issue-36708.rs b/src/test/ui/typeck/issue-36708.rs
new file mode 100644
index 000000000..c9d9f2a6d
--- /dev/null
+++ b/src/test/ui/typeck/issue-36708.rs
@@ -0,0 +1,12 @@
+// aux-build:issue-36708.rs
+
+extern crate issue_36708 as lib;
+
+struct Bar;
+
+impl lib::Foo for Bar {
+    fn foo<T>() {}
+    //~^ ERROR E0049
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-36708.stderr b/src/test/ui/typeck/issue-36708.stderr
new file mode 100644
index 000000000..140f19f1f
--- /dev/null
+++ b/src/test/ui/typeck/issue-36708.stderr
@@ -0,0 +1,9 @@
+error[E0049]: method `foo` has 1 type parameter but its trait declaration has 0 type parameters
+  --> $DIR/issue-36708.rs:8:12
+   |
+LL |     fn foo<T>() {}
+   |            ^ found 1 type parameter, expected 0
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0049`.
diff --git a/src/test/ui/typeck/issue-43189.rs b/src/test/ui/typeck/issue-43189.rs
new file mode 100644
index 000000000..ce667a500
--- /dev/null
+++ b/src/test/ui/typeck/issue-43189.rs
@@ -0,0 +1,12 @@
+// Issue 46112: An extern crate pub re-exporting libcore was causing
+// paths rooted from `std` to be misrendered in the diagnostic output.
+
+// ignore-windows
+// aux-build:xcrate-issue-43189-a.rs
+// aux-build:xcrate-issue-43189-b.rs
+
+extern crate xcrate_issue_43189_b;
+fn main() {
+    ().a();
+    //~^ ERROR no method named `a` found
+}
diff --git a/src/test/ui/typeck/issue-43189.stderr b/src/test/ui/typeck/issue-43189.stderr
new file mode 100644
index 000000000..caf7530b8
--- /dev/null
+++ b/src/test/ui/typeck/issue-43189.stderr
@@ -0,0 +1,20 @@
+error[E0599]: no method named `a` found for unit type `()` in the current scope
+  --> $DIR/issue-43189.rs:10:8
+   |
+LL |     ().a();
+   |        ^ method not found in `()`
+   |
+  ::: $DIR/auxiliary/xcrate-issue-43189-a.rs:5:8
+   |
+LL |     fn a(&self) {}
+   |        - the method is available for `()` here
+   |
+   = help: items from traits can only be used if the trait is in scope
+help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+   |
+LL | use xcrate_issue_43189_b::xcrate_issue_43189_a::A;
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.
diff --git a/src/test/ui/typeck/issue-46112.rs b/src/test/ui/typeck/issue-46112.rs
new file mode 100644
index 000000000..0cdd2c27f
--- /dev/null
+++ b/src/test/ui/typeck/issue-46112.rs
@@ -0,0 +1,10 @@
+// Issue 46112: An extern crate pub re-exporting libcore was causing
+// paths rooted from `std` to be misrendered in the diagnostic output.
+
+// ignore-windows
+// aux-build:xcrate-issue-46112-rexport-core.rs
+
+extern crate xcrate_issue_46112_rexport_core;
+fn test(r: Result<Option<()>, &'static str>) { }
+fn main() { test(Ok(())); }
+//~^ mismatched types
diff --git a/src/test/ui/typeck/issue-46112.stderr b/src/test/ui/typeck/issue-46112.stderr
new file mode 100644
index 000000000..91381e8ef
--- /dev/null
+++ b/src/test/ui/typeck/issue-46112.stderr
@@ -0,0 +1,23 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-46112.rs:9:21
+   |
+LL | fn main() { test(Ok(())); }
+   |                  -- ^^ expected enum `Option`, found `()`
+   |                  |
+   |                  arguments to this enum variant are incorrect
+   |
+   = note:   expected enum `Option<()>`
+           found unit type `()`
+note: tuple variant defined here
+  --> $SRC_DIR/core/src/result.rs:LL:COL
+   |
+LL |     Ok(#[stable(feature = "rust1", since = "1.0.0")] T),
+   |     ^^
+help: try wrapping the expression in `Some`
+   |
+LL | fn main() { test(Ok(Some(()))); }
+   |                     +++++  +
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-52082-type-param-shadows-existing-type.rs b/src/test/ui/typeck/issue-52082-type-param-shadows-existing-type.rs
new file mode 100644
index 000000000..7bf151514
--- /dev/null
+++ b/src/test/ui/typeck/issue-52082-type-param-shadows-existing-type.rs
@@ -0,0 +1,54 @@
+// Fix issue 52082: Confusing error if accidentally defining a type parameter with the same name as
+// an existing type
+//
+// To this end, make sure that when trying to retrieve a field of a (reference to) type parameter,
+// rustc points to the point where the parameter was defined.
+#[derive(Debug)]
+struct Point
+{
+    x: i32,
+    y: i32
+}
+
+impl Point
+{
+    fn add(a: &Point, b: &Point) -> Point
+    {
+        Point {x: a.x + b.x, y: a.y + b.y}
+    }
+}
+
+trait Eq
+{
+    fn equals_ref<T>(a: &T, b: &T) -> bool;
+    fn equals_val<T>(a: T, b: T) -> bool;
+}
+
+impl Eq for Point
+{
+    fn equals_ref<Point>(a: &Point, b: &Point) -> bool
+    {
+        a.x == b.x && a.y == b.y //~ ERROR no field `x` on type `&Point` [E0609]
+                                 //~|ERROR no field `x` on type `&Point` [E0609]
+                                 //~|ERROR no field `y` on type `&Point` [E0609]
+                                 //~|ERROR no field `y` on type `&Point` [E0609]
+    }
+
+    fn equals_val<Point>(a: Point, b: Point) -> bool
+    {
+        a.x == b.x && a.y == b.y //~ ERROR no field `x` on type `Point` [E0609]
+                                 //~|ERROR no field `x` on type `Point` [E0609]
+                                 //~|ERROR no field `y` on type `Point` [E0609]
+                                 //~|ERROR no field `y` on type `Point` [E0609]
+    }
+}
+
+fn main()
+{
+    let p1 = Point {x:  0, y: 10};
+    let p2 = Point {x: 20, y: 42};
+    println!("{:?}", Point::add(&p1, &p2));
+    println!("p1: {:?}, p2: {:?}", p1, p2);
+    println!("&p1 == &p2: {:?}", Point::equals_ref(&p1, &p2));
+    println!("p1 == p2: {:?}", Point::equals_val(p1, p2));
+}
diff --git a/src/test/ui/typeck/issue-52082-type-param-shadows-existing-type.stderr b/src/test/ui/typeck/issue-52082-type-param-shadows-existing-type.stderr
new file mode 100644
index 000000000..4be4c91df
--- /dev/null
+++ b/src/test/ui/typeck/issue-52082-type-param-shadows-existing-type.stderr
@@ -0,0 +1,75 @@
+error[E0609]: no field `x` on type `&Point`
+  --> $DIR/issue-52082-type-param-shadows-existing-type.rs:31:11
+   |
+LL |     fn equals_ref<Point>(a: &Point, b: &Point) -> bool
+   |                   ----- type parameter 'Point' declared here
+LL |     {
+LL |         a.x == b.x && a.y == b.y
+   |           ^
+
+error[E0609]: no field `x` on type `&Point`
+  --> $DIR/issue-52082-type-param-shadows-existing-type.rs:31:18
+   |
+LL |     fn equals_ref<Point>(a: &Point, b: &Point) -> bool
+   |                   ----- type parameter 'Point' declared here
+LL |     {
+LL |         a.x == b.x && a.y == b.y
+   |                  ^
+
+error[E0609]: no field `y` on type `&Point`
+  --> $DIR/issue-52082-type-param-shadows-existing-type.rs:31:25
+   |
+LL |     fn equals_ref<Point>(a: &Point, b: &Point) -> bool
+   |                   ----- type parameter 'Point' declared here
+LL |     {
+LL |         a.x == b.x && a.y == b.y
+   |                         ^
+
+error[E0609]: no field `y` on type `&Point`
+  --> $DIR/issue-52082-type-param-shadows-existing-type.rs:31:32
+   |
+LL |     fn equals_ref<Point>(a: &Point, b: &Point) -> bool
+   |                   ----- type parameter 'Point' declared here
+LL |     {
+LL |         a.x == b.x && a.y == b.y
+   |                                ^
+
+error[E0609]: no field `x` on type `Point`
+  --> $DIR/issue-52082-type-param-shadows-existing-type.rs:39:11
+   |
+LL |     fn equals_val<Point>(a: Point, b: Point) -> bool
+   |                   ----- type parameter 'Point' declared here
+LL |     {
+LL |         a.x == b.x && a.y == b.y
+   |           ^
+
+error[E0609]: no field `x` on type `Point`
+  --> $DIR/issue-52082-type-param-shadows-existing-type.rs:39:18
+   |
+LL |     fn equals_val<Point>(a: Point, b: Point) -> bool
+   |                   ----- type parameter 'Point' declared here
+LL |     {
+LL |         a.x == b.x && a.y == b.y
+   |                  ^
+
+error[E0609]: no field `y` on type `Point`
+  --> $DIR/issue-52082-type-param-shadows-existing-type.rs:39:25
+   |
+LL |     fn equals_val<Point>(a: Point, b: Point) -> bool
+   |                   ----- type parameter 'Point' declared here
+LL |     {
+LL |         a.x == b.x && a.y == b.y
+   |                         ^
+
+error[E0609]: no field `y` on type `Point`
+  --> $DIR/issue-52082-type-param-shadows-existing-type.rs:39:32
+   |
+LL |     fn equals_val<Point>(a: Point, b: Point) -> bool
+   |                   ----- type parameter 'Point' declared here
+LL |     {
+LL |         a.x == b.x && a.y == b.y
+   |                                ^
+
+error: aborting due to 8 previous errors
+
+For more information about this error, try `rustc --explain E0609`.
diff --git a/src/test/ui/typeck/issue-55810-must-typeck-match-pats-before-guards.rs b/src/test/ui/typeck/issue-55810-must-typeck-match-pats-before-guards.rs
new file mode 100644
index 000000000..23ea0ad61
--- /dev/null
+++ b/src/test/ui/typeck/issue-55810-must-typeck-match-pats-before-guards.rs
@@ -0,0 +1,23 @@
+// check-pass
+
+// rust-lang/rust#55810: types for a binding in a match arm can be
+// inferred from arms that come later in the match.
+
+struct S;
+
+impl S {
+    fn method(&self) -> bool {
+        unimplemented!()
+    }
+}
+
+fn get<T>() -> T {
+    unimplemented!()
+}
+
+fn main() {
+    match get() {
+        x if x.method() => {}
+        &S => {}
+    }
+}
diff --git a/src/test/ui/typeck/issue-57673-ice-on-deref-of-boxed-trait.rs b/src/test/ui/typeck/issue-57673-ice-on-deref-of-boxed-trait.rs
new file mode 100644
index 000000000..0a4e7da2b
--- /dev/null
+++ b/src/test/ui/typeck/issue-57673-ice-on-deref-of-boxed-trait.rs
@@ -0,0 +1,7 @@
+//extern crate has_assoc_type;
+
+//fn ice(x: Box<dyn has_assoc_type::Foo<Assoc=()>>) {
+fn ice(x: Box<dyn Iterator<Item=()>>) {
+    *x //~ ERROR mismatched types [E0308]
+}
+fn main() {}
diff --git a/src/test/ui/typeck/issue-57673-ice-on-deref-of-boxed-trait.stderr b/src/test/ui/typeck/issue-57673-ice-on-deref-of-boxed-trait.stderr
new file mode 100644
index 000000000..b92a6f2ec
--- /dev/null
+++ b/src/test/ui/typeck/issue-57673-ice-on-deref-of-boxed-trait.stderr
@@ -0,0 +1,14 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-57673-ice-on-deref-of-boxed-trait.rs:5:5
+   |
+LL | fn ice(x: Box<dyn Iterator<Item=()>>) {
+   |                                       - help: try adding a return type: `-> (dyn Iterator<Item = ()> + 'static)`
+LL |     *x
+   |     ^^ expected `()`, found trait object `dyn Iterator`
+   |
+   = note: expected unit type `()`
+           found trait object `(dyn Iterator<Item = ()> + 'static)`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-61711-once-caused-rustc-inf-loop.rs b/src/test/ui/typeck/issue-61711-once-caused-rustc-inf-loop.rs
new file mode 100644
index 000000000..de7d6a0d8
--- /dev/null
+++ b/src/test/ui/typeck/issue-61711-once-caused-rustc-inf-loop.rs
@@ -0,0 +1,11 @@
+// Issue 61711: A crate pub re-exporting `crate` was causing an
+// infinite loop.
+
+// edition:2018
+// aux-build:xcrate-issue-61711-b.rs
+// compile-flags:--extern xcrate_issue_61711_b
+
+// build-pass
+
+fn f<F: Fn(xcrate_issue_61711_b::Struct)>(_: F) { }
+fn main() { }
diff --git a/src/test/ui/typeck/issue-65611.rs b/src/test/ui/typeck/issue-65611.rs
new file mode 100644
index 000000000..764531149
--- /dev/null
+++ b/src/test/ui/typeck/issue-65611.rs
@@ -0,0 +1,63 @@
+use std::mem::MaybeUninit;
+use std::ops::Deref;
+
+pub unsafe trait Array {
+    /// The array’s element type
+    type Item;
+    #[doc(hidden)]
+    /// The smallest index type that indexes the array.
+    type Index: Index;
+    #[doc(hidden)]
+    fn as_ptr(&self) -> *const Self::Item;
+    #[doc(hidden)]
+    fn as_mut_ptr(&mut self) -> *mut Self::Item;
+    #[doc(hidden)]
+    fn capacity() -> usize;
+}
+
+pub trait Index : PartialEq + Copy {
+    fn to_usize(self) -> usize;
+    fn from(i: usize) -> Self;
+}
+
+impl Index for usize {
+    fn to_usize(self) -> usize { self }
+    fn from(val: usize) -> Self {
+        val
+    }
+}
+
+unsafe impl<T> Array for [T; 1] {
+    type Item = T;
+    type Index = usize;
+    fn as_ptr(&self) -> *const T { self as *const _ as *const _ }
+    fn as_mut_ptr(&mut self) -> *mut T { self as *mut _ as *mut _}
+    fn capacity() -> usize { 1 }
+}
+
+impl<A: Array> Deref for ArrayVec<A> {
+    type Target = [A::Item];
+    #[inline]
+    fn deref(&self) -> &[A::Item] {
+        panic!()
+    }
+}
+
+pub struct ArrayVec<A: Array> {
+    xs: MaybeUninit<A>,
+    len: usize,
+}
+
+impl<A: Array> ArrayVec<A> {
+    pub fn new() -> ArrayVec<A> {
+        panic!()
+    }
+}
+
+fn main() {
+    let mut buffer = ArrayVec::new();
+    let x = buffer.last().unwrap().0.clone();
+    //~^ ERROR type annotations needed
+    //~| ERROR no field `0` on type `&_`
+    buffer.reverse();
+}
diff --git a/src/test/ui/typeck/issue-65611.stderr b/src/test/ui/typeck/issue-65611.stderr
new file mode 100644
index 000000000..003c63079
--- /dev/null
+++ b/src/test/ui/typeck/issue-65611.stderr
@@ -0,0 +1,16 @@
+error[E0282]: type annotations needed
+  --> $DIR/issue-65611.rs:59:13
+   |
+LL |     let x = buffer.last().unwrap().0.clone();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for type parameter `T`
+
+error[E0609]: no field `0` on type `&_`
+  --> $DIR/issue-65611.rs:59:36
+   |
+LL |     let x = buffer.last().unwrap().0.clone();
+   |                                    ^
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0282, E0609.
+For more information about an error, try `rustc --explain E0282`.
diff --git a/src/test/ui/typeck/issue-67971.rs b/src/test/ui/typeck/issue-67971.rs
new file mode 100644
index 000000000..8bf725cb5
--- /dev/null
+++ b/src/test/ui/typeck/issue-67971.rs
@@ -0,0 +1,9 @@
+struct S {}
+
+fn foo(ctx: &mut S) -> String { //~ ERROR mismatched types
+    // Don't suggest to remove semicolon as it won't fix anything
+    ctx.sleep = 0;
+    //~^ ERROR no field `sleep` on type `&mut S`
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-67971.stderr b/src/test/ui/typeck/issue-67971.stderr
new file mode 100644
index 000000000..5d07f9cc7
--- /dev/null
+++ b/src/test/ui/typeck/issue-67971.stderr
@@ -0,0 +1,18 @@
+error[E0609]: no field `sleep` on type `&mut S`
+  --> $DIR/issue-67971.rs:5:9
+   |
+LL |     ctx.sleep = 0;
+   |         ^^^^^ unknown field
+
+error[E0308]: mismatched types
+  --> $DIR/issue-67971.rs:3:24
+   |
+LL | fn foo(ctx: &mut S) -> String {
+   |    ---                 ^^^^^^ expected struct `String`, found `()`
+   |    |
+   |    implicitly returns `()` as its body has no tail or `return` expression
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0308, E0609.
+For more information about an error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-68590-reborrow-through-derefmut.rs b/src/test/ui/typeck/issue-68590-reborrow-through-derefmut.rs
new file mode 100644
index 000000000..e4436260e
--- /dev/null
+++ b/src/test/ui/typeck/issue-68590-reborrow-through-derefmut.rs
@@ -0,0 +1,25 @@
+// check-pass
+
+// rust-lang/rust#68590: confusing diagnostics when reborrowing through DerefMut.
+
+use std::cell::RefCell;
+
+struct A;
+
+struct S<'a> {
+    a: &'a mut A,
+}
+
+fn take_a(_: &mut A) {}
+
+fn test<'a>(s: &RefCell<S<'a>>) {
+    let mut guard = s.borrow_mut();
+    take_a(guard.a);
+    let _s2 = S { a: guard.a };
+}
+
+fn main() {
+    let a = &mut A;
+    let s = RefCell::new(S { a });
+    test(&s);
+}
diff --git a/src/test/ui/typeck/issue-69378-ice-on-invalid-type-node-after-recovery.rs b/src/test/ui/typeck/issue-69378-ice-on-invalid-type-node-after-recovery.rs
new file mode 100644
index 000000000..571692a53
--- /dev/null
+++ b/src/test/ui/typeck/issue-69378-ice-on-invalid-type-node-after-recovery.rs
@@ -0,0 +1,9 @@
+// Regression test for #69378: no type for node after struct parse recovery
+
+struct Foo { 0: u8 } //~ ERROR expected identifier
+
+fn test(f: Foo) {
+    Foo{foo: 4, ..f};
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-69378-ice-on-invalid-type-node-after-recovery.stderr b/src/test/ui/typeck/issue-69378-ice-on-invalid-type-node-after-recovery.stderr
new file mode 100644
index 000000000..6bc9c8498
--- /dev/null
+++ b/src/test/ui/typeck/issue-69378-ice-on-invalid-type-node-after-recovery.stderr
@@ -0,0 +1,8 @@
+error: expected identifier, found `0`
+  --> $DIR/issue-69378-ice-on-invalid-type-node-after-recovery.rs:3:14
+   |
+LL | struct Foo { 0: u8 }
+   |              ^ expected identifier
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/typeck/issue-72225-call-fnmut-through-derefmut.rs b/src/test/ui/typeck/issue-72225-call-fnmut-through-derefmut.rs
new file mode 100644
index 000000000..3ea05389f
--- /dev/null
+++ b/src/test/ui/typeck/issue-72225-call-fnmut-through-derefmut.rs
@@ -0,0 +1,21 @@
+// check-pass
+
+// rust-lang/rust#72225: confusing diagnostics when calling FnMut through DerefMut.
+
+use std::cell::RefCell;
+
+struct S {
+    f: Box<dyn FnMut()>
+}
+
+fn test(s: &RefCell<S>) {
+    let mut guard = s.borrow_mut();
+    (guard.f)();
+}
+
+fn main() {
+    let s = RefCell::new(S {
+        f: Box::new(|| ())
+    });
+    test(&s);
+}
diff --git a/src/test/ui/typeck/issue-73592-borrow_mut-through-deref.fixed b/src/test/ui/typeck/issue-73592-borrow_mut-through-deref.fixed
new file mode 100644
index 000000000..7fdd618c2
--- /dev/null
+++ b/src/test/ui/typeck/issue-73592-borrow_mut-through-deref.fixed
@@ -0,0 +1,59 @@
+// check-pass
+// run-rustfix
+//
+// rust-lang/rust#73592: borrow_mut through Deref should work.
+//
+// Before #72280, when we see something like `&mut *rcvr.method()`, we
+// incorrectly requires `rcvr` to be type-checked as a mut place. While this
+// requirement is usually correct for smart pointers, it is overly restrictive
+// for types like `Mutex` or `RefCell` which can produce a guard that
+// implements `DerefMut` from `&self`.
+//
+// Making it more confusing, because we use Deref as the fallback when DerefMut
+// is implemented, we won't see an issue when the smart pointer does not
+// implement `DerefMut`. It only causes an issue when `rcvr` is obtained via a
+// type that implements both `Deref` or `DerefMut`.
+//
+// This bug is only discovered in #73592 after it is already fixed as a side-effect
+// of a refactoring made in #72280.
+
+#![warn(unused_mut)]
+
+use std::pin::Pin;
+use std::cell::RefCell;
+
+struct S(RefCell<()>);
+
+fn test_pin(s: Pin<&S>) {
+    // This works before #72280.
+    let _ = &mut *s.0.borrow_mut();
+}
+
+fn test_pin_mut(s: Pin<&mut S>) {
+    // This should compile but didn't before #72280.
+    let _ = &mut *s.0.borrow_mut();
+}
+
+fn test_vec(s: &Vec<RefCell<()>>) {
+    // This should compile but didn't before #72280.
+    let _ = &mut *s[0].borrow_mut();
+}
+
+fn test_mut_pin(s: Pin<&S>) {
+    //~^ WARN variable does not need to be mutable
+    let _ = &mut *s.0.borrow_mut();
+}
+
+fn test_mut_pin_mut(s: Pin<&mut S>) {
+    //~^ WARN variable does not need to be mutable
+    let _ = &mut *s.0.borrow_mut();
+}
+
+fn main() {
+    let mut s = S(RefCell::new(()));
+    test_pin(Pin::new(&s));
+    test_pin_mut(Pin::new(&mut s));
+    test_mut_pin(Pin::new(&s));
+    test_mut_pin_mut(Pin::new(&mut s));
+    test_vec(&vec![s.0]);
+}
diff --git a/src/test/ui/typeck/issue-73592-borrow_mut-through-deref.rs b/src/test/ui/typeck/issue-73592-borrow_mut-through-deref.rs
new file mode 100644
index 000000000..3b399e629
--- /dev/null
+++ b/src/test/ui/typeck/issue-73592-borrow_mut-through-deref.rs
@@ -0,0 +1,59 @@
+// check-pass
+// run-rustfix
+//
+// rust-lang/rust#73592: borrow_mut through Deref should work.
+//
+// Before #72280, when we see something like `&mut *rcvr.method()`, we
+// incorrectly requires `rcvr` to be type-checked as a mut place. While this
+// requirement is usually correct for smart pointers, it is overly restrictive
+// for types like `Mutex` or `RefCell` which can produce a guard that
+// implements `DerefMut` from `&self`.
+//
+// Making it more confusing, because we use Deref as the fallback when DerefMut
+// is implemented, we won't see an issue when the smart pointer does not
+// implement `DerefMut`. It only causes an issue when `rcvr` is obtained via a
+// type that implements both `Deref` or `DerefMut`.
+//
+// This bug is only discovered in #73592 after it is already fixed as a side-effect
+// of a refactoring made in #72280.
+
+#![warn(unused_mut)]
+
+use std::pin::Pin;
+use std::cell::RefCell;
+
+struct S(RefCell<()>);
+
+fn test_pin(s: Pin<&S>) {
+    // This works before #72280.
+    let _ = &mut *s.0.borrow_mut();
+}
+
+fn test_pin_mut(s: Pin<&mut S>) {
+    // This should compile but didn't before #72280.
+    let _ = &mut *s.0.borrow_mut();
+}
+
+fn test_vec(s: &Vec<RefCell<()>>) {
+    // This should compile but didn't before #72280.
+    let _ = &mut *s[0].borrow_mut();
+}
+
+fn test_mut_pin(mut s: Pin<&S>) {
+    //~^ WARN variable does not need to be mutable
+    let _ = &mut *s.0.borrow_mut();
+}
+
+fn test_mut_pin_mut(mut s: Pin<&mut S>) {
+    //~^ WARN variable does not need to be mutable
+    let _ = &mut *s.0.borrow_mut();
+}
+
+fn main() {
+    let mut s = S(RefCell::new(()));
+    test_pin(Pin::new(&s));
+    test_pin_mut(Pin::new(&mut s));
+    test_mut_pin(Pin::new(&s));
+    test_mut_pin_mut(Pin::new(&mut s));
+    test_vec(&vec![s.0]);
+}
diff --git a/src/test/ui/typeck/issue-73592-borrow_mut-through-deref.stderr b/src/test/ui/typeck/issue-73592-borrow_mut-through-deref.stderr
new file mode 100644
index 000000000..5f5f672c3
--- /dev/null
+++ b/src/test/ui/typeck/issue-73592-borrow_mut-through-deref.stderr
@@ -0,0 +1,24 @@
+warning: variable does not need to be mutable
+  --> $DIR/issue-73592-borrow_mut-through-deref.rs:42:17
+   |
+LL | fn test_mut_pin(mut s: Pin<&S>) {
+   |                 ----^
+   |                 |
+   |                 help: remove this `mut`
+   |
+note: the lint level is defined here
+  --> $DIR/issue-73592-borrow_mut-through-deref.rs:20:9
+   |
+LL | #![warn(unused_mut)]
+   |         ^^^^^^^^^^
+
+warning: variable does not need to be mutable
+  --> $DIR/issue-73592-borrow_mut-through-deref.rs:47:21
+   |
+LL | fn test_mut_pin_mut(mut s: Pin<&mut S>) {
+   |                     ----^
+   |                     |
+   |                     help: remove this `mut`
+
+warning: 2 warnings emitted
+
diff --git a/src/test/ui/typeck/issue-74086.rs b/src/test/ui/typeck/issue-74086.rs
new file mode 100644
index 000000000..9b7c0d7cc
--- /dev/null
+++ b/src/test/ui/typeck/issue-74086.rs
@@ -0,0 +1,5 @@
+fn main() {
+    static BUG: fn(_) -> u8 = |_| 8;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions [E0121]
+    //~| ERROR the placeholder `_` is not allowed within types on item signatures for static items
+}
diff --git a/src/test/ui/typeck/issue-74086.stderr b/src/test/ui/typeck/issue-74086.stderr
new file mode 100644
index 000000000..95ebf9a90
--- /dev/null
+++ b/src/test/ui/typeck/issue-74086.stderr
@@ -0,0 +1,15 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/issue-74086.rs:2:20
+   |
+LL |     static BUG: fn(_) -> u8 = |_| 8;
+   |                    ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static items
+  --> $DIR/issue-74086.rs:2:20
+   |
+LL |     static BUG: fn(_) -> u8 = |_| 8;
+   |                    ^ not allowed in type signatures
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/issue-74933.rs b/src/test/ui/typeck/issue-74933.rs
new file mode 100644
index 000000000..4b6c173b8
--- /dev/null
+++ b/src/test/ui/typeck/issue-74933.rs
@@ -0,0 +1,38 @@
+// check-pass
+//
+// rust-lang/rust#74933: Lifetime error when indexing with borrowed index
+
+use std::ops::{Index, IndexMut};
+
+struct S(V);
+struct K<'a>(&'a ());
+struct V;
+
+impl<'a> Index<&'a K<'a>> for S {
+    type Output = V;
+
+    fn index(&self, _: &'a K<'a>) -> &V {
+        &self.0
+    }
+}
+
+impl<'a> IndexMut<&'a K<'a>> for S {
+    fn index_mut(&mut self, _: &'a K<'a>) -> &mut V {
+        &mut self.0
+    }
+}
+
+impl V {
+    fn foo(&mut self) {}
+}
+
+fn test(s: &mut S, k: &K<'_>) {
+    s[k] = V;
+    s[k].foo();
+}
+
+fn main() {
+    let mut s = S(V);
+    let k = K(&());
+    test(&mut s, &k);
+}
diff --git a/src/test/ui/typeck/issue-75883.rs b/src/test/ui/typeck/issue-75883.rs
new file mode 100644
index 000000000..885acc482
--- /dev/null
+++ b/src/test/ui/typeck/issue-75883.rs
@@ -0,0 +1,22 @@
+// Regression test for #75883.
+
+pub struct UI {}
+
+impl UI {
+    pub fn run() -> Result<_> {
+        //~^ ERROR: this enum takes 2 generic arguments but 1 generic argument was supplied
+        //~| ERROR: the placeholder `_` is not allowed within types on item signatures for return types
+        let mut ui = UI {};
+        ui.interact();
+
+        unimplemented!();
+    }
+
+    pub fn interact(&mut self) -> Result<_> {
+        //~^ ERROR: this enum takes 2 generic arguments but 1 generic argument was supplied
+        //~| ERROR: the placeholder `_` is not allowed within types on item signatures for return types
+        unimplemented!();
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-75883.stderr b/src/test/ui/typeck/issue-75883.stderr
new file mode 100644
index 000000000..3861e0507
--- /dev/null
+++ b/src/test/ui/typeck/issue-75883.stderr
@@ -0,0 +1,52 @@
+error[E0107]: this enum takes 2 generic arguments but 1 generic argument was supplied
+  --> $DIR/issue-75883.rs:6:21
+   |
+LL |     pub fn run() -> Result<_> {
+   |                     ^^^^^^ - supplied 1 generic argument
+   |                     |
+   |                     expected 2 generic arguments
+   |
+note: enum defined here, with 2 generic parameters: `T`, `E`
+  --> $SRC_DIR/core/src/result.rs:LL:COL
+   |
+LL | pub enum Result<T, E> {
+   |          ^^^^^^ -  -
+help: add missing generic argument
+   |
+LL |     pub fn run() -> Result<_, E> {
+   |                             +++
+
+error[E0107]: this enum takes 2 generic arguments but 1 generic argument was supplied
+  --> $DIR/issue-75883.rs:15:35
+   |
+LL |     pub fn interact(&mut self) -> Result<_> {
+   |                                   ^^^^^^ - supplied 1 generic argument
+   |                                   |
+   |                                   expected 2 generic arguments
+   |
+note: enum defined here, with 2 generic parameters: `T`, `E`
+  --> $SRC_DIR/core/src/result.rs:LL:COL
+   |
+LL | pub enum Result<T, E> {
+   |          ^^^^^^ -  -
+help: add missing generic argument
+   |
+LL |     pub fn interact(&mut self) -> Result<_, E> {
+   |                                           +++
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/issue-75883.rs:15:42
+   |
+LL |     pub fn interact(&mut self) -> Result<_> {
+   |                                          ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/issue-75883.rs:6:28
+   |
+LL |     pub fn run() -> Result<_> {
+   |                            ^ not allowed in type signatures
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0107, E0121.
+For more information about an error, try `rustc --explain E0107`.
diff --git a/src/test/ui/typeck/issue-75889.rs b/src/test/ui/typeck/issue-75889.rs
new file mode 100644
index 000000000..84c067ed0
--- /dev/null
+++ b/src/test/ui/typeck/issue-75889.rs
@@ -0,0 +1,6 @@
+// Regression test for #75889.
+
+const FOO: dyn Fn() -> _ = ""; //~ ERROR E0121
+static BOO: dyn Fn() -> _ = ""; //~ ERROR E0121
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-75889.stderr b/src/test/ui/typeck/issue-75889.stderr
new file mode 100644
index 000000000..1438f481e
--- /dev/null
+++ b/src/test/ui/typeck/issue-75889.stderr
@@ -0,0 +1,15 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constant items
+  --> $DIR/issue-75889.rs:3:24
+   |
+LL | const FOO: dyn Fn() -> _ = "";
+   |                        ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static items
+  --> $DIR/issue-75889.rs:4:25
+   |
+LL | static BOO: dyn Fn() -> _ = "";
+   |                         ^ not allowed in type signatures
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/issue-79040.rs b/src/test/ui/typeck/issue-79040.rs
new file mode 100644
index 000000000..941612542
--- /dev/null
+++ b/src/test/ui/typeck/issue-79040.rs
@@ -0,0 +1,5 @@
+fn main() {
+    const FOO = "hello" + 1; //~ ERROR cannot add `{integer}` to `&str`
+    //~^ missing type for `const` item
+    println!("{}", FOO);
+}
diff --git a/src/test/ui/typeck/issue-79040.stderr b/src/test/ui/typeck/issue-79040.stderr
new file mode 100644
index 000000000..aec2e1ec9
--- /dev/null
+++ b/src/test/ui/typeck/issue-79040.stderr
@@ -0,0 +1,17 @@
+error[E0369]: cannot add `{integer}` to `&str`
+  --> $DIR/issue-79040.rs:2:25
+   |
+LL |     const FOO = "hello" + 1;
+   |                 ------- ^ - {integer}
+   |                 |
+   |                 &str
+
+error: missing type for `const` item
+  --> $DIR/issue-79040.rs:2:11
+   |
+LL |     const FOO = "hello" + 1;
+   |           ^^^ help: provide a type for the item: `FOO: <type>`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0369`.
diff --git a/src/test/ui/typeck/issue-80207-unsized-return.rs b/src/test/ui/typeck/issue-80207-unsized-return.rs
new file mode 100644
index 000000000..75430da14
--- /dev/null
+++ b/src/test/ui/typeck/issue-80207-unsized-return.rs
@@ -0,0 +1,20 @@
+// check-pass
+
+trait Foo {
+    fn do_stuff() -> Self;
+}
+
+trait Bar {
+    type Output;
+}
+
+impl<T> Foo for dyn Bar<Output = T>
+where
+    Self: Sized,
+{
+    fn do_stuff() -> Self {
+        todo!()
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-80779.rs b/src/test/ui/typeck/issue-80779.rs
new file mode 100644
index 000000000..1624f6b77
--- /dev/null
+++ b/src/test/ui/typeck/issue-80779.rs
@@ -0,0 +1,13 @@
+// Regression test for #80779.
+
+pub struct T<'a>(&'a str);
+
+pub fn f<'a>(val: T<'a>) -> _ {
+    //~^ ERROR: the placeholder `_` is not allowed within types on item signatures for return types
+    g(val)
+}
+
+pub fn g(_: T<'static>) -> _ {}
+//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for return types
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-80779.stderr b/src/test/ui/typeck/issue-80779.stderr
new file mode 100644
index 000000000..2261ba616
--- /dev/null
+++ b/src/test/ui/typeck/issue-80779.stderr
@@ -0,0 +1,21 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/issue-80779.rs:10:28
+   |
+LL | pub fn g(_: T<'static>) -> _ {}
+   |                            ^
+   |                            |
+   |                            not allowed in type signatures
+   |                            help: replace with the correct return type: `()`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/issue-80779.rs:5:29
+   |
+LL | pub fn f<'a>(val: T<'a>) -> _ {
+   |                             ^
+   |                             |
+   |                             not allowed in type signatures
+   |                             help: replace with the correct return type: `()`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/issue-81293.rs b/src/test/ui/typeck/issue-81293.rs
new file mode 100644
index 000000000..076b8c944
--- /dev/null
+++ b/src/test/ui/typeck/issue-81293.rs
@@ -0,0 +1,9 @@
+fn main() {
+    let a: u16;
+    let b: u16 = 42;
+    let c: usize = 5;
+
+    a = c + b * 5; //~ ERROR: mismatched types [E0308]
+                   //~| ERROR: mismatched types [E0308]
+                   //~| ERROR: cannot add `u16` to `usize` [E0277]
+}
diff --git a/src/test/ui/typeck/issue-81293.stderr b/src/test/ui/typeck/issue-81293.stderr
new file mode 100644
index 000000000..9658288ac
--- /dev/null
+++ b/src/test/ui/typeck/issue-81293.stderr
@@ -0,0 +1,37 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-81293.rs:6:13
+   |
+LL |     a = c + b * 5;
+   |             ^^^^^ expected `usize`, found `u16`
+
+error[E0308]: mismatched types
+  --> $DIR/issue-81293.rs:6:9
+   |
+LL |     let a: u16;
+   |            --- expected due to this type
+...
+LL |     a = c + b * 5;
+   |         ^^^^^^^^^ expected `u16`, found `usize`
+
+error[E0277]: cannot add `u16` to `usize`
+  --> $DIR/issue-81293.rs:6:11
+   |
+LL |     a = c + b * 5;
+   |           ^ no implementation for `usize + u16`
+   |
+   = help: the trait `Add<u16>` is not implemented for `usize`
+   = help: the following other types implement trait `Add<Rhs>`:
+             <&'a f32 as Add<f32>>
+             <&'a f64 as Add<f64>>
+             <&'a i128 as Add<i128>>
+             <&'a i16 as Add<i16>>
+             <&'a i32 as Add<i32>>
+             <&'a i64 as Add<i64>>
+             <&'a i8 as Add<i8>>
+             <&'a isize as Add<isize>>
+           and 48 others
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0277, E0308.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/typeck/issue-81885.rs b/src/test/ui/typeck/issue-81885.rs
new file mode 100644
index 000000000..fb3949478
--- /dev/null
+++ b/src/test/ui/typeck/issue-81885.rs
@@ -0,0 +1,9 @@
+const TEST4: fn() -> _ = 42;
+                  //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+                  //~| ERROR the placeholder `_` is not allowed within types on item signatures for constant items
+
+fn main() {
+    const TEST5: fn() -> _ = 42;
+                      //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+                      //~| ERROR the placeholder `_` is not allowed within types on item signatures for constant items
+}
diff --git a/src/test/ui/typeck/issue-81885.stderr b/src/test/ui/typeck/issue-81885.stderr
new file mode 100644
index 000000000..91c08bd82
--- /dev/null
+++ b/src/test/ui/typeck/issue-81885.stderr
@@ -0,0 +1,27 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/issue-81885.rs:1:22
+   |
+LL | const TEST4: fn() -> _ = 42;
+   |                      ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constant items
+  --> $DIR/issue-81885.rs:1:22
+   |
+LL | const TEST4: fn() -> _ = 42;
+   |                      ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/issue-81885.rs:6:26
+   |
+LL |     const TEST5: fn() -> _ = 42;
+   |                          ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constant items
+  --> $DIR/issue-81885.rs:6:26
+   |
+LL |     const TEST5: fn() -> _ = 42;
+   |                          ^ not allowed in type signatures
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/issue-81943.rs b/src/test/ui/typeck/issue-81943.rs
new file mode 100644
index 000000000..18f5970a3
--- /dev/null
+++ b/src/test/ui/typeck/issue-81943.rs
@@ -0,0 +1,13 @@
+// aux-build:issue-81943-lib.rs
+extern crate issue_81943_lib as lib;
+
+fn f<F: Fn(i32)>(f: F) { f(0); }
+fn g(t: i32) -> i32 { t }
+fn main() {
+  f(|x| lib::d!(x)); //~ERROR
+  f(|x| match x { tmp => { g(tmp) } }); //~ERROR
+  macro_rules! d {
+    ($e:expr) => { match $e { x => { g(x) } } } //~ERROR
+  }
+  f(|x| d!(x));
+}
diff --git a/src/test/ui/typeck/issue-81943.stderr b/src/test/ui/typeck/issue-81943.stderr
new file mode 100644
index 000000000..041ff1075
--- /dev/null
+++ b/src/test/ui/typeck/issue-81943.stderr
@@ -0,0 +1,51 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-81943.rs:7:9
+   |
+LL |   f(|x| lib::d!(x));
+   |         ^^^^^^^^^^ expected `()`, found `i32`
+   |
+   = note: this error originates in the macro `lib::d` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0308]: mismatched types
+  --> $DIR/issue-81943.rs:8:28
+   |
+LL |   f(|x| match x { tmp => { g(tmp) } });
+   |         -------------------^^^^^^----
+   |         |                  |
+   |         |                  expected `()`, found `i32`
+   |         expected this to be `()`
+   |
+help: consider using a semicolon here
+   |
+LL |   f(|x| match x { tmp => { g(tmp); } });
+   |                                  +
+help: consider using a semicolon here
+   |
+LL |   f(|x| match x { tmp => { g(tmp) } };);
+   |                                      +
+
+error[E0308]: mismatched types
+  --> $DIR/issue-81943.rs:10:38
+   |
+LL |     ($e:expr) => { match $e { x => { g(x) } } }
+   |                    ------------------^^^^----
+   |                    |                 |
+   |                    |                 expected `()`, found `i32`
+   |                    expected this to be `()`
+LL |   }
+LL |   f(|x| d!(x));
+   |         ----- in this macro invocation
+   |
+   = note: this error originates in the macro `d` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider using a semicolon here
+   |
+LL |     ($e:expr) => { match $e { x => { g(x); } } }
+   |                                          +
+help: consider using a semicolon here
+   |
+LL |     ($e:expr) => { match $e { x => { g(x) } }; }
+   |                                              +
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-82772.rs b/src/test/ui/typeck/issue-82772.rs
new file mode 100644
index 000000000..326273bfe
--- /dev/null
+++ b/src/test/ui/typeck/issue-82772.rs
@@ -0,0 +1,13 @@
+// edition:2018
+
+fn main() {
+    use a::ModPrivateStruct;
+    let Box { 0: _, .. }: Box<()>; //~ ERROR field `0` of
+    let Box { 1: _, .. }: Box<()>; //~ ERROR field `1` of
+    let ModPrivateStruct { 1: _, .. } = ModPrivateStruct::default(); //~ ERROR field `1` of
+}
+
+mod a {
+    #[derive(Default)]
+    pub struct ModPrivateStruct(u8, u8);
+}
diff --git a/src/test/ui/typeck/issue-82772.stderr b/src/test/ui/typeck/issue-82772.stderr
new file mode 100644
index 000000000..321143cb9
--- /dev/null
+++ b/src/test/ui/typeck/issue-82772.stderr
@@ -0,0 +1,21 @@
+error[E0451]: field `0` of struct `Box` is private
+  --> $DIR/issue-82772.rs:5:15
+   |
+LL |     let Box { 0: _, .. }: Box<()>;
+   |               ^^^^ private field
+
+error[E0451]: field `1` of struct `Box` is private
+  --> $DIR/issue-82772.rs:6:15
+   |
+LL |     let Box { 1: _, .. }: Box<()>;
+   |               ^^^^ private field
+
+error[E0451]: field `1` of struct `ModPrivateStruct` is private
+  --> $DIR/issue-82772.rs:7:28
+   |
+LL |     let ModPrivateStruct { 1: _, .. } = ModPrivateStruct::default();
+   |                            ^^^^ private field
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0451`.
diff --git a/src/test/ui/typeck/issue-83621-placeholder-static-in-extern.rs b/src/test/ui/typeck/issue-83621-placeholder-static-in-extern.rs
new file mode 100644
index 000000000..16ec2a546
--- /dev/null
+++ b/src/test/ui/typeck/issue-83621-placeholder-static-in-extern.rs
@@ -0,0 +1,7 @@
+// Regression test for #83621.
+
+extern "C" {
+    static x: _; //~ ERROR: [E0121]
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-83621-placeholder-static-in-extern.stderr b/src/test/ui/typeck/issue-83621-placeholder-static-in-extern.stderr
new file mode 100644
index 000000000..9376e8bcf
--- /dev/null
+++ b/src/test/ui/typeck/issue-83621-placeholder-static-in-extern.stderr
@@ -0,0 +1,9 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/issue-83621-placeholder-static-in-extern.rs:4:15
+   |
+LL |     static x: _;
+   |               ^ not allowed in type signatures
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/issue-83693.rs b/src/test/ui/typeck/issue-83693.rs
new file mode 100644
index 000000000..a42558220
--- /dev/null
+++ b/src/test/ui/typeck/issue-83693.rs
@@ -0,0 +1,19 @@
+// Regression test for the ICE described in #83693.
+
+#![feature(fn_traits)]
+#![crate_type="lib"]
+
+impl F {
+//~^ ERROR: cannot find type `F` in this scope [E0412]
+    fn call() {
+        <Self as Fn(&TestResult)>::call
+        //~^ ERROR: cannot find type `TestResult` in this scope [E0412]
+        //~| associated type bindings are not allowed here [E0229]
+    }
+}
+
+fn call() {
+    <x as Fn(&usize)>::call
+    //~^ ERROR: cannot find type `x` in this scope [E0412]
+    //~| ERROR: associated type bindings are not allowed here [E0229]
+}
diff --git a/src/test/ui/typeck/issue-83693.stderr b/src/test/ui/typeck/issue-83693.stderr
new file mode 100644
index 000000000..0d8bbf1ce
--- /dev/null
+++ b/src/test/ui/typeck/issue-83693.stderr
@@ -0,0 +1,39 @@
+error[E0412]: cannot find type `F` in this scope
+  --> $DIR/issue-83693.rs:6:6
+   |
+LL | impl F {
+   |      ^ help: a trait with a similar name exists: `Fn`
+   |
+  ::: $SRC_DIR/core/src/ops/function.rs:LL:COL
+   |
+LL | pub trait Fn<Args>: FnMut<Args> {
+   | ------------------------------- similarly named trait `Fn` defined here
+
+error[E0412]: cannot find type `TestResult` in this scope
+  --> $DIR/issue-83693.rs:9:22
+   |
+LL |         <Self as Fn(&TestResult)>::call
+   |                      ^^^^^^^^^^ not found in this scope
+
+error[E0412]: cannot find type `x` in this scope
+  --> $DIR/issue-83693.rs:16:6
+   |
+LL |     <x as Fn(&usize)>::call
+   |      ^ not found in this scope
+
+error[E0229]: associated type bindings are not allowed here
+  --> $DIR/issue-83693.rs:9:18
+   |
+LL |         <Self as Fn(&TestResult)>::call
+   |                  ^^^^^^^^^^^^^^^ associated type not allowed here
+
+error[E0229]: associated type bindings are not allowed here
+  --> $DIR/issue-83693.rs:16:11
+   |
+LL |     <x as Fn(&usize)>::call
+   |           ^^^^^^^^^^ associated type not allowed here
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0229, E0412.
+For more information about an error, try `rustc --explain E0229`.
diff --git a/src/test/ui/typeck/issue-84160.rs b/src/test/ui/typeck/issue-84160.rs
new file mode 100644
index 000000000..7b444df85
--- /dev/null
+++ b/src/test/ui/typeck/issue-84160.rs
@@ -0,0 +1,9 @@
+fn mismatched_types_with_reference(x: &u32) -> &u32 {
+    if false {
+        return x;
+    }
+    return "test";
+    //~^ERROR mismatched types
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-84160.stderr b/src/test/ui/typeck/issue-84160.stderr
new file mode 100644
index 000000000..24c188b3f
--- /dev/null
+++ b/src/test/ui/typeck/issue-84160.stderr
@@ -0,0 +1,15 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-84160.rs:5:12
+   |
+LL | fn mismatched_types_with_reference(x: &u32) -> &u32 {
+   |                                                ---- expected `&u32` because of return type
+...
+LL |     return "test";
+   |            ^^^^^^ expected `u32`, found `str`
+   |
+   = note: expected reference `&u32`
+              found reference `&'static str`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-84768.rs b/src/test/ui/typeck/issue-84768.rs
new file mode 100644
index 000000000..ffa92823b
--- /dev/null
+++ b/src/test/ui/typeck/issue-84768.rs
@@ -0,0 +1,10 @@
+// Regression test for the ICE described in #84768.
+
+#![feature(fn_traits)]
+#![crate_type="lib"]
+
+fn transform_mut<F>(f: F) where F: for<'b> FnOnce(&'b mut u8) {
+    <F as FnOnce(&mut u8)>::call_once(f, 1)
+    //~^ ERROR: associated type bindings are not allowed here [E0229]
+    //~| ERROR: mismatched types [E0308]
+}
diff --git a/src/test/ui/typeck/issue-84768.stderr b/src/test/ui/typeck/issue-84768.stderr
new file mode 100644
index 000000000..04dc0e365
--- /dev/null
+++ b/src/test/ui/typeck/issue-84768.stderr
@@ -0,0 +1,26 @@
+error[E0229]: associated type bindings are not allowed here
+  --> $DIR/issue-84768.rs:7:11
+   |
+LL |     <F as FnOnce(&mut u8)>::call_once(f, 1)
+   |           ^^^^^^^^^^^^^^^ associated type not allowed here
+
+error[E0308]: mismatched types
+  --> $DIR/issue-84768.rs:7:42
+   |
+LL |     <F as FnOnce(&mut u8)>::call_once(f, 1)
+   |     ---------------------------------    ^ expected tuple, found integer
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected tuple `(&mut u8,)`
+               found type `{integer}`
+note: associated function defined here
+  --> $SRC_DIR/core/src/ops/function.rs:LL:COL
+   |
+LL |     extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
+   |                           ^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0229, E0308.
+For more information about an error, try `rustc --explain E0229`.
diff --git a/src/test/ui/typeck/issue-84831.rs b/src/test/ui/typeck/issue-84831.rs
new file mode 100644
index 000000000..c646f7107
--- /dev/null
+++ b/src/test/ui/typeck/issue-84831.rs
@@ -0,0 +1,9 @@
+fn f() {
+    std::<0>; //~ ERROR expected value
+}
+fn j() {
+    std::<_ as _>; //~ ERROR expected value
+    //~^ ERROR expected one of `,` or `>`, found keyword `as`
+}
+
+fn main () {}
diff --git a/src/test/ui/typeck/issue-84831.stderr b/src/test/ui/typeck/issue-84831.stderr
new file mode 100644
index 000000000..461ccb142
--- /dev/null
+++ b/src/test/ui/typeck/issue-84831.stderr
@@ -0,0 +1,26 @@
+error: expected one of `,` or `>`, found keyword `as`
+  --> $DIR/issue-84831.rs:5:13
+   |
+LL |     std::<_ as _>;
+   |             ^^ expected one of `,` or `>`
+   |
+help: expressions must be enclosed in braces to be used as const generic arguments
+   |
+LL |     std::<{ _ as _ }>;
+   |           +        +
+
+error[E0423]: expected value, found crate `std`
+  --> $DIR/issue-84831.rs:2:5
+   |
+LL |     std::<0>;
+   |     ^^^^^^^^ not a value
+
+error[E0423]: expected value, found crate `std`
+  --> $DIR/issue-84831.rs:5:5
+   |
+LL |     std::<_ as _>;
+   |     ^^^^^^^^^^^^^ not a value
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0423`.
diff --git a/src/test/ui/typeck/issue-86721-return-expr-ice.rev1.stderr b/src/test/ui/typeck/issue-86721-return-expr-ice.rev1.stderr
new file mode 100644
index 000000000..b1111fcf1
--- /dev/null
+++ b/src/test/ui/typeck/issue-86721-return-expr-ice.rev1.stderr
@@ -0,0 +1,9 @@
+error[E0572]: return statement outside of function body
+  --> $DIR/issue-86721-return-expr-ice.rs:9:22
+   |
+LL |     const U: usize = return;
+   |                      ^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0572`.
diff --git a/src/test/ui/typeck/issue-86721-return-expr-ice.rev2.stderr b/src/test/ui/typeck/issue-86721-return-expr-ice.rev2.stderr
new file mode 100644
index 000000000..f489ae200
--- /dev/null
+++ b/src/test/ui/typeck/issue-86721-return-expr-ice.rev2.stderr
@@ -0,0 +1,9 @@
+error[E0572]: return statement outside of function body
+  --> $DIR/issue-86721-return-expr-ice.rs:15:20
+   |
+LL |     fn foo(a: [(); return]);
+   |                    ^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0572`.
diff --git a/src/test/ui/typeck/issue-86721-return-expr-ice.rs b/src/test/ui/typeck/issue-86721-return-expr-ice.rs
new file mode 100644
index 000000000..cd7135f18
--- /dev/null
+++ b/src/test/ui/typeck/issue-86721-return-expr-ice.rs
@@ -0,0 +1,17 @@
+// Regression test for the ICE described in #86721.
+
+// revisions: rev1 rev2
+#![cfg_attr(any(), rev1, rev2)]
+#![crate_type="lib"]
+
+#[cfg(any(rev1))]
+trait T {
+    const U: usize = return;
+    //[rev1]~^ ERROR: return statement outside of function body [E0572]
+}
+
+#[cfg(any(rev2))]
+trait T2 {
+    fn foo(a: [(); return]);
+    //[rev2]~^ ERROR: return statement outside of function body [E0572]
+}
diff --git a/src/test/ui/typeck/issue-87181/empty-tuple-method.rs b/src/test/ui/typeck/issue-87181/empty-tuple-method.rs
new file mode 100644
index 000000000..1875d8280
--- /dev/null
+++ b/src/test/ui/typeck/issue-87181/empty-tuple-method.rs
@@ -0,0 +1,14 @@
+struct Bar<T> {
+    bar: T
+}
+
+struct Foo();
+impl Foo {
+    fn foo() { }
+}
+
+fn main() {
+    let thing = Bar { bar: Foo };
+    thing.bar.foo();
+    //~^ ERROR no method named `foo` found for fn item `fn() -> Foo {Foo}` in the current scope [E0599]
+}
diff --git a/src/test/ui/typeck/issue-87181/empty-tuple-method.stderr b/src/test/ui/typeck/issue-87181/empty-tuple-method.stderr
new file mode 100644
index 000000000..6ed70b301
--- /dev/null
+++ b/src/test/ui/typeck/issue-87181/empty-tuple-method.stderr
@@ -0,0 +1,16 @@
+error[E0599]: no method named `foo` found for fn item `fn() -> Foo {Foo}` in the current scope
+  --> $DIR/empty-tuple-method.rs:12:15
+   |
+LL |     thing.bar.foo();
+   |     --------- ^^^ method not found in `fn() -> Foo {Foo}`
+   |     |
+   |     this is the constructor of a struct
+   |
+help: call the constructor
+   |
+LL |     (thing.bar)().foo();
+   |     +         +++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.
diff --git a/src/test/ui/typeck/issue-87181/enum-variant.rs b/src/test/ui/typeck/issue-87181/enum-variant.rs
new file mode 100644
index 000000000..3b926b90f
--- /dev/null
+++ b/src/test/ui/typeck/issue-87181/enum-variant.rs
@@ -0,0 +1,16 @@
+struct Bar<T> {
+    bar: T
+}
+
+enum Foo{
+    Tup()
+}
+impl Foo {
+    fn foo() { }
+}
+
+fn main() {
+    let thing = Bar { bar: Foo::Tup };
+    thing.bar.foo();
+    //~^ ERROR no method named `foo` found for fn item `fn() -> Foo {Foo::Tup}` in the current scope [E0599]
+}
diff --git a/src/test/ui/typeck/issue-87181/enum-variant.stderr b/src/test/ui/typeck/issue-87181/enum-variant.stderr
new file mode 100644
index 000000000..a3a818696
--- /dev/null
+++ b/src/test/ui/typeck/issue-87181/enum-variant.stderr
@@ -0,0 +1,16 @@
+error[E0599]: no method named `foo` found for fn item `fn() -> Foo {Foo::Tup}` in the current scope
+  --> $DIR/enum-variant.rs:14:15
+   |
+LL |     thing.bar.foo();
+   |     --------- ^^^ method not found in `fn() -> Foo {Foo::Tup}`
+   |     |
+   |     this is the constructor of an enum variant
+   |
+help: call the constructor
+   |
+LL |     (thing.bar)().foo();
+   |     +         +++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.
diff --git a/src/test/ui/typeck/issue-87181/tuple-field.rs b/src/test/ui/typeck/issue-87181/tuple-field.rs
new file mode 100644
index 000000000..00e3b460e
--- /dev/null
+++ b/src/test/ui/typeck/issue-87181/tuple-field.rs
@@ -0,0 +1,14 @@
+struct Bar<T> {
+    bar: T
+}
+
+struct Foo(char, u16);
+impl Foo {
+    fn foo() { }
+}
+
+fn main() {
+    let thing = Bar { bar: Foo };
+    thing.bar.0;
+    //~^ ERROR no field `0` on type `fn(char, u16) -> Foo {Foo}` [E0609]
+}
diff --git a/src/test/ui/typeck/issue-87181/tuple-field.stderr b/src/test/ui/typeck/issue-87181/tuple-field.stderr
new file mode 100644
index 000000000..4d22ada02
--- /dev/null
+++ b/src/test/ui/typeck/issue-87181/tuple-field.stderr
@@ -0,0 +1,16 @@
+error[E0609]: no field `0` on type `fn(char, u16) -> Foo {Foo}`
+  --> $DIR/tuple-field.rs:12:15
+   |
+LL |     thing.bar.0;
+   |     --------- ^
+   |     |
+   |     this is the constructor of a struct
+   |
+help: call the constructor
+   |
+LL |     (thing.bar)(_, _).0;
+   |     +         +++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0609`.
diff --git a/src/test/ui/typeck/issue-87181/tuple-method.rs b/src/test/ui/typeck/issue-87181/tuple-method.rs
new file mode 100644
index 000000000..e88f642b0
--- /dev/null
+++ b/src/test/ui/typeck/issue-87181/tuple-method.rs
@@ -0,0 +1,14 @@
+struct Bar<T> {
+    bar: T
+}
+
+struct Foo(u8, i32);
+impl Foo {
+    fn foo() { }
+}
+
+fn main() {
+    let thing = Bar { bar: Foo };
+    thing.bar.foo();
+    //~^ ERROR no method named `foo` found for fn item `fn(u8, i32) -> Foo {Foo}` in the current scope [E0599]
+}
diff --git a/src/test/ui/typeck/issue-87181/tuple-method.stderr b/src/test/ui/typeck/issue-87181/tuple-method.stderr
new file mode 100644
index 000000000..1e392e179
--- /dev/null
+++ b/src/test/ui/typeck/issue-87181/tuple-method.stderr
@@ -0,0 +1,16 @@
+error[E0599]: no method named `foo` found for fn item `fn(u8, i32) -> Foo {Foo}` in the current scope
+  --> $DIR/tuple-method.rs:12:15
+   |
+LL |     thing.bar.foo();
+   |     --------- ^^^ method not found in `fn(u8, i32) -> Foo {Foo}`
+   |     |
+   |     this is the constructor of a struct
+   |
+help: call the constructor
+   |
+LL |     (thing.bar)(_, _).foo();
+   |     +         +++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.
diff --git a/src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.rs b/src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.rs
new file mode 100644
index 000000000..751dc8719
--- /dev/null
+++ b/src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let mut a;
+    a = a = true; //~ ERROR mismatched types
+}
diff --git a/src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.stderr b/src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.stderr
new file mode 100644
index 000000000..56817ee2c
--- /dev/null
+++ b/src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.stderr
@@ -0,0 +1,11 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-87771-ice-assign-assign-to-bool.rs:3:9
+   |
+LL |     let mut a;
+   |         ----- expected due to the type of this binding
+LL |     a = a = true;
+   |         ^^^^^^^^ expected `bool`, found `()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-87872-missing-inaccessible-field-literal.rs b/src/test/ui/typeck/issue-87872-missing-inaccessible-field-literal.rs
new file mode 100644
index 000000000..326e958aa
--- /dev/null
+++ b/src/test/ui/typeck/issue-87872-missing-inaccessible-field-literal.rs
@@ -0,0 +1,11 @@
+pub mod foo {
+    pub struct Foo {
+        pub you_can_use_this_field: bool,
+        you_cant_use_this_field: bool,
+    }
+}
+
+fn main() {
+    foo::Foo {};
+    //~^ ERROR cannot construct `Foo` with struct literal syntax due to private fields
+}
diff --git a/src/test/ui/typeck/issue-87872-missing-inaccessible-field-literal.stderr b/src/test/ui/typeck/issue-87872-missing-inaccessible-field-literal.stderr
new file mode 100644
index 000000000..f0bd3e0dd
--- /dev/null
+++ b/src/test/ui/typeck/issue-87872-missing-inaccessible-field-literal.stderr
@@ -0,0 +1,10 @@
+error: cannot construct `Foo` with struct literal syntax due to private fields
+  --> $DIR/issue-87872-missing-inaccessible-field-literal.rs:9:5
+   |
+LL |     foo::Foo {};
+   |     ^^^^^^^^
+   |
+   = note: ... and other private field `you_cant_use_this_field` that was not provided
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/typeck/issue-87872-missing-inaccessible-field-pattern.rs b/src/test/ui/typeck/issue-87872-missing-inaccessible-field-pattern.rs
new file mode 100644
index 000000000..d28e17559
--- /dev/null
+++ b/src/test/ui/typeck/issue-87872-missing-inaccessible-field-pattern.rs
@@ -0,0 +1,11 @@
+#![allow(dead_code, unused_variables)]
+
+pub mod foo {
+    #[derive(Default)]
+    pub struct Foo { pub visible: bool, invisible: bool, }
+}
+
+fn main() {
+    let foo::Foo {} = foo::Foo::default();
+    //~^ ERROR pattern does not mention field `visible` and inaccessible fields
+}
diff --git a/src/test/ui/typeck/issue-87872-missing-inaccessible-field-pattern.stderr b/src/test/ui/typeck/issue-87872-missing-inaccessible-field-pattern.stderr
new file mode 100644
index 000000000..dc3097510
--- /dev/null
+++ b/src/test/ui/typeck/issue-87872-missing-inaccessible-field-pattern.stderr
@@ -0,0 +1,18 @@
+error[E0027]: pattern does not mention field `visible` and inaccessible fields
+  --> $DIR/issue-87872-missing-inaccessible-field-pattern.rs:9:9
+   |
+LL |     let foo::Foo {} = foo::Foo::default();
+   |         ^^^^^^^^^^^ missing field `visible` and inaccessible fields
+   |
+help: include the missing field in the pattern and ignore the inaccessible fields
+   |
+LL |     let foo::Foo { visible, .. } = foo::Foo::default();
+   |                  ~~~~~~~~~~~~~~~
+help: if you don't care about this missing field, you can explicitly ignore it
+   |
+LL |     let foo::Foo { .. } = foo::Foo::default();
+   |                  ~~~~~~
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0027`.
diff --git a/src/test/ui/typeck/issue-87935-unsized-box-expr.rs b/src/test/ui/typeck/issue-87935-unsized-box-expr.rs
new file mode 100644
index 000000000..cd2a82074
--- /dev/null
+++ b/src/test/ui/typeck/issue-87935-unsized-box-expr.rs
@@ -0,0 +1,10 @@
+#![feature(box_syntax)]
+// Box expression needs to be movable, and hence has to be of a Sized type.
+fn main() {
+    let _x: Box<[u32]> = box { loop {} };
+    //~^ ERROR: the size for values of type `[u32]` cannot be known at compilation time
+
+    // Check that a deduced size does not cause issues.
+    let _y: Box<[u32]> = box [];
+    let _z: Box<[u32; 0]> = box { loop {} };
+}
diff --git a/src/test/ui/typeck/issue-87935-unsized-box-expr.stderr b/src/test/ui/typeck/issue-87935-unsized-box-expr.stderr
new file mode 100644
index 000000000..9ff822352
--- /dev/null
+++ b/src/test/ui/typeck/issue-87935-unsized-box-expr.stderr
@@ -0,0 +1,12 @@
+error[E0277]: the size for values of type `[u32]` cannot be known at compilation time
+  --> $DIR/issue-87935-unsized-box-expr.rs:4:30
+   |
+LL |     let _x: Box<[u32]> = box { loop {} };
+   |                              ^^^^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `[u32]`
+   = note: the type of a box expression must have a statically known size
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/typeck/issue-88609.rs b/src/test/ui/typeck/issue-88609.rs
new file mode 100644
index 000000000..dc459c885
--- /dev/null
+++ b/src/test/ui/typeck/issue-88609.rs
@@ -0,0 +1,19 @@
+// Regression test for #88609:
+// The return type for `main` is not normalized while checking if it implements
+// the trait `std::process::Termination`.
+
+// build-pass
+
+trait Same {
+    type Output;
+}
+
+impl<T> Same for T {
+    type Output = T;
+}
+
+type Unit = <() as Same>::Output;
+
+fn main() -> Result<Unit, std::io::Error> {
+    unimplemented!()
+}
diff --git a/src/test/ui/typeck/issue-88643.rs b/src/test/ui/typeck/issue-88643.rs
new file mode 100644
index 000000000..4435cba02
--- /dev/null
+++ b/src/test/ui/typeck/issue-88643.rs
@@ -0,0 +1,19 @@
+// Regression test for the ICE described in #88643. Specifically:
+// https://github.com/rust-lang/rust/issues/88643#issuecomment-913128893
+// and https://github.com/rust-lang/rust/issues/88643#issuecomment-913171935
+// and https://github.com/rust-lang/rust/issues/88643#issuecomment-913765984
+
+use std::collections::HashMap;
+
+pub trait T {}
+
+static CALLBACKS: HashMap<*const dyn T, dyn FnMut(&mut _) + 'static> = HashMap::new();
+//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for static items [E0121]
+
+static CALLBACKS2: Vec<dyn Fn(& _)> = Vec::new();
+//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for static items [E0121]
+
+static CALLBACKS3: Option<dyn Fn(& _)> = None;
+//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for static items [E0121]
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-88643.stderr b/src/test/ui/typeck/issue-88643.stderr
new file mode 100644
index 000000000..d5d596b6f
--- /dev/null
+++ b/src/test/ui/typeck/issue-88643.stderr
@@ -0,0 +1,21 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static items
+  --> $DIR/issue-88643.rs:10:56
+   |
+LL | static CALLBACKS: HashMap<*const dyn T, dyn FnMut(&mut _) + 'static> = HashMap::new();
+   |                                                        ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static items
+  --> $DIR/issue-88643.rs:13:33
+   |
+LL | static CALLBACKS2: Vec<dyn Fn(& _)> = Vec::new();
+   |                                 ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static items
+  --> $DIR/issue-88643.rs:16:36
+   |
+LL | static CALLBACKS3: Option<dyn Fn(& _)> = None;
+   |                                    ^ not allowed in type signatures
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/issue-88803-call-expr-method.fixed b/src/test/ui/typeck/issue-88803-call-expr-method.fixed
new file mode 100644
index 000000000..19b96ecf3
--- /dev/null
+++ b/src/test/ui/typeck/issue-88803-call-expr-method.fixed
@@ -0,0 +1,9 @@
+// run-rustfix
+
+fn main() {
+    let a = Some(42);
+    println!(
+        "The value is {}.",
+        a.unwrap() //~ERROR [E0615]
+    );
+}
diff --git a/src/test/ui/typeck/issue-88803-call-expr-method.rs b/src/test/ui/typeck/issue-88803-call-expr-method.rs
new file mode 100644
index 000000000..a06199466
--- /dev/null
+++ b/src/test/ui/typeck/issue-88803-call-expr-method.rs
@@ -0,0 +1,9 @@
+// run-rustfix
+
+fn main() {
+    let a = Some(42);
+    println!(
+        "The value is {}.",
+        (a.unwrap)() //~ERROR [E0615]
+    );
+}
diff --git a/src/test/ui/typeck/issue-88803-call-expr-method.stderr b/src/test/ui/typeck/issue-88803-call-expr-method.stderr
new file mode 100644
index 000000000..645c04b87
--- /dev/null
+++ b/src/test/ui/typeck/issue-88803-call-expr-method.stderr
@@ -0,0 +1,15 @@
+error[E0615]: attempted to take value of method `unwrap` on type `Option<{integer}>`
+  --> $DIR/issue-88803-call-expr-method.rs:7:12
+   |
+LL |         (a.unwrap)()
+   |            ^^^^^^ method, not a field
+   |
+help: remove wrapping parentheses to call the method
+   |
+LL -         (a.unwrap)()
+LL +         a.unwrap()
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0615`.
diff --git a/src/test/ui/typeck/issue-88844.rs b/src/test/ui/typeck/issue-88844.rs
new file mode 100644
index 000000000..116c75aab
--- /dev/null
+++ b/src/test/ui/typeck/issue-88844.rs
@@ -0,0 +1,14 @@
+// Regression test for #88844.
+
+struct Struct { value: i32 }
+//~^ NOTE: similarly named struct `Struct` defined here
+
+impl Stuct {
+//~^ ERROR: cannot find type `Stuct` in this scope [E0412]
+//~| HELP: a struct with a similar name exists
+    fn new() -> Self {
+        Self { value: 42 }
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-88844.stderr b/src/test/ui/typeck/issue-88844.stderr
new file mode 100644
index 000000000..90bba90be
--- /dev/null
+++ b/src/test/ui/typeck/issue-88844.stderr
@@ -0,0 +1,12 @@
+error[E0412]: cannot find type `Stuct` in this scope
+  --> $DIR/issue-88844.rs:6:6
+   |
+LL | struct Struct { value: i32 }
+   | ------------- similarly named struct `Struct` defined here
+...
+LL | impl Stuct {
+   |      ^^^^^ help: a struct with a similar name exists: `Struct`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0412`.
diff --git a/src/test/ui/typeck/issue-89044-wrapped-expr-method.fixed b/src/test/ui/typeck/issue-89044-wrapped-expr-method.fixed
new file mode 100644
index 000000000..0a3086a34
--- /dev/null
+++ b/src/test/ui/typeck/issue-89044-wrapped-expr-method.fixed
@@ -0,0 +1,9 @@
+// run-rustfix
+
+fn main() {
+    let a = Some(42);
+    println!(
+        "The value is {}.",
+        (a.unwrap()) //~ERROR [E0615]
+    );
+}
diff --git a/src/test/ui/typeck/issue-89044-wrapped-expr-method.rs b/src/test/ui/typeck/issue-89044-wrapped-expr-method.rs
new file mode 100644
index 000000000..83617e035
--- /dev/null
+++ b/src/test/ui/typeck/issue-89044-wrapped-expr-method.rs
@@ -0,0 +1,9 @@
+// run-rustfix
+
+fn main() {
+    let a = Some(42);
+    println!(
+        "The value is {}.",
+        (a.unwrap) //~ERROR [E0615]
+    );
+}
diff --git a/src/test/ui/typeck/issue-89044-wrapped-expr-method.stderr b/src/test/ui/typeck/issue-89044-wrapped-expr-method.stderr
new file mode 100644
index 000000000..6fa0915dc
--- /dev/null
+++ b/src/test/ui/typeck/issue-89044-wrapped-expr-method.stderr
@@ -0,0 +1,14 @@
+error[E0615]: attempted to take value of method `unwrap` on type `Option<{integer}>`
+  --> $DIR/issue-89044-wrapped-expr-method.rs:7:12
+   |
+LL |         (a.unwrap)
+   |            ^^^^^^ method, not a field
+   |
+help: use parentheses to call the method
+   |
+LL |         (a.unwrap())
+   |                  ++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0615`.
diff --git a/src/test/ui/typeck/issue-89275.rs b/src/test/ui/typeck/issue-89275.rs
new file mode 100644
index 000000000..b91c00175
--- /dev/null
+++ b/src/test/ui/typeck/issue-89275.rs
@@ -0,0 +1,29 @@
+#![recursion_limit = "5"] // To reduce noise
+
+//expect mutability error when ambiguous traits are in scope
+//and not an overflow error on the span in the main function.
+
+struct Ratio<T>(T);
+
+pub trait Pow {
+    fn pow(self) -> Self;
+}
+
+impl<'a, T> Pow for &'a Ratio<T>
+where
+    &'a T: Pow,
+{
+    fn pow(self) -> Self {
+        self
+    }
+}
+
+fn downcast<'a, W: ?Sized>() -> &'a W {
+    todo!()
+}
+
+struct Other;
+
+fn main() {
+    let other: &mut Other = downcast();//~ERROR 28:29: 28:39: mismatched types [E0308]
+}
diff --git a/src/test/ui/typeck/issue-89275.stderr b/src/test/ui/typeck/issue-89275.stderr
new file mode 100644
index 000000000..d73e647d2
--- /dev/null
+++ b/src/test/ui/typeck/issue-89275.stderr
@@ -0,0 +1,14 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-89275.rs:28:29
+   |
+LL |     let other: &mut Other = downcast();
+   |                ----------   ^^^^^^^^^^ types differ in mutability
+   |                |
+   |                expected due to this
+   |
+   = note: expected mutable reference `&mut Other`
+                      found reference `&_`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-89806.rs b/src/test/ui/typeck/issue-89806.rs
new file mode 100644
index 000000000..69cec0865
--- /dev/null
+++ b/src/test/ui/typeck/issue-89806.rs
@@ -0,0 +1,3 @@
+fn main() {
+    0u8.as_ref(); //~ ERROR no method named `as_ref` found for type `u8` in the current scope
+}
diff --git a/src/test/ui/typeck/issue-89806.stderr b/src/test/ui/typeck/issue-89806.stderr
new file mode 100644
index 000000000..c36b4967e
--- /dev/null
+++ b/src/test/ui/typeck/issue-89806.stderr
@@ -0,0 +1,9 @@
+error[E0599]: no method named `as_ref` found for type `u8` in the current scope
+  --> $DIR/issue-89806.rs:2:9
+   |
+LL |     0u8.as_ref();
+   |         ^^^^^^ method not found in `u8`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.
diff --git a/src/test/ui/typeck/issue-89856.rs b/src/test/ui/typeck/issue-89856.rs
new file mode 100644
index 000000000..b021e349e
--- /dev/null
+++ b/src/test/ui/typeck/issue-89856.rs
@@ -0,0 +1,8 @@
+fn take_str_maybe(x: Option<&str>) -> Option<&str> { None }
+
+fn main() {
+    let string = String::from("Hello, world");
+    let option = Some(&string);
+    take_str_maybe(option);
+    //~^ ERROR: mismatched types [E0308]
+}
diff --git a/src/test/ui/typeck/issue-89856.stderr b/src/test/ui/typeck/issue-89856.stderr
new file mode 100644
index 000000000..5fa1ae1a5
--- /dev/null
+++ b/src/test/ui/typeck/issue-89856.stderr
@@ -0,0 +1,23 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-89856.rs:6:20
+   |
+LL |     take_str_maybe(option);
+   |     -------------- ^^^^^^ expected `str`, found struct `String`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected enum `Option<&str>`
+              found enum `Option<&String>`
+note: function defined here
+  --> $DIR/issue-89856.rs:1:4
+   |
+LL | fn take_str_maybe(x: Option<&str>) -> Option<&str> { None }
+   |    ^^^^^^^^^^^^^^ ---------------
+help: try converting the passed type into a `&str`
+   |
+LL |     take_str_maybe(option.map(|x| &**x));
+   |                          ++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-89935.rs b/src/test/ui/typeck/issue-89935.rs
new file mode 100644
index 000000000..03f8f09a7
--- /dev/null
+++ b/src/test/ui/typeck/issue-89935.rs
@@ -0,0 +1,18 @@
+// check-pass
+
+trait Foo: Baz {}
+trait Bar {}
+trait Baz: Bar {
+    fn bar(&self);
+}
+
+impl<T: Foo> Bar for T {}
+impl<T: Foo> Baz for T {
+    fn bar(&self) {}
+}
+
+fn accept_foo(x: Box<dyn Foo>) {
+    x.bar();
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-90101.rs b/src/test/ui/typeck/issue-90101.rs
new file mode 100644
index 000000000..1954ee6f1
--- /dev/null
+++ b/src/test/ui/typeck/issue-90101.rs
@@ -0,0 +1,8 @@
+use std::path::{Path, PathBuf};
+
+fn func(path: impl Into<PathBuf>, code: impl Into<String>) {}
+
+fn main() {
+    func(Path::new("hello").to_path_buf().to_string_lossy(), "world")
+    //~^ ERROR [E0277]
+}
diff --git a/src/test/ui/typeck/issue-90101.stderr b/src/test/ui/typeck/issue-90101.stderr
new file mode 100644
index 000000000..ab9a72edf
--- /dev/null
+++ b/src/test/ui/typeck/issue-90101.stderr
@@ -0,0 +1,24 @@
+error[E0277]: the trait bound `PathBuf: From<Cow<'_, str>>` is not satisfied
+  --> $DIR/issue-90101.rs:6:10
+   |
+LL |     func(Path::new("hello").to_path_buf().to_string_lossy(), "world")
+   |     ---- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<Cow<'_, str>>` is not implemented for `PathBuf`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: the following other types implement trait `From<T>`:
+             <PathBuf as From<&T>>
+             <PathBuf as From<Box<Path>>>
+             <PathBuf as From<Cow<'a, Path>>>
+             <PathBuf as From<OsString>>
+             <PathBuf as From<String>>
+   = note: required because of the requirements on the impl of `Into<PathBuf>` for `Cow<'_, str>`
+note: required by a bound in `func`
+  --> $DIR/issue-90101.rs:3:20
+   |
+LL | fn func(path: impl Into<PathBuf>, code: impl Into<String>) {}
+   |                    ^^^^^^^^^^^^^ required by this bound in `func`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/typeck/issue-90164.rs b/src/test/ui/typeck/issue-90164.rs
new file mode 100644
index 000000000..63350433e
--- /dev/null
+++ b/src/test/ui/typeck/issue-90164.rs
@@ -0,0 +1,9 @@
+fn copy<R: Unpin, W>(_: R, _: W) {}
+
+fn f<T>(r: T) {
+    let w = ();
+    copy(r, w);
+    //~^ ERROR [E0277]
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-90164.stderr b/src/test/ui/typeck/issue-90164.stderr
new file mode 100644
index 000000000..1e2f1bae3
--- /dev/null
+++ b/src/test/ui/typeck/issue-90164.stderr
@@ -0,0 +1,22 @@
+error[E0277]: `T` cannot be unpinned
+  --> $DIR/issue-90164.rs:5:10
+   |
+LL |     copy(r, w);
+   |     ---- ^ the trait `Unpin` is not implemented for `T`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = note: consider using `Box::pin`
+note: required by a bound in `copy`
+  --> $DIR/issue-90164.rs:1:12
+   |
+LL | fn copy<R: Unpin, W>(_: R, _: W) {}
+   |            ^^^^^ required by this bound in `copy`
+help: consider restricting type parameter `T`
+   |
+LL | fn f<T: std::marker::Unpin>(r: T) {
+   |       ++++++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/typeck/issue-90319.rs b/src/test/ui/typeck/issue-90319.rs
new file mode 100644
index 000000000..57e6ac7cf
--- /dev/null
+++ b/src/test/ui/typeck/issue-90319.rs
@@ -0,0 +1,17 @@
+struct Wrapper<T>(T);
+
+trait Trait {
+    fn method(&self) {}
+}
+
+impl<'a, T> Trait for Wrapper<&'a T> where Wrapper<T>: Trait {}
+
+fn get<T>() -> T {
+    unimplemented!()
+}
+
+fn main() {
+    let thing = get::<Thing>();//~ERROR cannot find type `Thing` in this scope [E0412]
+    let wrapper = Wrapper(thing);
+    Trait::method(&wrapper);
+}
diff --git a/src/test/ui/typeck/issue-90319.stderr b/src/test/ui/typeck/issue-90319.stderr
new file mode 100644
index 000000000..61549dd70
--- /dev/null
+++ b/src/test/ui/typeck/issue-90319.stderr
@@ -0,0 +1,9 @@
+error[E0412]: cannot find type `Thing` in this scope
+  --> $DIR/issue-90319.rs:14:23
+   |
+LL |     let thing = get::<Thing>();
+   |                       ^^^^^ not found in this scope
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0412`.
diff --git a/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.rs b/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.rs
new file mode 100644
index 000000000..74e50d46e
--- /dev/null
+++ b/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.rs
@@ -0,0 +1,14 @@
+// edition:2021
+
+mod m {
+  pub struct S { foo: i32 }
+  impl S {
+    pub fn foo(&self) -> i32 { 42 }
+  }
+}
+
+fn bar(s: &m::S) {
+  || s.foo() + s.foo; //~ ERROR E0616
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.stderr b/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.stderr
new file mode 100644
index 000000000..02cdc102c
--- /dev/null
+++ b/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.stderr
@@ -0,0 +1,14 @@
+error[E0616]: field `foo` of struct `S` is private
+  --> $DIR/issue-90483-inaccessible-field-adjustment.rs:11:18
+   |
+LL |   || s.foo() + s.foo;
+   |                  ^^^ private field
+   |
+help: a method `foo` also exists, call it with parentheses
+   |
+LL |   || s.foo() + s.foo();
+   |                     ++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0616`.
diff --git a/src/test/ui/typeck/issue-90804-incorrect-reference-suggestion.rs b/src/test/ui/typeck/issue-90804-incorrect-reference-suggestion.rs
new file mode 100644
index 000000000..f891a42fc
--- /dev/null
+++ b/src/test/ui/typeck/issue-90804-incorrect-reference-suggestion.rs
@@ -0,0 +1,11 @@
+// Do not suggest referencing the parameter to `check`
+
+trait Marker<T> {}
+
+impl<T> Marker<i32> for T {}
+
+pub fn check<T: Marker<u32>>(_: T) {}
+
+pub fn main() {
+    check::<()>(()); //~ ERROR [E0277]
+}
diff --git a/src/test/ui/typeck/issue-90804-incorrect-reference-suggestion.stderr b/src/test/ui/typeck/issue-90804-incorrect-reference-suggestion.stderr
new file mode 100644
index 000000000..08eab0253
--- /dev/null
+++ b/src/test/ui/typeck/issue-90804-incorrect-reference-suggestion.stderr
@@ -0,0 +1,17 @@
+error[E0277]: the trait bound `(): Marker<u32>` is not satisfied
+  --> $DIR/issue-90804-incorrect-reference-suggestion.rs:10:17
+   |
+LL |     check::<()>(());
+   |     ----------- ^^ the trait `Marker<u32>` is not implemented for `()`
+   |     |
+   |     required by a bound introduced by this call
+   |
+note: required by a bound in `check`
+  --> $DIR/issue-90804-incorrect-reference-suggestion.rs:7:17
+   |
+LL | pub fn check<T: Marker<u32>>(_: T) {}
+   |                 ^^^^^^^^^^^ required by this bound in `check`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/typeck/issue-91210-ptr-method.fixed b/src/test/ui/typeck/issue-91210-ptr-method.fixed
new file mode 100644
index 000000000..94200cce7
--- /dev/null
+++ b/src/test/ui/typeck/issue-91210-ptr-method.fixed
@@ -0,0 +1,15 @@
+// Regression test for issue #91210.
+
+// run-rustfix
+
+#![allow(unused)]
+
+struct Foo { read: i32 }
+
+unsafe fn blah(x: *mut Foo) {
+    (*x).read = 4;
+    //~^ ERROR: attempted to take value of method
+    //~| HELP: to access the field, dereference first
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-91210-ptr-method.rs b/src/test/ui/typeck/issue-91210-ptr-method.rs
new file mode 100644
index 000000000..ed0ce6eff
--- /dev/null
+++ b/src/test/ui/typeck/issue-91210-ptr-method.rs
@@ -0,0 +1,15 @@
+// Regression test for issue #91210.
+
+// run-rustfix
+
+#![allow(unused)]
+
+struct Foo { read: i32 }
+
+unsafe fn blah(x: *mut Foo) {
+    x.read = 4;
+    //~^ ERROR: attempted to take value of method
+    //~| HELP: to access the field, dereference first
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-91210-ptr-method.stderr b/src/test/ui/typeck/issue-91210-ptr-method.stderr
new file mode 100644
index 000000000..503a32373
--- /dev/null
+++ b/src/test/ui/typeck/issue-91210-ptr-method.stderr
@@ -0,0 +1,11 @@
+error[E0615]: attempted to take value of method `read` on type `*mut Foo`
+  --> $DIR/issue-91210-ptr-method.rs:10:7
+   |
+LL |     x.read = 4;
+   |     - ^^^^ method, not a field
+   |     |
+   |     help: to access the field, dereference first: `(*x)`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0615`.
diff --git a/src/test/ui/typeck/issue-91267.rs b/src/test/ui/typeck/issue-91267.rs
new file mode 100644
index 000000000..f5a37e9cb
--- /dev/null
+++ b/src/test/ui/typeck/issue-91267.rs
@@ -0,0 +1,6 @@
+fn main() {
+    0: u8<e<5>=e>
+    //~^ ERROR: cannot find type `e` in this scope [E0412]
+    //~| ERROR: associated type bindings are not allowed here [E0229]
+    //~| ERROR: mismatched types [E0308]
+}
diff --git a/src/test/ui/typeck/issue-91267.stderr b/src/test/ui/typeck/issue-91267.stderr
new file mode 100644
index 000000000..aac00b9b6
--- /dev/null
+++ b/src/test/ui/typeck/issue-91267.stderr
@@ -0,0 +1,27 @@
+error[E0412]: cannot find type `e` in this scope
+  --> $DIR/issue-91267.rs:2:16
+   |
+LL |     0: u8<e<5>=e>
+   |                ^
+   |                |
+   |                not found in this scope
+   |                help: maybe you meant to write an assignment here: `let e`
+
+error[E0229]: associated type bindings are not allowed here
+  --> $DIR/issue-91267.rs:2:11
+   |
+LL |     0: u8<e<5>=e>
+   |           ^^^^^^ associated type not allowed here
+
+error[E0308]: mismatched types
+  --> $DIR/issue-91267.rs:2:5
+   |
+LL | fn main() {
+   |           - expected `()` because of default return type
+LL |     0: u8<e<5>=e>
+   |     ^^^^^^^^^^^^^ expected `()`, found `u8`
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0229, E0308, E0412.
+For more information about an error, try `rustc --explain E0229`.
diff --git a/src/test/ui/typeck/issue-91328.fixed b/src/test/ui/typeck/issue-91328.fixed
new file mode 100644
index 000000000..c0384399a
--- /dev/null
+++ b/src/test/ui/typeck/issue-91328.fixed
@@ -0,0 +1,47 @@
+// Regression test for issue #91328.
+
+// run-rustfix
+
+#![allow(dead_code)]
+
+fn foo(r: Result<Vec<i32>, i32>) -> i32 {
+    match r.as_deref() {
+    //~^ HELP: consider using `as_deref` here
+        Ok([a, b]) => a + b,
+        //~^ ERROR: expected an array or slice
+        //~| NOTE: pattern cannot match with input type
+        _ => 42,
+    }
+}
+
+fn bar(o: Option<Vec<i32>>) -> i32 {
+    match o.as_deref() {
+    //~^ HELP: consider using `as_deref` here
+        Some([a, b]) => a + b,
+        //~^ ERROR: expected an array or slice
+        //~| NOTE: pattern cannot match with input type
+        _ => 42,
+    }
+}
+
+fn baz(v: Vec<i32>) -> i32 {
+    match v[..] {
+    //~^ HELP: consider slicing here
+        [a, b] => a + b,
+        //~^ ERROR: expected an array or slice
+        //~| NOTE: pattern cannot match with input type
+        _ => 42,
+    }
+}
+
+fn qux(a: &Option<Box<[i32; 2]>>) -> i32 {
+    match a.as_deref() {
+    //~^ HELP: consider using `as_deref` here
+        Some([a, b]) => a + b,
+        //~^ ERROR: expected an array or slice
+        //~| NOTE: pattern cannot match with input type
+        _ => 42,
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-91328.rs b/src/test/ui/typeck/issue-91328.rs
new file mode 100644
index 000000000..63602d26f
--- /dev/null
+++ b/src/test/ui/typeck/issue-91328.rs
@@ -0,0 +1,47 @@
+// Regression test for issue #91328.
+
+// run-rustfix
+
+#![allow(dead_code)]
+
+fn foo(r: Result<Vec<i32>, i32>) -> i32 {
+    match r {
+    //~^ HELP: consider using `as_deref` here
+        Ok([a, b]) => a + b,
+        //~^ ERROR: expected an array or slice
+        //~| NOTE: pattern cannot match with input type
+        _ => 42,
+    }
+}
+
+fn bar(o: Option<Vec<i32>>) -> i32 {
+    match o {
+    //~^ HELP: consider using `as_deref` here
+        Some([a, b]) => a + b,
+        //~^ ERROR: expected an array or slice
+        //~| NOTE: pattern cannot match with input type
+        _ => 42,
+    }
+}
+
+fn baz(v: Vec<i32>) -> i32 {
+    match v {
+    //~^ HELP: consider slicing here
+        [a, b] => a + b,
+        //~^ ERROR: expected an array or slice
+        //~| NOTE: pattern cannot match with input type
+        _ => 42,
+    }
+}
+
+fn qux(a: &Option<Box<[i32; 2]>>) -> i32 {
+    match a {
+    //~^ HELP: consider using `as_deref` here
+        Some([a, b]) => a + b,
+        //~^ ERROR: expected an array or slice
+        //~| NOTE: pattern cannot match with input type
+        _ => 42,
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-91328.stderr b/src/test/ui/typeck/issue-91328.stderr
new file mode 100644
index 000000000..f2f407bca
--- /dev/null
+++ b/src/test/ui/typeck/issue-91328.stderr
@@ -0,0 +1,39 @@
+error[E0529]: expected an array or slice, found `Vec<i32>`
+  --> $DIR/issue-91328.rs:10:12
+   |
+LL |     match r {
+   |           - help: consider using `as_deref` here: `r.as_deref()`
+LL |
+LL |         Ok([a, b]) => a + b,
+   |            ^^^^^^ pattern cannot match with input type `Vec<i32>`
+
+error[E0529]: expected an array or slice, found `Vec<i32>`
+  --> $DIR/issue-91328.rs:20:14
+   |
+LL |     match o {
+   |           - help: consider using `as_deref` here: `o.as_deref()`
+LL |
+LL |         Some([a, b]) => a + b,
+   |              ^^^^^^ pattern cannot match with input type `Vec<i32>`
+
+error[E0529]: expected an array or slice, found `Vec<i32>`
+  --> $DIR/issue-91328.rs:30:9
+   |
+LL |     match v {
+   |           - help: consider slicing here: `v[..]`
+LL |
+LL |         [a, b] => a + b,
+   |         ^^^^^^ pattern cannot match with input type `Vec<i32>`
+
+error[E0529]: expected an array or slice, found `Box<[i32; 2]>`
+  --> $DIR/issue-91328.rs:40:14
+   |
+LL |     match a {
+   |           - help: consider using `as_deref` here: `a.as_deref()`
+LL |
+LL |         Some([a, b]) => a + b,
+   |              ^^^^^^ pattern cannot match with input type `Box<[i32; 2]>`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0529`.
diff --git a/src/test/ui/typeck/issue-91334.rs b/src/test/ui/typeck/issue-91334.rs
new file mode 100644
index 000000000..bf9a5a626
--- /dev/null
+++ b/src/test/ui/typeck/issue-91334.rs
@@ -0,0 +1,10 @@
+// Regression test for the ICE described in issue #91334.
+
+// error-pattern: this file contains an unclosed delimiter
+// error-pattern: expected one of
+// error-pattern: mismatched closing delimiter
+// error-pattern: mismatched types
+
+#![feature(generators)]
+
+fn f(){||yield(((){),
diff --git a/src/test/ui/typeck/issue-91334.stderr b/src/test/ui/typeck/issue-91334.stderr
new file mode 100644
index 000000000..8508f7a38
--- /dev/null
+++ b/src/test/ui/typeck/issue-91334.stderr
@@ -0,0 +1,50 @@
+error: this file contains an unclosed delimiter
+  --> $DIR/issue-91334.rs:10:23
+   |
+LL | fn f(){||yield(((){),
+   |       -       -       ^
+   |       |       |
+   |       |       unclosed delimiter
+   |       unclosed delimiter
+
+error: this file contains an unclosed delimiter
+  --> $DIR/issue-91334.rs:10:23
+   |
+LL | fn f(){||yield(((){),
+   |       -       -       ^
+   |       |       |
+   |       |       unclosed delimiter
+   |       unclosed delimiter
+
+error: expected one of `)`, `,`, `.`, `?`, or an operator, found `{`
+  --> $DIR/issue-91334.rs:10:19
+   |
+LL | fn f(){||yield(((){),
+   |                   ^
+   |                   |
+   |                   expected one of `)`, `,`, `.`, `?`, or an operator
+   |                   help: missing `,`
+
+error: mismatched closing delimiter: `)`
+  --> $DIR/issue-91334.rs:10:19
+   |
+LL | fn f(){||yield(((){),
+   |                -  ^^ mismatched closing delimiter
+   |                |  |
+   |                |  unclosed delimiter
+   |                closing delimiter possibly meant for this
+
+error[E0308]: mismatched types
+  --> $DIR/issue-91334.rs:10:8
+   |
+LL | fn f(){||yield(((){),
+   |       -^^^^^^^^^^^^^^^ expected `()`, found generator
+   |       |
+   |       help: a return type might be missing here: `-> _`
+   |
+   = note: expected unit type `()`
+              found generator `[generator@$DIR/issue-91334.rs:10:8: 10:10]`
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/issue-91450-inner-ty-error.rs b/src/test/ui/typeck/issue-91450-inner-ty-error.rs
new file mode 100644
index 000000000..3c7c990d4
--- /dev/null
+++ b/src/test/ui/typeck/issue-91450-inner-ty-error.rs
@@ -0,0 +1,7 @@
+// Regression test for #91450.
+// This test ensures that the compiler does not suggest `Foo<[type error]>` in diagnostic messages.
+
+fn foo() -> Option<_> {} //~ ERROR: [E0308]
+//~^ ERROR: the placeholder `_` is not allowed
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-91450-inner-ty-error.stderr b/src/test/ui/typeck/issue-91450-inner-ty-error.stderr
new file mode 100644
index 000000000..32f4c8f6f
--- /dev/null
+++ b/src/test/ui/typeck/issue-91450-inner-ty-error.stderr
@@ -0,0 +1,21 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-91450-inner-ty-error.rs:4:13
+   |
+LL | fn foo() -> Option<_> {}
+   |    ---      ^^^^^^^^^ expected enum `Option`, found `()`
+   |    |
+   |    implicitly returns `()` as its body has no tail or `return` expression
+   |
+   = note:   expected enum `Option<_>`
+           found unit type `()`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/issue-91450-inner-ty-error.rs:4:20
+   |
+LL | fn foo() -> Option<_> {}
+   |                    ^ not allowed in type signatures
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0121, E0308.
+For more information about an error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/issue-93486.rs b/src/test/ui/typeck/issue-93486.rs
new file mode 100644
index 000000000..f8f98d5c1
--- /dev/null
+++ b/src/test/ui/typeck/issue-93486.rs
@@ -0,0 +1,6 @@
+fn main() {
+    while let 1 = 1 {
+        vec![].last_mut().unwrap() = 3_u8;
+        //~^ ERROR invalid left-hand side of assignment
+    }
+}
diff --git a/src/test/ui/typeck/issue-93486.stderr b/src/test/ui/typeck/issue-93486.stderr
new file mode 100644
index 000000000..167edc894
--- /dev/null
+++ b/src/test/ui/typeck/issue-93486.stderr
@@ -0,0 +1,16 @@
+error[E0070]: invalid left-hand side of assignment
+  --> $DIR/issue-93486.rs:3:36
+   |
+LL |         vec![].last_mut().unwrap() = 3_u8;
+   |         -------------------------- ^
+   |         |
+   |         cannot assign to this expression
+   |
+help: consider dereferencing here to assign to the mutably borrowed value
+   |
+LL |         *vec![].last_mut().unwrap() = 3_u8;
+   |         +
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0070`.
diff --git a/src/test/ui/typeck/issue-96738.rs b/src/test/ui/typeck/issue-96738.rs
new file mode 100644
index 000000000..ce2556f86
--- /dev/null
+++ b/src/test/ui/typeck/issue-96738.rs
@@ -0,0 +1,4 @@
+fn main() {
+    Some.nonexistent_method(); //~ ERROR: no method named `nonexistent_method` found
+    Some.nonexistent_field; //~ ERROR: no field `nonexistent_field`
+}
diff --git a/src/test/ui/typeck/issue-96738.stderr b/src/test/ui/typeck/issue-96738.stderr
new file mode 100644
index 000000000..32f538498
--- /dev/null
+++ b/src/test/ui/typeck/issue-96738.stderr
@@ -0,0 +1,30 @@
+error[E0599]: no method named `nonexistent_method` found for fn item `fn(_) -> Option<_> {Option::<_>::Some}` in the current scope
+  --> $DIR/issue-96738.rs:2:10
+   |
+LL |     Some.nonexistent_method();
+   |     ---- ^^^^^^^^^^^^^^^^^^ method not found in `fn(_) -> Option<_> {Option::<_>::Some}`
+   |     |
+   |     this is the constructor of an enum variant
+   |
+help: call the constructor
+   |
+LL |     (Some)(_).nonexistent_method();
+   |     +    ++++
+
+error[E0609]: no field `nonexistent_field` on type `fn(_) -> Option<_> {Option::<_>::Some}`
+  --> $DIR/issue-96738.rs:3:10
+   |
+LL |     Some.nonexistent_field;
+   |     ---- ^^^^^^^^^^^^^^^^^
+   |     |
+   |     this is the constructor of an enum variant
+   |
+help: call the constructor
+   |
+LL |     (Some)(_).nonexistent_field;
+   |     +    ++++
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0599, E0609.
+For more information about an error, try `rustc --explain E0599`.
diff --git a/src/test/ui/typeck/issue-98260.rs b/src/test/ui/typeck/issue-98260.rs
new file mode 100644
index 000000000..cf48294e1
--- /dev/null
+++ b/src/test/ui/typeck/issue-98260.rs
@@ -0,0 +1,9 @@
+fn main() {}
+trait A {
+    fn a(aa: B) -> Result<_, B> {
+    //~^ ERROR: the placeholder `_` is not allowed within types on item signatures for return types [E0121]
+        Ok(())
+    }
+}
+
+enum B {}
diff --git a/src/test/ui/typeck/issue-98260.stderr b/src/test/ui/typeck/issue-98260.stderr
new file mode 100644
index 000000000..08a1d17e2
--- /dev/null
+++ b/src/test/ui/typeck/issue-98260.stderr
@@ -0,0 +1,12 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/issue-98260.rs:3:27
+   |
+LL |     fn a(aa: B) -> Result<_, B> {
+   |                    -------^----
+   |                    |      |
+   |                    |      not allowed in type signatures
+   |                    help: replace with the correct return type: `Result<(), B>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/missing-private-fields-in-struct-literal.rs b/src/test/ui/typeck/missing-private-fields-in-struct-literal.rs
new file mode 100644
index 000000000..9f1560bfb
--- /dev/null
+++ b/src/test/ui/typeck/missing-private-fields-in-struct-literal.rs
@@ -0,0 +1,18 @@
+pub mod m {
+    pub struct S {
+        pub visible: bool,
+        a: (),
+        b: (),
+        c: (),
+        d: (),
+        e: (),
+    }
+}
+
+fn main() {
+    let _ = m::S { //~ ERROR cannot construct `S` with struct literal syntax due to private fields
+        visible: true,
+        a: (),
+        b: (),
+    };
+}
diff --git a/src/test/ui/typeck/missing-private-fields-in-struct-literal.stderr b/src/test/ui/typeck/missing-private-fields-in-struct-literal.stderr
new file mode 100644
index 000000000..234110f31
--- /dev/null
+++ b/src/test/ui/typeck/missing-private-fields-in-struct-literal.stderr
@@ -0,0 +1,15 @@
+error: cannot construct `S` with struct literal syntax due to private fields
+  --> $DIR/missing-private-fields-in-struct-literal.rs:13:13
+   |
+LL |     let _ = m::S {
+   |             ^^^^
+LL |         visible: true,
+LL |         a: (),
+   |         ----- private field
+LL |         b: (),
+   |         ----- private field
+   |
+   = note: ... and other private fields `c`, `d` and `e` that were not provided
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/typeck/no-type-for-node-ice.rs b/src/test/ui/typeck/no-type-for-node-ice.rs
new file mode 100644
index 000000000..d0cfdbf50
--- /dev/null
+++ b/src/test/ui/typeck/no-type-for-node-ice.rs
@@ -0,0 +1,5 @@
+// Related issues: #20401, #20506, #20614, #20752, #20829, #20846, #20885, #20886
+
+fn main() {
+    "".homura[""]; //~ no field `homura` on type `&'static str`
+}
diff --git a/src/test/ui/typeck/no-type-for-node-ice.stderr b/src/test/ui/typeck/no-type-for-node-ice.stderr
new file mode 100644
index 000000000..b50241fb1
--- /dev/null
+++ b/src/test/ui/typeck/no-type-for-node-ice.stderr
@@ -0,0 +1,9 @@
+error[E0609]: no field `homura` on type `&'static str`
+  --> $DIR/no-type-for-node-ice.rs:4:8
+   |
+LL |     "".homura[""];
+   |        ^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0609`.
diff --git a/src/test/ui/typeck/point-at-type-parameter-definition.rs b/src/test/ui/typeck/point-at-type-parameter-definition.rs
new file mode 100644
index 000000000..856c0db08
--- /dev/null
+++ b/src/test/ui/typeck/point-at-type-parameter-definition.rs
@@ -0,0 +1,17 @@
+trait Trait {
+    fn do_stuff(&self);
+}
+
+struct Hello;
+
+impl Hello {
+    fn method(&self) {}
+}
+
+impl<Hello> Trait for Vec<Hello> {
+    fn do_stuff(&self) {
+        self[0].method(); //~ ERROR no method named `method` found for type parameter `Hello` in the current scope
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/point-at-type-parameter-definition.stderr b/src/test/ui/typeck/point-at-type-parameter-definition.stderr
new file mode 100644
index 000000000..8a6ab6110
--- /dev/null
+++ b/src/test/ui/typeck/point-at-type-parameter-definition.stderr
@@ -0,0 +1,12 @@
+error[E0599]: no method named `method` found for type parameter `Hello` in the current scope
+  --> $DIR/point-at-type-parameter-definition.rs:13:17
+   |
+LL | impl<Hello> Trait for Vec<Hello> {
+   |      ----- method `method` not found for this type parameter
+LL |     fn do_stuff(&self) {
+LL |         self[0].method();
+   |                 ^^^^^^ method not found in `Hello`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.
diff --git a/src/test/ui/typeck/prim-with-args.fixed b/src/test/ui/typeck/prim-with-args.fixed
new file mode 100644
index 000000000..e3f99479a
--- /dev/null
+++ b/src/test/ui/typeck/prim-with-args.fixed
@@ -0,0 +1,28 @@
+// run-rustfix
+fn main() {
+
+let _x: isize; //~ ERROR type arguments are not allowed on builtin type
+let _x: i8; //~ ERROR type arguments are not allowed on builtin type
+let _x: i16; //~ ERROR type arguments are not allowed on builtin type
+let _x: i32; //~ ERROR type arguments are not allowed on builtin type
+let _x: i64; //~ ERROR type arguments are not allowed on builtin type
+let _x: usize; //~ ERROR type arguments are not allowed on builtin type
+let _x: u8; //~ ERROR type arguments are not allowed on builtin type
+let _x: u16; //~ ERROR type arguments are not allowed on builtin type
+let _x: u32; //~ ERROR type arguments are not allowed on builtin type
+let _x: u64; //~ ERROR type arguments are not allowed on builtin type
+let _x: char; //~ ERROR type arguments are not allowed on builtin type
+
+let _x: isize; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: i8; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: i16; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: i32; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: i64; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: usize; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: u8; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: u16; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: u32; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: u64; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: char; //~ ERROR lifetime arguments are not allowed on builtin type
+
+}
diff --git a/src/test/ui/typeck/prim-with-args.rs b/src/test/ui/typeck/prim-with-args.rs
new file mode 100644
index 000000000..b10471ecc
--- /dev/null
+++ b/src/test/ui/typeck/prim-with-args.rs
@@ -0,0 +1,28 @@
+// run-rustfix
+fn main() {
+
+let _x: isize<isize>; //~ ERROR type arguments are not allowed on builtin type
+let _x: i8<isize>; //~ ERROR type arguments are not allowed on builtin type
+let _x: i16<isize>; //~ ERROR type arguments are not allowed on builtin type
+let _x: i32<isize>; //~ ERROR type arguments are not allowed on builtin type
+let _x: i64<isize>; //~ ERROR type arguments are not allowed on builtin type
+let _x: usize<isize>; //~ ERROR type arguments are not allowed on builtin type
+let _x: u8<isize>; //~ ERROR type arguments are not allowed on builtin type
+let _x: u16<isize>; //~ ERROR type arguments are not allowed on builtin type
+let _x: u32<isize>; //~ ERROR type arguments are not allowed on builtin type
+let _x: u64<isize>; //~ ERROR type arguments are not allowed on builtin type
+let _x: char<isize>; //~ ERROR type arguments are not allowed on builtin type
+
+let _x: isize<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: i8<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: i16<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: i32<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: i64<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: usize<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: u8<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: u16<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: u32<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: u64<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+let _x: char<'static>; //~ ERROR lifetime arguments are not allowed on builtin type
+
+}
diff --git a/src/test/ui/typeck/prim-with-args.stderr b/src/test/ui/typeck/prim-with-args.stderr
new file mode 100644
index 000000000..2ddad5ad7
--- /dev/null
+++ b/src/test/ui/typeck/prim-with-args.stderr
@@ -0,0 +1,311 @@
+error[E0109]: type arguments are not allowed on builtin type `isize`
+  --> $DIR/prim-with-args.rs:4:15
+   |
+LL | let _x: isize<isize>;
+   |         ----- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `isize`
+   |
+help: primitive type `isize` doesn't have generic parameters
+   |
+LL - let _x: isize<isize>;
+LL + let _x: isize;
+   |
+
+error[E0109]: type arguments are not allowed on builtin type `i8`
+  --> $DIR/prim-with-args.rs:5:12
+   |
+LL | let _x: i8<isize>;
+   |         -- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `i8`
+   |
+help: primitive type `i8` doesn't have generic parameters
+   |
+LL - let _x: i8<isize>;
+LL + let _x: i8;
+   |
+
+error[E0109]: type arguments are not allowed on builtin type `i16`
+  --> $DIR/prim-with-args.rs:6:13
+   |
+LL | let _x: i16<isize>;
+   |         --- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `i16`
+   |
+help: primitive type `i16` doesn't have generic parameters
+   |
+LL - let _x: i16<isize>;
+LL + let _x: i16;
+   |
+
+error[E0109]: type arguments are not allowed on builtin type `i32`
+  --> $DIR/prim-with-args.rs:7:13
+   |
+LL | let _x: i32<isize>;
+   |         --- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `i32`
+   |
+help: primitive type `i32` doesn't have generic parameters
+   |
+LL - let _x: i32<isize>;
+LL + let _x: i32;
+   |
+
+error[E0109]: type arguments are not allowed on builtin type `i64`
+  --> $DIR/prim-with-args.rs:8:13
+   |
+LL | let _x: i64<isize>;
+   |         --- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `i64`
+   |
+help: primitive type `i64` doesn't have generic parameters
+   |
+LL - let _x: i64<isize>;
+LL + let _x: i64;
+   |
+
+error[E0109]: type arguments are not allowed on builtin type `usize`
+  --> $DIR/prim-with-args.rs:9:15
+   |
+LL | let _x: usize<isize>;
+   |         ----- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `usize`
+   |
+help: primitive type `usize` doesn't have generic parameters
+   |
+LL - let _x: usize<isize>;
+LL + let _x: usize;
+   |
+
+error[E0109]: type arguments are not allowed on builtin type `u8`
+  --> $DIR/prim-with-args.rs:10:12
+   |
+LL | let _x: u8<isize>;
+   |         -- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `u8`
+   |
+help: primitive type `u8` doesn't have generic parameters
+   |
+LL - let _x: u8<isize>;
+LL + let _x: u8;
+   |
+
+error[E0109]: type arguments are not allowed on builtin type `u16`
+  --> $DIR/prim-with-args.rs:11:13
+   |
+LL | let _x: u16<isize>;
+   |         --- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `u16`
+   |
+help: primitive type `u16` doesn't have generic parameters
+   |
+LL - let _x: u16<isize>;
+LL + let _x: u16;
+   |
+
+error[E0109]: type arguments are not allowed on builtin type `u32`
+  --> $DIR/prim-with-args.rs:12:13
+   |
+LL | let _x: u32<isize>;
+   |         --- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `u32`
+   |
+help: primitive type `u32` doesn't have generic parameters
+   |
+LL - let _x: u32<isize>;
+LL + let _x: u32;
+   |
+
+error[E0109]: type arguments are not allowed on builtin type `u64`
+  --> $DIR/prim-with-args.rs:13:13
+   |
+LL | let _x: u64<isize>;
+   |         --- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `u64`
+   |
+help: primitive type `u64` doesn't have generic parameters
+   |
+LL - let _x: u64<isize>;
+LL + let _x: u64;
+   |
+
+error[E0109]: type arguments are not allowed on builtin type `char`
+  --> $DIR/prim-with-args.rs:14:14
+   |
+LL | let _x: char<isize>;
+   |         ---- ^^^^^ type argument not allowed
+   |         |
+   |         not allowed on builtin type `char`
+   |
+help: primitive type `char` doesn't have generic parameters
+   |
+LL - let _x: char<isize>;
+LL + let _x: char;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `isize`
+  --> $DIR/prim-with-args.rs:16:15
+   |
+LL | let _x: isize<'static>;
+   |         ----- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `isize`
+   |
+help: primitive type `isize` doesn't have generic parameters
+   |
+LL - let _x: isize<'static>;
+LL + let _x: isize;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `i8`
+  --> $DIR/prim-with-args.rs:17:12
+   |
+LL | let _x: i8<'static>;
+   |         -- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `i8`
+   |
+help: primitive type `i8` doesn't have generic parameters
+   |
+LL - let _x: i8<'static>;
+LL + let _x: i8;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `i16`
+  --> $DIR/prim-with-args.rs:18:13
+   |
+LL | let _x: i16<'static>;
+   |         --- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `i16`
+   |
+help: primitive type `i16` doesn't have generic parameters
+   |
+LL - let _x: i16<'static>;
+LL + let _x: i16;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `i32`
+  --> $DIR/prim-with-args.rs:19:13
+   |
+LL | let _x: i32<'static>;
+   |         --- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `i32`
+   |
+help: primitive type `i32` doesn't have generic parameters
+   |
+LL - let _x: i32<'static>;
+LL + let _x: i32;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `i64`
+  --> $DIR/prim-with-args.rs:20:13
+   |
+LL | let _x: i64<'static>;
+   |         --- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `i64`
+   |
+help: primitive type `i64` doesn't have generic parameters
+   |
+LL - let _x: i64<'static>;
+LL + let _x: i64;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `usize`
+  --> $DIR/prim-with-args.rs:21:15
+   |
+LL | let _x: usize<'static>;
+   |         ----- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `usize`
+   |
+help: primitive type `usize` doesn't have generic parameters
+   |
+LL - let _x: usize<'static>;
+LL + let _x: usize;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `u8`
+  --> $DIR/prim-with-args.rs:22:12
+   |
+LL | let _x: u8<'static>;
+   |         -- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `u8`
+   |
+help: primitive type `u8` doesn't have generic parameters
+   |
+LL - let _x: u8<'static>;
+LL + let _x: u8;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `u16`
+  --> $DIR/prim-with-args.rs:23:13
+   |
+LL | let _x: u16<'static>;
+   |         --- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `u16`
+   |
+help: primitive type `u16` doesn't have generic parameters
+   |
+LL - let _x: u16<'static>;
+LL + let _x: u16;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `u32`
+  --> $DIR/prim-with-args.rs:24:13
+   |
+LL | let _x: u32<'static>;
+   |         --- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `u32`
+   |
+help: primitive type `u32` doesn't have generic parameters
+   |
+LL - let _x: u32<'static>;
+LL + let _x: u32;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `u64`
+  --> $DIR/prim-with-args.rs:25:13
+   |
+LL | let _x: u64<'static>;
+   |         --- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `u64`
+   |
+help: primitive type `u64` doesn't have generic parameters
+   |
+LL - let _x: u64<'static>;
+LL + let _x: u64;
+   |
+
+error[E0109]: lifetime arguments are not allowed on builtin type `char`
+  --> $DIR/prim-with-args.rs:26:14
+   |
+LL | let _x: char<'static>;
+   |         ---- ^^^^^^^ lifetime argument not allowed
+   |         |
+   |         not allowed on builtin type `char`
+   |
+help: primitive type `char` doesn't have generic parameters
+   |
+LL - let _x: char<'static>;
+LL + let _x: char;
+   |
+
+error: aborting due to 22 previous errors
+
+For more information about this error, try `rustc --explain E0109`.
diff --git a/src/test/ui/typeck/project-cache-issue-37154.rs b/src/test/ui/typeck/project-cache-issue-37154.rs
new file mode 100644
index 000000000..b10239c22
--- /dev/null
+++ b/src/test/ui/typeck/project-cache-issue-37154.rs
@@ -0,0 +1,21 @@
+// run-pass
+
+#![allow(dead_code)]
+// Regression test for #37154: the problem here was that the cache
+// results in a false error because it was caching placeholder results
+// even after those placeholder regions had been popped.
+
+trait Foo {
+    fn method(&self) {}
+}
+
+struct Wrapper<T>(T);
+
+impl<T> Foo for Wrapper<T> where for<'a> &'a T: IntoIterator<Item=&'a ()> {}
+
+fn f(x: Wrapper<Vec<()>>) {
+    x.method(); // This works.
+    x.method(); // error: no method named `method`
+}
+
+fn main() { }
diff --git a/src/test/ui/typeck/remove-extra-argument.fixed b/src/test/ui/typeck/remove-extra-argument.fixed
new file mode 100644
index 000000000..a9338c76c
--- /dev/null
+++ b/src/test/ui/typeck/remove-extra-argument.fixed
@@ -0,0 +1,9 @@
+// run-rustfix
+// Check that the HELP suggestion is `l(vec![])` instead of `l($crate::vec::Vec::new())`
+fn l(_a: Vec<u8>) {}
+
+fn main() {
+    l(vec![])
+    //~^ ERROR this function takes 1 argument but 2 arguments were supplied
+    //~| HELP remove the extra argument
+}
diff --git a/src/test/ui/typeck/remove-extra-argument.rs b/src/test/ui/typeck/remove-extra-argument.rs
new file mode 100644
index 000000000..659cb8b26
--- /dev/null
+++ b/src/test/ui/typeck/remove-extra-argument.rs
@@ -0,0 +1,9 @@
+// run-rustfix
+// Check that the HELP suggestion is `l(vec![])` instead of `l($crate::vec::Vec::new())`
+fn l(_a: Vec<u8>) {}
+
+fn main() {
+    l(vec![], vec![])
+    //~^ ERROR this function takes 1 argument but 2 arguments were supplied
+    //~| HELP remove the extra argument
+}
diff --git a/src/test/ui/typeck/remove-extra-argument.stderr b/src/test/ui/typeck/remove-extra-argument.stderr
new file mode 100644
index 000000000..703032a83
--- /dev/null
+++ b/src/test/ui/typeck/remove-extra-argument.stderr
@@ -0,0 +1,19 @@
+error[E0061]: this function takes 1 argument but 2 arguments were supplied
+  --> $DIR/remove-extra-argument.rs:6:5
+   |
+LL |     l(vec![], vec![])
+   |     ^         ------ argument of type `Vec<_>` unexpected
+   |
+note: function defined here
+  --> $DIR/remove-extra-argument.rs:3:4
+   |
+LL | fn l(_a: Vec<u8>) {}
+   |    ^ -----------
+help: remove the extra argument
+   |
+LL |     l(vec![])
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0061`.
diff --git a/src/test/ui/typeck/return_type_containing_closure.rs b/src/test/ui/typeck/return_type_containing_closure.rs
new file mode 100644
index 000000000..29624e08a
--- /dev/null
+++ b/src/test/ui/typeck/return_type_containing_closure.rs
@@ -0,0 +1,10 @@
+#[allow(unused)]
+fn foo() { //~ HELP a return type might be missing here
+    vec!['a'].iter().map(|c| c)
+    //~^ ERROR mismatched types [E0308]
+    //~| NOTE expected `()`, found struct `Map`
+    //~| NOTE expected unit type `()`
+    //~| HELP consider using a semicolon here
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/return_type_containing_closure.stderr b/src/test/ui/typeck/return_type_containing_closure.stderr
new file mode 100644
index 000000000..101aee395
--- /dev/null
+++ b/src/test/ui/typeck/return_type_containing_closure.stderr
@@ -0,0 +1,20 @@
+error[E0308]: mismatched types
+  --> $DIR/return_type_containing_closure.rs:3:5
+   |
+LL |     vec!['a'].iter().map(|c| c)
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found struct `Map`
+   |
+   = note: expected unit type `()`
+                 found struct `Map<std::slice::Iter<'_, char>, [closure@$DIR/return_type_containing_closure.rs:3:26: 3:29]>`
+help: consider using a semicolon here
+   |
+LL |     vec!['a'].iter().map(|c| c);
+   |                                +
+help: a return type might be missing here
+   |
+LL | fn foo() -> _ {
+   |          ++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/struct-enum-wrong-args.rs b/src/test/ui/typeck/struct-enum-wrong-args.rs
new file mode 100644
index 000000000..19de4d677
--- /dev/null
+++ b/src/test/ui/typeck/struct-enum-wrong-args.rs
@@ -0,0 +1,14 @@
+// Regression test of #86481.
+struct Wrapper(i32);
+struct DoubleWrapper(i32, i32);
+
+fn main() {
+    let _ = Some(3, 2); //~ ERROR this enum variant takes
+    let _ = Ok(3, 6, 2); //~ ERROR this enum variant takes
+    let _ = Ok(); //~ ERROR this enum variant takes
+    let _ = Wrapper(); //~ ERROR this struct takes
+    let _ = Wrapper(5, 2); //~ ERROR this struct takes
+    let _ = DoubleWrapper(); //~ ERROR this struct takes
+    let _ = DoubleWrapper(5); //~ ERROR this struct takes
+    let _ = DoubleWrapper(5, 2, 7); //~ ERROR this struct takes
+}
diff --git a/src/test/ui/typeck/struct-enum-wrong-args.stderr b/src/test/ui/typeck/struct-enum-wrong-args.stderr
new file mode 100644
index 000000000..f72082d53
--- /dev/null
+++ b/src/test/ui/typeck/struct-enum-wrong-args.stderr
@@ -0,0 +1,133 @@
+error[E0061]: this enum variant takes 1 argument but 2 arguments were supplied
+  --> $DIR/struct-enum-wrong-args.rs:6:13
+   |
+LL |     let _ = Some(3, 2);
+   |             ^^^^    - argument of type `{integer}` unexpected
+   |
+note: tuple variant defined here
+  --> $SRC_DIR/core/src/option.rs:LL:COL
+   |
+LL |     Some(#[stable(feature = "rust1", since = "1.0.0")] T),
+   |     ^^^^
+help: remove the extra argument
+   |
+LL |     let _ = Some(3);
+   |             ~~~~~~~
+
+error[E0061]: this enum variant takes 1 argument but 3 arguments were supplied
+  --> $DIR/struct-enum-wrong-args.rs:7:13
+   |
+LL |     let _ = Ok(3, 6, 2);
+   |             ^^    -  - argument of type `{integer}` unexpected
+   |                   |
+   |                   argument of type `{integer}` unexpected
+   |
+note: tuple variant defined here
+  --> $SRC_DIR/core/src/result.rs:LL:COL
+   |
+LL |     Ok(#[stable(feature = "rust1", since = "1.0.0")] T),
+   |     ^^
+help: remove the extra arguments
+   |
+LL |     let _ = Ok(3);
+   |             ~~~~~
+
+error[E0061]: this enum variant takes 1 argument but 0 arguments were supplied
+  --> $DIR/struct-enum-wrong-args.rs:8:13
+   |
+LL |     let _ = Ok();
+   |             ^^-- an argument is missing
+   |
+note: tuple variant defined here
+  --> $SRC_DIR/core/src/result.rs:LL:COL
+   |
+LL |     Ok(#[stable(feature = "rust1", since = "1.0.0")] T),
+   |     ^^
+help: provide the argument
+   |
+LL |     let _ = Ok(/* value */);
+   |             ~~~~~~~~~~~~~~~
+
+error[E0061]: this struct takes 1 argument but 0 arguments were supplied
+  --> $DIR/struct-enum-wrong-args.rs:9:13
+   |
+LL |     let _ = Wrapper();
+   |             ^^^^^^^-- an argument of type `i32` is missing
+   |
+note: tuple struct defined here
+  --> $DIR/struct-enum-wrong-args.rs:2:8
+   |
+LL | struct Wrapper(i32);
+   |        ^^^^^^^
+help: provide the argument
+   |
+LL |     let _ = Wrapper(/* i32 */);
+   |             ~~~~~~~~~~~~~~~~~~
+
+error[E0061]: this struct takes 1 argument but 2 arguments were supplied
+  --> $DIR/struct-enum-wrong-args.rs:10:13
+   |
+LL |     let _ = Wrapper(5, 2);
+   |             ^^^^^^^    - argument of type `{integer}` unexpected
+   |
+note: tuple struct defined here
+  --> $DIR/struct-enum-wrong-args.rs:2:8
+   |
+LL | struct Wrapper(i32);
+   |        ^^^^^^^
+help: remove the extra argument
+   |
+LL |     let _ = Wrapper(5);
+   |             ~~~~~~~~~~
+
+error[E0061]: this struct takes 2 arguments but 0 arguments were supplied
+  --> $DIR/struct-enum-wrong-args.rs:11:13
+   |
+LL |     let _ = DoubleWrapper();
+   |             ^^^^^^^^^^^^^-- two arguments of type `i32` and `i32` are missing
+   |
+note: tuple struct defined here
+  --> $DIR/struct-enum-wrong-args.rs:3:8
+   |
+LL | struct DoubleWrapper(i32, i32);
+   |        ^^^^^^^^^^^^^
+help: provide the arguments
+   |
+LL |     let _ = DoubleWrapper(/* i32 */, /* i32 */);
+   |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error[E0061]: this struct takes 2 arguments but 1 argument was supplied
+  --> $DIR/struct-enum-wrong-args.rs:12:13
+   |
+LL |     let _ = DoubleWrapper(5);
+   |             ^^^^^^^^^^^^^--- an argument of type `i32` is missing
+   |
+note: tuple struct defined here
+  --> $DIR/struct-enum-wrong-args.rs:3:8
+   |
+LL | struct DoubleWrapper(i32, i32);
+   |        ^^^^^^^^^^^^^
+help: provide the argument
+   |
+LL |     let _ = DoubleWrapper(5, /* i32 */);
+   |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error[E0061]: this struct takes 2 arguments but 3 arguments were supplied
+  --> $DIR/struct-enum-wrong-args.rs:13:13
+   |
+LL |     let _ = DoubleWrapper(5, 2, 7);
+   |             ^^^^^^^^^^^^^       - argument of type `{integer}` unexpected
+   |
+note: tuple struct defined here
+  --> $DIR/struct-enum-wrong-args.rs:3:8
+   |
+LL | struct DoubleWrapper(i32, i32);
+   |        ^^^^^^^^^^^^^
+help: remove the extra argument
+   |
+LL |     let _ = DoubleWrapper(5, 2);
+   |             ~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to 8 previous errors
+
+For more information about this error, try `rustc --explain E0061`.
diff --git a/src/test/ui/typeck/suggest-adding-missing-zero-to-floating-point-number.fixed b/src/test/ui/typeck/suggest-adding-missing-zero-to-floating-point-number.fixed
new file mode 100644
index 000000000..ba83e7900
--- /dev/null
+++ b/src/test/ui/typeck/suggest-adding-missing-zero-to-floating-point-number.fixed
@@ -0,0 +1,11 @@
+// run-rustfix
+
+fn main() {
+    2.0e1; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.0E1; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.0f32; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.0f64; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.0e+12; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.0e-12; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.0e1f32; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+}
diff --git a/src/test/ui/typeck/suggest-adding-missing-zero-to-floating-point-number.rs b/src/test/ui/typeck/suggest-adding-missing-zero-to-floating-point-number.rs
new file mode 100644
index 000000000..c102447f6
--- /dev/null
+++ b/src/test/ui/typeck/suggest-adding-missing-zero-to-floating-point-number.rs
@@ -0,0 +1,11 @@
+// run-rustfix
+
+fn main() {
+    2.e1; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.E1; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.f32; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.f64; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.e+12; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.e-12; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+    2.e1f32; //~ERROR `{integer}` is a primitive type and therefore doesn't have fields
+}
diff --git a/src/test/ui/typeck/suggest-adding-missing-zero-to-floating-point-number.stderr b/src/test/ui/typeck/suggest-adding-missing-zero-to-floating-point-number.stderr
new file mode 100644
index 000000000..e8e069708
--- /dev/null
+++ b/src/test/ui/typeck/suggest-adding-missing-zero-to-floating-point-number.stderr
@@ -0,0 +1,80 @@
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/suggest-adding-missing-zero-to-floating-point-number.rs:4:7
+   |
+LL |     2.e1;
+   |       ^^
+   |
+help: If the number is meant to be a floating point number, consider adding a `0` after the period
+   |
+LL |     2.0e1;
+   |       +
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/suggest-adding-missing-zero-to-floating-point-number.rs:5:7
+   |
+LL |     2.E1;
+   |       ^^
+   |
+help: If the number is meant to be a floating point number, consider adding a `0` after the period
+   |
+LL |     2.0E1;
+   |       +
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/suggest-adding-missing-zero-to-floating-point-number.rs:6:7
+   |
+LL |     2.f32;
+   |       ^^^
+   |
+help: If the number is meant to be a floating point number, consider adding a `0` after the period
+   |
+LL |     2.0f32;
+   |       +
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/suggest-adding-missing-zero-to-floating-point-number.rs:7:7
+   |
+LL |     2.f64;
+   |       ^^^
+   |
+help: If the number is meant to be a floating point number, consider adding a `0` after the period
+   |
+LL |     2.0f64;
+   |       +
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/suggest-adding-missing-zero-to-floating-point-number.rs:8:7
+   |
+LL |     2.e+12;
+   |       ^
+   |
+help: If the number is meant to be a floating point number, consider adding a `0` after the period
+   |
+LL |     2.0e+12;
+   |       +
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/suggest-adding-missing-zero-to-floating-point-number.rs:9:7
+   |
+LL |     2.e-12;
+   |       ^
+   |
+help: If the number is meant to be a floating point number, consider adding a `0` after the period
+   |
+LL |     2.0e-12;
+   |       +
+
+error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
+  --> $DIR/suggest-adding-missing-zero-to-floating-point-number.rs:10:7
+   |
+LL |     2.e1f32;
+   |       ^^^^^
+   |
+help: If the number is meant to be a floating point number, consider adding a `0` after the period
+   |
+LL |     2.0e1f32;
+   |       +
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0610`.
diff --git a/src/test/ui/typeck/type-placeholder-fn-in-const.rs b/src/test/ui/typeck/type-placeholder-fn-in-const.rs
new file mode 100644
index 000000000..ab2e2d8c5
--- /dev/null
+++ b/src/test/ui/typeck/type-placeholder-fn-in-const.rs
@@ -0,0 +1,14 @@
+struct MyStruct;
+
+trait Test {
+    const TEST: fn() -> _;
+    //~^ ERROR: the placeholder `_` is not allowed within types on item signatures for functions [E0121]
+    //~| ERROR: the placeholder `_` is not allowed within types on item signatures for constants [E0121]
+}
+
+impl Test for MyStruct {
+    const TEST: fn() -> _ = 42;
+    //~^ ERROR: the placeholder `_` is not allowed within types on item signatures for functions [E0121]
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/type-placeholder-fn-in-const.stderr b/src/test/ui/typeck/type-placeholder-fn-in-const.stderr
new file mode 100644
index 000000000..e7b2e554a
--- /dev/null
+++ b/src/test/ui/typeck/type-placeholder-fn-in-const.stderr
@@ -0,0 +1,21 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/type-placeholder-fn-in-const.rs:4:25
+   |
+LL |     const TEST: fn() -> _;
+   |                         ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/type-placeholder-fn-in-const.rs:4:25
+   |
+LL |     const TEST: fn() -> _;
+   |                         ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/type-placeholder-fn-in-const.rs:10:25
+   |
+LL |     const TEST: fn() -> _ = 42;
+   |                         ^ not allowed in type signatures
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/typeck-builtin-bound-type-parameters.rs b/src/test/ui/typeck/typeck-builtin-bound-type-parameters.rs
new file mode 100644
index 000000000..c463a8ad0
--- /dev/null
+++ b/src/test/ui/typeck/typeck-builtin-bound-type-parameters.rs
@@ -0,0 +1,17 @@
+fn foo1<T:Copy<U>, U>(x: T) {}
+//~^ ERROR this trait takes 0 generic arguments but 1 generic argument was supplied
+
+trait Trait: Copy<dyn Send> {}
+//~^ ERROR this trait takes 0 generic arguments but 1 generic argument was supplied
+
+struct MyStruct1<T: Copy<T>>;
+//~^ ERROR this trait takes 0 generic arguments but 1 generic argument was supplied
+
+struct MyStruct2<'a, T: Copy<'a>>;
+//~^ ERROR this trait takes 0 lifetime arguments but 1 lifetime argument was supplied
+
+fn foo2<'a, T:Copy<'a, U>, U>(x: T) {}
+//~^ ERROR this trait takes 0 lifetime arguments but 1 lifetime argument was supplied
+//~| ERROR this trait takes 0 generic arguments but 1 generic argument was supplied
+
+fn main() { }
diff --git a/src/test/ui/typeck/typeck-builtin-bound-type-parameters.stderr b/src/test/ui/typeck/typeck-builtin-bound-type-parameters.stderr
new file mode 100644
index 000000000..bf74dd7de
--- /dev/null
+++ b/src/test/ui/typeck/typeck-builtin-bound-type-parameters.stderr
@@ -0,0 +1,87 @@
+error[E0107]: this trait takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:1:11
+   |
+LL | fn foo1<T:Copy<U>, U>(x: T) {}
+   |           ^^^^--- help: remove these generics
+   |           |
+   |           expected 0 generic arguments
+   |
+note: trait defined here, with 0 generic parameters
+  --> $SRC_DIR/core/src/marker.rs:LL:COL
+   |
+LL | pub trait Copy: Clone {
+   |           ^^^^
+
+error[E0107]: this trait takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:4:14
+   |
+LL | trait Trait: Copy<dyn Send> {}
+   |              ^^^^---------- help: remove these generics
+   |              |
+   |              expected 0 generic arguments
+   |
+note: trait defined here, with 0 generic parameters
+  --> $SRC_DIR/core/src/marker.rs:LL:COL
+   |
+LL | pub trait Copy: Clone {
+   |           ^^^^
+
+error[E0107]: this trait takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:7:21
+   |
+LL | struct MyStruct1<T: Copy<T>>;
+   |                     ^^^^--- help: remove these generics
+   |                     |
+   |                     expected 0 generic arguments
+   |
+note: trait defined here, with 0 generic parameters
+  --> $SRC_DIR/core/src/marker.rs:LL:COL
+   |
+LL | pub trait Copy: Clone {
+   |           ^^^^
+
+error[E0107]: this trait takes 0 lifetime arguments but 1 lifetime argument was supplied
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:10:25
+   |
+LL | struct MyStruct2<'a, T: Copy<'a>>;
+   |                         ^^^^---- help: remove these generics
+   |                         |
+   |                         expected 0 lifetime arguments
+   |
+note: trait defined here, with 0 lifetime parameters
+  --> $SRC_DIR/core/src/marker.rs:LL:COL
+   |
+LL | pub trait Copy: Clone {
+   |           ^^^^
+
+error[E0107]: this trait takes 0 lifetime arguments but 1 lifetime argument was supplied
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:13:15
+   |
+LL | fn foo2<'a, T:Copy<'a, U>, U>(x: T) {}
+   |               ^^^^ -- help: remove this lifetime argument
+   |               |
+   |               expected 0 lifetime arguments
+   |
+note: trait defined here, with 0 lifetime parameters
+  --> $SRC_DIR/core/src/marker.rs:LL:COL
+   |
+LL | pub trait Copy: Clone {
+   |           ^^^^
+
+error[E0107]: this trait takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:13:15
+   |
+LL | fn foo2<'a, T:Copy<'a, U>, U>(x: T) {}
+   |               ^^^^     - help: remove this generic argument
+   |               |
+   |               expected 0 generic arguments
+   |
+note: trait defined here, with 0 generic parameters
+  --> $SRC_DIR/core/src/marker.rs:LL:COL
+   |
+LL | pub trait Copy: Clone {
+   |           ^^^^
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0107`.
diff --git a/src/test/ui/typeck/typeck-cast-pointer-to-float.rs b/src/test/ui/typeck/typeck-cast-pointer-to-float.rs
new file mode 100644
index 000000000..2af7a3cf2
--- /dev/null
+++ b/src/test/ui/typeck/typeck-cast-pointer-to-float.rs
@@ -0,0 +1,5 @@
+fn main() {
+    let x : i16 = 22;
+    ((&x) as *const i16) as f32;
+    //~^ ERROR casting `*const i16` as `f32` is invalid
+}
diff --git a/src/test/ui/typeck/typeck-cast-pointer-to-float.stderr b/src/test/ui/typeck/typeck-cast-pointer-to-float.stderr
new file mode 100644
index 000000000..81d968454
--- /dev/null
+++ b/src/test/ui/typeck/typeck-cast-pointer-to-float.stderr
@@ -0,0 +1,9 @@
+error[E0606]: casting `*const i16` as `f32` is invalid
+  --> $DIR/typeck-cast-pointer-to-float.rs:3:5
+   |
+LL |     ((&x) as *const i16) as f32;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0606`.
diff --git a/src/test/ui/typeck/typeck-closure-to-unsafe-fn-ptr.rs b/src/test/ui/typeck/typeck-closure-to-unsafe-fn-ptr.rs
new file mode 100644
index 000000000..2530a1e96
--- /dev/null
+++ b/src/test/ui/typeck/typeck-closure-to-unsafe-fn-ptr.rs
@@ -0,0 +1,9 @@
+// run-pass
+
+unsafe fn call_unsafe(func: unsafe fn() -> ()) -> () {
+    func()
+}
+
+pub fn main() {
+    unsafe { call_unsafe(|| {}); }
+}
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-assoc-type.fixed b/src/test/ui/typeck/typeck-default-trait-impl-assoc-type.fixed
new file mode 100644
index 000000000..a9107f998
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-assoc-type.fixed
@@ -0,0 +1,17 @@
+// run-rustfix
+// Test that we do not consider associated types to be sendable without
+// some applicable trait bound (and we don't ICE).
+#![allow(dead_code)]
+
+trait Trait {
+    type AssocType;
+    fn dummy(&self) { }
+}
+fn bar<T:Trait+Send>() where <T as Trait>::AssocType: Send {
+    is_send::<T::AssocType>(); //~ ERROR E0277
+}
+
+fn is_send<T:Send>() {
+}
+
+fn main() { }
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-assoc-type.rs b/src/test/ui/typeck/typeck-default-trait-impl-assoc-type.rs
new file mode 100644
index 000000000..bafc16577
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-assoc-type.rs
@@ -0,0 +1,17 @@
+// run-rustfix
+// Test that we do not consider associated types to be sendable without
+// some applicable trait bound (and we don't ICE).
+#![allow(dead_code)]
+
+trait Trait {
+    type AssocType;
+    fn dummy(&self) { }
+}
+fn bar<T:Trait+Send>() {
+    is_send::<T::AssocType>(); //~ ERROR E0277
+}
+
+fn is_send<T:Send>() {
+}
+
+fn main() { }
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-assoc-type.stderr b/src/test/ui/typeck/typeck-default-trait-impl-assoc-type.stderr
new file mode 100644
index 000000000..468a14762
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-assoc-type.stderr
@@ -0,0 +1,20 @@
+error[E0277]: `<T as Trait>::AssocType` cannot be sent between threads safely
+  --> $DIR/typeck-default-trait-impl-assoc-type.rs:11:15
+   |
+LL |     is_send::<T::AssocType>();
+   |               ^^^^^^^^^^^^ `<T as Trait>::AssocType` cannot be sent between threads safely
+   |
+   = help: the trait `Send` is not implemented for `<T as Trait>::AssocType`
+note: required by a bound in `is_send`
+  --> $DIR/typeck-default-trait-impl-assoc-type.rs:14:14
+   |
+LL | fn is_send<T:Send>() {
+   |              ^^^^ required by this bound in `is_send`
+help: consider further restricting the associated type
+   |
+LL | fn bar<T:Trait+Send>() where <T as Trait>::AssocType: Send {
+   |                        +++++++++++++++++++++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-cross-crate-coherence.rs b/src/test/ui/typeck/typeck-default-trait-impl-cross-crate-coherence.rs
new file mode 100644
index 000000000..cc75cd490
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-cross-crate-coherence.rs
@@ -0,0 +1,25 @@
+// aux-build:tdticc_coherence_lib.rs
+#![allow(suspicious_auto_trait_impls)]
+
+// Test that we do not consider associated types to be sendable without
+// some applicable trait bound (and we don't ICE).
+
+#![feature(negative_impls)]
+
+extern crate tdticc_coherence_lib as lib;
+
+use lib::DefaultedTrait;
+
+struct A;
+impl DefaultedTrait for (A,) { } //~ ERROR E0117
+
+struct B;
+impl !DefaultedTrait for (B,) { } //~ ERROR E0117
+
+struct C;
+struct D<T>(T);
+impl DefaultedTrait for Box<C> { } //~ ERROR E0321
+impl DefaultedTrait for lib::Something<C> { } //~ ERROR E0117
+impl DefaultedTrait for D<C> { } // OK
+
+fn main() { }
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-cross-crate-coherence.stderr b/src/test/ui/typeck/typeck-default-trait-impl-cross-crate-coherence.stderr
new file mode 100644
index 000000000..fc3778b79
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-cross-crate-coherence.stderr
@@ -0,0 +1,43 @@
+error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
+  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:14:1
+   |
+LL | impl DefaultedTrait for (A,) { }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^----
+   | |                       |
+   | |                       this is not defined in the current crate because tuples are always foreign
+   | impl doesn't use only types from inside the current crate
+   |
+   = note: define and implement a trait or new type instead
+
+error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
+  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:17:1
+   |
+LL | impl !DefaultedTrait for (B,) { }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^----
+   | |                        |
+   | |                        this is not defined in the current crate because tuples are always foreign
+   | impl doesn't use only types from inside the current crate
+   |
+   = note: define and implement a trait or new type instead
+
+error[E0321]: cross-crate traits with a default impl, like `DefaultedTrait`, can only be implemented for a struct/enum type defined in the current crate
+  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:21:1
+   |
+LL | impl DefaultedTrait for Box<C> { }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait for type in another crate
+
+error[E0117]: only traits defined in the current crate can be implemented for types defined outside of the crate
+  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:22:1
+   |
+LL | impl DefaultedTrait for lib::Something<C> { }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^-----------------
+   | |                       |
+   | |                       `Something` is not defined in the current crate
+   | impl doesn't use only types from inside the current crate
+   |
+   = note: define and implement a trait or new type instead
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0117, E0321.
+For more information about an error, try `rustc --explain E0117`.
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-negation-send.rs b/src/test/ui/typeck/typeck-default-trait-impl-negation-send.rs
new file mode 100644
index 000000000..3a2fc39d4
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-negation-send.rs
@@ -0,0 +1,21 @@
+#![feature(negative_impls)]
+
+struct MySendable {
+   t: *mut u8
+}
+
+unsafe impl Send for MySendable {}
+
+struct MyNotSendable {
+   t: *mut u8
+}
+
+impl !Send for MyNotSendable {}
+
+fn is_send<T: Send>() {}
+
+fn main() {
+    is_send::<MySendable>();
+    is_send::<MyNotSendable>();
+    //~^ ERROR `MyNotSendable` cannot be sent between threads safely
+}
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-negation-send.stderr b/src/test/ui/typeck/typeck-default-trait-impl-negation-send.stderr
new file mode 100644
index 000000000..2ce32990e
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-negation-send.stderr
@@ -0,0 +1,16 @@
+error[E0277]: `MyNotSendable` cannot be sent between threads safely
+  --> $DIR/typeck-default-trait-impl-negation-send.rs:19:15
+   |
+LL |     is_send::<MyNotSendable>();
+   |               ^^^^^^^^^^^^^ `MyNotSendable` cannot be sent between threads safely
+   |
+   = help: the trait `Send` is not implemented for `MyNotSendable`
+note: required by a bound in `is_send`
+  --> $DIR/typeck-default-trait-impl-negation-send.rs:15:15
+   |
+LL | fn is_send<T: Send>() {}
+   |               ^^^^ required by this bound in `is_send`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-negation-sync.rs b/src/test/ui/typeck/typeck-default-trait-impl-negation-sync.rs
new file mode 100644
index 000000000..b9042188a
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-negation-sync.rs
@@ -0,0 +1,41 @@
+#![feature(negative_impls)]
+
+struct Managed;
+impl !Send for Managed {}
+impl !Sync for Managed {}
+
+use std::cell::UnsafeCell;
+
+struct MySync {
+   t: *mut u8
+}
+
+unsafe impl Sync for MySync {}
+
+struct MyNotSync {
+   t: *mut u8
+}
+
+impl !Sync for MyNotSync {}
+
+struct MyTypeWUnsafe {
+   t: UnsafeCell<u8>
+}
+
+struct MyTypeManaged {
+   t: Managed
+}
+
+fn is_sync<T: Sync>() {}
+
+fn main() {
+    is_sync::<MySync>();
+    is_sync::<MyNotSync>();
+    //~^ ERROR `MyNotSync` cannot be shared between threads safely [E0277]
+
+    is_sync::<MyTypeWUnsafe>();
+    //~^ ERROR `UnsafeCell<u8>` cannot be shared between threads safely [E0277]
+
+    is_sync::<MyTypeManaged>();
+    //~^ ERROR `Managed` cannot be shared between threads safely [E0277]
+}
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-negation-sync.stderr b/src/test/ui/typeck/typeck-default-trait-impl-negation-sync.stderr
new file mode 100644
index 000000000..6bb5e1f54
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-negation-sync.stderr
@@ -0,0 +1,52 @@
+error[E0277]: `MyNotSync` cannot be shared between threads safely
+  --> $DIR/typeck-default-trait-impl-negation-sync.rs:33:15
+   |
+LL |     is_sync::<MyNotSync>();
+   |               ^^^^^^^^^ `MyNotSync` cannot be shared between threads safely
+   |
+   = help: the trait `Sync` is not implemented for `MyNotSync`
+note: required by a bound in `is_sync`
+  --> $DIR/typeck-default-trait-impl-negation-sync.rs:29:15
+   |
+LL | fn is_sync<T: Sync>() {}
+   |               ^^^^ required by this bound in `is_sync`
+
+error[E0277]: `UnsafeCell<u8>` cannot be shared between threads safely
+  --> $DIR/typeck-default-trait-impl-negation-sync.rs:36:5
+   |
+LL |     is_sync::<MyTypeWUnsafe>();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^ `UnsafeCell<u8>` cannot be shared between threads safely
+   |
+   = help: within `MyTypeWUnsafe`, the trait `Sync` is not implemented for `UnsafeCell<u8>`
+note: required because it appears within the type `MyTypeWUnsafe`
+  --> $DIR/typeck-default-trait-impl-negation-sync.rs:21:8
+   |
+LL | struct MyTypeWUnsafe {
+   |        ^^^^^^^^^^^^^
+note: required by a bound in `is_sync`
+  --> $DIR/typeck-default-trait-impl-negation-sync.rs:29:15
+   |
+LL | fn is_sync<T: Sync>() {}
+   |               ^^^^ required by this bound in `is_sync`
+
+error[E0277]: `Managed` cannot be shared between threads safely
+  --> $DIR/typeck-default-trait-impl-negation-sync.rs:39:5
+   |
+LL |     is_sync::<MyTypeManaged>();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^ `Managed` cannot be shared between threads safely
+   |
+   = help: within `MyTypeManaged`, the trait `Sync` is not implemented for `Managed`
+note: required because it appears within the type `MyTypeManaged`
+  --> $DIR/typeck-default-trait-impl-negation-sync.rs:25:8
+   |
+LL | struct MyTypeManaged {
+   |        ^^^^^^^^^^^^^
+note: required by a bound in `is_sync`
+  --> $DIR/typeck-default-trait-impl-negation-sync.rs:29:15
+   |
+LL | fn is_sync<T: Sync>() {}
+   |               ^^^^ required by this bound in `is_sync`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-send-param.rs b/src/test/ui/typeck/typeck-default-trait-impl-send-param.rs
new file mode 100644
index 000000000..7948cd101
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-send-param.rs
@@ -0,0 +1,11 @@
+// Test that we do not consider parameter types to be sendable without
+// an explicit trait bound.
+
+fn foo<T>() {
+    is_send::<T>() //~ ERROR E0277
+}
+
+fn is_send<T:Send>() {
+}
+
+fn main() { }
diff --git a/src/test/ui/typeck/typeck-default-trait-impl-send-param.stderr b/src/test/ui/typeck/typeck-default-trait-impl-send-param.stderr
new file mode 100644
index 000000000..887a1ddbb
--- /dev/null
+++ b/src/test/ui/typeck/typeck-default-trait-impl-send-param.stderr
@@ -0,0 +1,19 @@
+error[E0277]: `T` cannot be sent between threads safely
+  --> $DIR/typeck-default-trait-impl-send-param.rs:5:15
+   |
+LL |     is_send::<T>()
+   |               ^ `T` cannot be sent between threads safely
+   |
+note: required by a bound in `is_send`
+  --> $DIR/typeck-default-trait-impl-send-param.rs:8:14
+   |
+LL | fn is_send<T:Send>() {
+   |              ^^^^ required by this bound in `is_send`
+help: consider restricting type parameter `T`
+   |
+LL | fn foo<T: std::marker::Send>() {
+   |         +++++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/typeck/typeck-fn-to-unsafe-fn-ptr.rs b/src/test/ui/typeck/typeck-fn-to-unsafe-fn-ptr.rs
new file mode 100644
index 000000000..1e954f569
--- /dev/null
+++ b/src/test/ui/typeck/typeck-fn-to-unsafe-fn-ptr.rs
@@ -0,0 +1,12 @@
+// run-pass
+// This tests reification from safe function to `unsafe fn` pointer
+
+fn do_nothing() -> () {}
+
+unsafe fn call_unsafe(func: unsafe fn() -> ()) -> () {
+    func()
+}
+
+pub fn main() {
+    unsafe { call_unsafe(do_nothing); }
+}
diff --git a/src/test/ui/typeck/typeck-unsafe-always-share.rs b/src/test/ui/typeck/typeck-unsafe-always-share.rs
new file mode 100644
index 000000000..be87ab172
--- /dev/null
+++ b/src/test/ui/typeck/typeck-unsafe-always-share.rs
@@ -0,0 +1,32 @@
+// Verify that UnsafeCell is *always* !Sync regardless if `T` is sync.
+
+#![feature(negative_impls)]
+
+use std::cell::UnsafeCell;
+use std::marker::Sync;
+
+struct MySync<T> {
+    u: UnsafeCell<T>
+}
+
+struct NoSync;
+impl !Sync for NoSync {}
+
+fn test<T: Sync>(s: T) {}
+
+fn main() {
+    let us = UnsafeCell::new(MySync{u: UnsafeCell::new(0)});
+    test(us);
+    //~^ ERROR `UnsafeCell<MySync<{integer}>>` cannot be shared between threads safely
+
+    let uns = UnsafeCell::new(NoSync);
+    test(uns);
+    //~^ ERROR `UnsafeCell<NoSync>` cannot be shared between threads safely [E0277]
+
+    let ms = MySync{u: uns};
+    test(ms);
+    //~^ ERROR `UnsafeCell<NoSync>` cannot be shared between threads safely [E0277]
+
+    test(NoSync);
+    //~^ ERROR `NoSync` cannot be shared between threads safely [E0277]
+}
diff --git a/src/test/ui/typeck/typeck-unsafe-always-share.stderr b/src/test/ui/typeck/typeck-unsafe-always-share.stderr
new file mode 100644
index 000000000..154e50499
--- /dev/null
+++ b/src/test/ui/typeck/typeck-unsafe-always-share.stderr
@@ -0,0 +1,68 @@
+error[E0277]: `UnsafeCell<MySync<{integer}>>` cannot be shared between threads safely
+  --> $DIR/typeck-unsafe-always-share.rs:19:10
+   |
+LL |     test(us);
+   |     ---- ^^ `UnsafeCell<MySync<{integer}>>` cannot be shared between threads safely
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: the trait `Sync` is not implemented for `UnsafeCell<MySync<{integer}>>`
+note: required by a bound in `test`
+  --> $DIR/typeck-unsafe-always-share.rs:15:12
+   |
+LL | fn test<T: Sync>(s: T) {}
+   |            ^^^^ required by this bound in `test`
+
+error[E0277]: `UnsafeCell<NoSync>` cannot be shared between threads safely
+  --> $DIR/typeck-unsafe-always-share.rs:23:10
+   |
+LL |     test(uns);
+   |     ---- ^^^ `UnsafeCell<NoSync>` cannot be shared between threads safely
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: the trait `Sync` is not implemented for `UnsafeCell<NoSync>`
+note: required by a bound in `test`
+  --> $DIR/typeck-unsafe-always-share.rs:15:12
+   |
+LL | fn test<T: Sync>(s: T) {}
+   |            ^^^^ required by this bound in `test`
+
+error[E0277]: `UnsafeCell<NoSync>` cannot be shared between threads safely
+  --> $DIR/typeck-unsafe-always-share.rs:27:10
+   |
+LL |     test(ms);
+   |     ---- ^^ `UnsafeCell<NoSync>` cannot be shared between threads safely
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: within `MySync<NoSync>`, the trait `Sync` is not implemented for `UnsafeCell<NoSync>`
+note: required because it appears within the type `MySync<NoSync>`
+  --> $DIR/typeck-unsafe-always-share.rs:8:8
+   |
+LL | struct MySync<T> {
+   |        ^^^^^^
+note: required by a bound in `test`
+  --> $DIR/typeck-unsafe-always-share.rs:15:12
+   |
+LL | fn test<T: Sync>(s: T) {}
+   |            ^^^^ required by this bound in `test`
+
+error[E0277]: `NoSync` cannot be shared between threads safely
+  --> $DIR/typeck-unsafe-always-share.rs:30:10
+   |
+LL |     test(NoSync);
+   |     ---- ^^^^^^ `NoSync` cannot be shared between threads safely
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: the trait `Sync` is not implemented for `NoSync`
+note: required by a bound in `test`
+  --> $DIR/typeck-unsafe-always-share.rs:15:12
+   |
+LL | fn test<T: Sync>(s: T) {}
+   |            ^^^^ required by this bound in `test`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/typeck/typeck_type_placeholder_1.rs b/src/test/ui/typeck/typeck_type_placeholder_1.rs
new file mode 100644
index 000000000..ea7aa5285
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_1.rs
@@ -0,0 +1,32 @@
+// run-pass
+
+#![allow(dead_code)]
+// This test checks that the `_` type placeholder works
+// correctly for enabling type inference.
+
+
+struct TestStruct {
+    x: *const isize
+}
+
+unsafe impl Sync for TestStruct {}
+
+static CONSTEXPR: TestStruct = TestStruct{ x: &413 };
+
+
+pub fn main() {
+    let x: Vec<_> = (0..5).collect();
+    let expected: &[usize] = &[0,1,2,3,4];
+    assert_eq!(x, expected);
+
+    let x = (0..5).collect::<Vec<_>>();
+    assert_eq!(x, expected);
+
+    let y: _ = "hello";
+    assert_eq!(y.len(), 5);
+
+    let ptr: &usize = &5;
+    let ptr2 = ptr as *const _;
+
+    assert_eq!(ptr as *const usize as usize, ptr2 as usize);
+}
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.rs b/src/test/ui/typeck/typeck_type_placeholder_item.rs
new file mode 100644
index 000000000..22fedb22d
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.rs
@@ -0,0 +1,222 @@
+// Needed for `type Y = impl Trait<_>` and `type B = _;`
+#![feature(associated_type_defaults)]
+#![feature(type_alias_impl_trait)]
+// This test checks that it is not possible to enable global type
+// inference by using the `_` type placeholder.
+
+fn test() -> _ { 5 }
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+
+fn test2() -> (_, _) { (5, 5) }
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+
+static TEST3: _ = "test";
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+
+static TEST4: _ = 145;
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+
+static TEST5: (_, _) = (1, 2);
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+
+fn test6(_: _) { }
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+
+fn test6_b<T>(_: _, _: T) { }
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+
+fn test6_c<T, K, L, A, B>(_: _, _: (T, K, L, A, B)) { }
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+
+fn test7(x: _) { let _x: usize = x; }
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+
+fn test8(_f: fn() -> _) { }
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+//~^^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+
+struct Test9;
+
+impl Test9 {
+    fn test9(&self) -> _ { () }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+
+    fn test10(&self, _x : _) { }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+}
+
+fn test11(x: &usize) -> &_ {
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+    &x
+}
+
+unsafe fn test12(x: *const usize) -> *const *const _ {
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+    &x
+}
+
+impl Clone for Test9 {
+    fn clone(&self) -> _ { Test9 }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+
+    fn clone_from(&mut self, other: _) { *self = Test9; }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+}
+
+struct Test10 {
+    a: _,
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for structs
+    b: (_, _),
+}
+
+pub fn main() {
+    static A = 42;
+    //~^ ERROR missing type for `static` item
+    static B: _ = 42;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+    static C: Option<_> = Some(42);
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+    fn fn_test() -> _ { 5 }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+
+    fn fn_test2() -> (_, _) { (5, 5) }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+
+    static FN_TEST3: _ = "test";
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+
+    static FN_TEST4: _ = 145;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+
+    static FN_TEST5: (_, _) = (1, 2);
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
+
+    fn fn_test6(_: _) { }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+
+    fn fn_test7(x: _) { let _x: usize = x; }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+
+    fn fn_test8(_f: fn() -> _) { }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    //~^^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+
+    struct FnTest9;
+
+    impl FnTest9 {
+        fn fn_test9(&self) -> _ { () }
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+
+        fn fn_test10(&self, _x : _) { }
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    }
+
+    impl Clone for FnTest9 {
+        fn clone(&self) -> _ { FnTest9 }
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+
+        fn clone_from(&mut self, other: _) { *self = FnTest9; }
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    }
+
+    struct FnTest10 {
+        a: _,
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for structs
+        b: (_, _),
+    }
+
+    fn fn_test11(_: _) -> (_, _) { panic!() }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+    //~| ERROR type annotations needed
+
+    fn fn_test12(x: i32) -> (_, _) { (x, x) }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+
+    fn fn_test13(x: _) -> (i32, _) { (x, x) }
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+}
+
+trait T {
+    fn method_test1(&self, x: _);
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    fn method_test2(&self, x: _) -> _;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    fn method_test3(&self) -> _;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    fn assoc_fn_test1(x: _);
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    fn assoc_fn_test2(x: _) -> _;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    fn assoc_fn_test3() -> _;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+}
+
+struct BadStruct<_>(_);
+//~^ ERROR expected identifier, found reserved identifier `_`
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for structs
+trait BadTrait<_> {}
+//~^ ERROR expected identifier, found reserved identifier `_`
+impl BadTrait<_> for BadStruct<_> {}
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for implementations
+
+fn impl_trait() -> impl BadTrait<_> {
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for opaque types
+    unimplemented!()
+}
+
+struct BadStruct1<_, _>(_);
+//~^ ERROR expected identifier, found reserved identifier `_`
+//~| ERROR expected identifier, found reserved identifier `_`
+//~| ERROR the name `_` is already used
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for structs
+struct BadStruct2<_, T>(_, T);
+//~^ ERROR expected identifier, found reserved identifier `_`
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for structs
+
+type X = Box<_>;
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for type aliases
+
+struct Struct;
+trait Trait<T> {}
+impl Trait<usize> for Struct {}
+type Y = impl Trait<_>;
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for opaque types
+fn foo() -> Y {
+    Struct
+}
+
+trait Qux {
+    type A;
+    type B = _;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
+    const C: _;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+    const D: _ = 42;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+    // type E: _; // FIXME: make the parser propagate the existence of `B`
+    type F: std::ops::Fn(_);
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
+}
+impl Qux for Struct {
+    type A = _;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
+    type B = _;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
+    const C: _;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+    //~| ERROR associated constant in `impl` without body
+    const D: _ = 42;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+}
+
+fn map<T>(_: fn() -> Option<&'static T>) -> Option<T> {
+    None
+}
+
+fn value() -> Option<&'static _> {
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+    Option::<&'static u8>::None
+}
+
+const _: Option<_> = map(value);
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.stderr b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
new file mode 100644
index 000000000..3ea317dfb
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
@@ -0,0 +1,642 @@
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/typeck_type_placeholder_item.rs:154:18
+   |
+LL | struct BadStruct<_>(_);
+   |                  ^ expected identifier, found reserved identifier
+
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/typeck_type_placeholder_item.rs:157:16
+   |
+LL | trait BadTrait<_> {}
+   |                ^ expected identifier, found reserved identifier
+
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/typeck_type_placeholder_item.rs:167:19
+   |
+LL | struct BadStruct1<_, _>(_);
+   |                   ^ expected identifier, found reserved identifier
+
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/typeck_type_placeholder_item.rs:167:22
+   |
+LL | struct BadStruct1<_, _>(_);
+   |                      ^ expected identifier, found reserved identifier
+
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/typeck_type_placeholder_item.rs:172:19
+   |
+LL | struct BadStruct2<_, T>(_, T);
+   |                   ^ expected identifier, found reserved identifier
+
+error: associated constant in `impl` without body
+  --> $DIR/typeck_type_placeholder_item.rs:205:5
+   |
+LL |     const C: _;
+   |     ^^^^^^^^^^-
+   |               |
+   |               help: provide a definition for the constant: `= <expr>;`
+
+error[E0403]: the name `_` is already used for a generic parameter in this item's generic parameters
+  --> $DIR/typeck_type_placeholder_item.rs:167:22
+   |
+LL | struct BadStruct1<_, _>(_);
+   |                   -  ^ already used
+   |                   |
+   |                   first use of `_`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:7:14
+   |
+LL | fn test() -> _ { 5 }
+   |              ^
+   |              |
+   |              not allowed in type signatures
+   |              help: replace with the correct return type: `i32`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:10:16
+   |
+LL | fn test2() -> (_, _) { (5, 5) }
+   |               -^--^-
+   |               ||  |
+   |               ||  not allowed in type signatures
+   |               |not allowed in type signatures
+   |               help: replace with the correct return type: `(i32, i32)`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:13:15
+   |
+LL | static TEST3: _ = "test";
+   |               ^
+   |               |
+   |               not allowed in type signatures
+   |               help: replace with the correct type: `&str`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:16:15
+   |
+LL | static TEST4: _ = 145;
+   |               ^
+   |               |
+   |               not allowed in type signatures
+   |               help: replace with the correct type: `i32`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:19:15
+   |
+LL | static TEST5: (_, _) = (1, 2);
+   |               ^^^^^^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:22:13
+   |
+LL | fn test6(_: _) { }
+   |             ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL | fn test6<T>(_: T) { }
+   |         +++    ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:25:18
+   |
+LL | fn test6_b<T>(_: _, _: T) { }
+   |                  ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL | fn test6_b<T, U>(_: U, _: T) { }
+   |             +++     ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:28:30
+   |
+LL | fn test6_c<T, K, L, A, B>(_: _, _: (T, K, L, A, B)) { }
+   |                              ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL | fn test6_c<T, K, L, A, B, U>(_: U, _: (T, K, L, A, B)) { }
+   |                         +++     ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:31:13
+   |
+LL | fn test7(x: _) { let _x: usize = x; }
+   |             ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL | fn test7<T>(x: T) { let _x: usize = x; }
+   |         +++    ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:34:22
+   |
+LL | fn test8(_f: fn() -> _) { }
+   |                      ^
+   |                      |
+   |                      not allowed in type signatures
+   |                      help: use type parameters instead: `T`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:34:22
+   |
+LL | fn test8(_f: fn() -> _) { }
+   |                      ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL | fn test8<T>(_f: fn() -> T) { }
+   |         +++             ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:48:26
+   |
+LL | fn test11(x: &usize) -> &_ {
+   |                         -^
+   |                         ||
+   |                         |not allowed in type signatures
+   |                         help: replace with the correct return type: `&'static &'static usize`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:53:52
+   |
+LL | unsafe fn test12(x: *const usize) -> *const *const _ {
+   |                                      --------------^
+   |                                      |             |
+   |                                      |             not allowed in type signatures
+   |                                      help: replace with the correct return type: `*const *const usize`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:67:8
+   |
+LL |     a: _,
+   |        ^ not allowed in type signatures
+LL |
+LL |     b: (_, _),
+   |         ^  ^ not allowed in type signatures
+   |         |
+   |         not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL ~ struct Test10<T> {
+LL ~     a: T,
+LL |
+LL ~     b: (T, T),
+   |
+
+error: missing type for `static` item
+  --> $DIR/typeck_type_placeholder_item.rs:73:12
+   |
+LL |     static A = 42;
+   |            ^ help: provide a type for the static variable: `A: i32`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:75:15
+   |
+LL |     static B: _ = 42;
+   |               ^
+   |               |
+   |               not allowed in type signatures
+   |               help: replace with the correct type: `i32`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:77:15
+   |
+LL |     static C: Option<_> = Some(42);
+   |               ^^^^^^^^^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:79:21
+   |
+LL |     fn fn_test() -> _ { 5 }
+   |                     ^
+   |                     |
+   |                     not allowed in type signatures
+   |                     help: replace with the correct return type: `i32`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:82:23
+   |
+LL |     fn fn_test2() -> (_, _) { (5, 5) }
+   |                      -^--^-
+   |                      ||  |
+   |                      ||  not allowed in type signatures
+   |                      |not allowed in type signatures
+   |                      help: replace with the correct return type: `(i32, i32)`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:85:22
+   |
+LL |     static FN_TEST3: _ = "test";
+   |                      ^
+   |                      |
+   |                      not allowed in type signatures
+   |                      help: replace with the correct type: `&str`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:88:22
+   |
+LL |     static FN_TEST4: _ = 145;
+   |                      ^
+   |                      |
+   |                      not allowed in type signatures
+   |                      help: replace with the correct type: `i32`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:91:22
+   |
+LL |     static FN_TEST5: (_, _) = (1, 2);
+   |                      ^^^^^^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:94:20
+   |
+LL |     fn fn_test6(_: _) { }
+   |                    ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn fn_test6<T>(_: T) { }
+   |                +++    ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:97:20
+   |
+LL |     fn fn_test7(x: _) { let _x: usize = x; }
+   |                    ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn fn_test7<T>(x: T) { let _x: usize = x; }
+   |                +++    ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:100:29
+   |
+LL |     fn fn_test8(_f: fn() -> _) { }
+   |                             ^
+   |                             |
+   |                             not allowed in type signatures
+   |                             help: use type parameters instead: `T`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:100:29
+   |
+LL |     fn fn_test8(_f: fn() -> _) { }
+   |                             ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn fn_test8<T>(_f: fn() -> T) { }
+   |                +++             ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:123:12
+   |
+LL |         a: _,
+   |            ^ not allowed in type signatures
+LL |
+LL |         b: (_, _),
+   |             ^  ^ not allowed in type signatures
+   |             |
+   |             not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL ~     struct FnTest10<T> {
+LL ~         a: T,
+LL |
+LL ~         b: (T, T),
+   |
+
+error[E0282]: type annotations needed
+  --> $DIR/typeck_type_placeholder_item.rs:128:18
+   |
+LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
+   |                  ^ cannot infer type
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:128:28
+   |
+LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
+   |                            ^  ^ not allowed in type signatures
+   |                            |
+   |                            not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:132:30
+   |
+LL |     fn fn_test12(x: i32) -> (_, _) { (x, x) }
+   |                             -^--^-
+   |                             ||  |
+   |                             ||  not allowed in type signatures
+   |                             |not allowed in type signatures
+   |                             help: replace with the correct return type: `(i32, i32)`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:135:33
+   |
+LL |     fn fn_test13(x: _) -> (i32, _) { (x, x) }
+   |                           ------^-
+   |                           |     |
+   |                           |     not allowed in type signatures
+   |                           help: replace with the correct return type: `(i32, i32)`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:154:21
+   |
+LL | struct BadStruct<_>(_);
+   |                     ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL | struct BadStruct<T>(T);
+   |                  ~  ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for implementations
+  --> $DIR/typeck_type_placeholder_item.rs:159:15
+   |
+LL | impl BadTrait<_> for BadStruct<_> {}
+   |               ^                ^ not allowed in type signatures
+   |               |
+   |               not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL | impl<T> BadTrait<T> for BadStruct<T> {}
+   |     +++          ~                ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for opaque types
+  --> $DIR/typeck_type_placeholder_item.rs:162:34
+   |
+LL | fn impl_trait() -> impl BadTrait<_> {
+   |                                  ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:167:25
+   |
+LL | struct BadStruct1<_, _>(_);
+   |                         ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL | struct BadStruct1<T, _>(T);
+   |                   ~     ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:172:25
+   |
+LL | struct BadStruct2<_, T>(_, T);
+   |                         ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL | struct BadStruct2<U, T>(U, T);
+   |                   ~     ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for type aliases
+  --> $DIR/typeck_type_placeholder_item.rs:176:14
+   |
+LL | type X = Box<_>;
+   |              ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for opaque types
+  --> $DIR/typeck_type_placeholder_item.rs:182:21
+   |
+LL | type Y = impl Trait<_>;
+   |                     ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:216:31
+   |
+LL | fn value() -> Option<&'static _> {
+   |               ----------------^-
+   |               |               |
+   |               |               not allowed in type signatures
+   |               help: replace with the correct return type: `Option<&'static u8>`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:221:10
+   |
+LL | const _: Option<_> = map(value);
+   |          ^^^^^^^^^
+   |          |
+   |          not allowed in type signatures
+   |          help: replace with the correct type: `Option<u8>`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:140:31
+   |
+LL |     fn method_test1(&self, x: _);
+   |                               ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn method_test1<T>(&self, x: T);
+   |                    +++           ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:142:31
+   |
+LL |     fn method_test2(&self, x: _) -> _;
+   |                               ^     ^ not allowed in type signatures
+   |                               |
+   |                               not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn method_test2<T>(&self, x: T) -> T;
+   |                    +++           ~     ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:144:31
+   |
+LL |     fn method_test3(&self) -> _;
+   |                               ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn method_test3<T>(&self) -> T;
+   |                    +++           ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:146:26
+   |
+LL |     fn assoc_fn_test1(x: _);
+   |                          ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn assoc_fn_test1<T>(x: T);
+   |                      +++    ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:148:26
+   |
+LL |     fn assoc_fn_test2(x: _) -> _;
+   |                          ^     ^ not allowed in type signatures
+   |                          |
+   |                          not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn assoc_fn_test2<T>(x: T) -> T;
+   |                      +++    ~     ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:150:28
+   |
+LL |     fn assoc_fn_test3() -> _;
+   |                            ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn assoc_fn_test3<T>() -> T;
+   |                      +++      ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:190:14
+   |
+LL |     type B = _;
+   |              ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:192:14
+   |
+LL |     const C: _;
+   |              ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:194:14
+   |
+LL |     const D: _ = 42;
+   |              ^
+   |              |
+   |              not allowed in type signatures
+   |              help: replace with the correct type: `i32`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:197:26
+   |
+LL |     type F: std::ops::Fn(_);
+   |                          ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:41:24
+   |
+LL |     fn test9(&self) -> _ { () }
+   |                        ^
+   |                        |
+   |                        not allowed in type signatures
+   |                        help: replace with the correct return type: `()`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:44:27
+   |
+LL |     fn test10(&self, _x : _) { }
+   |                           ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn test10<T>(&self, _x : T) { }
+   |              +++             ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:59:24
+   |
+LL |     fn clone(&self) -> _ { Test9 }
+   |                        ^ not allowed in type signatures
+   |
+help: try replacing `_` with the type in the corresponding trait method signature
+   |
+LL |     fn clone(&self) -> Test9 { Test9 }
+   |                        ~~~~~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:62:37
+   |
+LL |     fn clone_from(&mut self, other: _) { *self = Test9; }
+   |                                     ^ not allowed in type signatures
+   |
+help: try replacing `_` with the type in the corresponding trait method signature
+   |
+LL |     fn clone_from(&mut self, other: &Test9) { *self = Test9; }
+   |                                     ~~~~~~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:107:31
+   |
+LL |         fn fn_test9(&self) -> _ { () }
+   |                               ^
+   |                               |
+   |                               not allowed in type signatures
+   |                               help: replace with the correct return type: `()`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:110:34
+   |
+LL |         fn fn_test10(&self, _x : _) { }
+   |                                  ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |         fn fn_test10<T>(&self, _x : T) { }
+   |                     +++             ~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:115:28
+   |
+LL |         fn clone(&self) -> _ { FnTest9 }
+   |                            ^ not allowed in type signatures
+   |
+help: try replacing `_` with the type in the corresponding trait method signature
+   |
+LL |         fn clone(&self) -> FnTest9 { FnTest9 }
+   |                            ~~~~~~~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:118:41
+   |
+LL |         fn clone_from(&mut self, other: _) { *self = FnTest9; }
+   |                                         ^ not allowed in type signatures
+   |
+help: try replacing `_` with the type in the corresponding trait method signature
+   |
+LL |         fn clone_from(&mut self, other: &FnTest9) { *self = FnTest9; }
+   |                                         ~~~~~~~~
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:201:14
+   |
+LL |     type A = _;
+   |              ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:203:14
+   |
+LL |     type B = _;
+   |              ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:205:14
+   |
+LL |     const C: _;
+   |              ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:208:14
+   |
+LL |     const D: _ = 42;
+   |              ^
+   |              |
+   |              not allowed in type signatures
+   |              help: replace with the correct type: `i32`
+
+error: aborting due to 69 previous errors
+
+Some errors have detailed explanations: E0121, E0282, E0403.
+For more information about an error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item_help.rs b/src/test/ui/typeck/typeck_type_placeholder_item_help.rs
new file mode 100644
index 000000000..c459d8c3c
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_item_help.rs
@@ -0,0 +1,33 @@
+// This test checks that it proper item type will be suggested when
+// using the `_` type placeholder.
+
+fn test1() -> _ { Some(42) }
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+
+const TEST2: _ = 42u32;
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+
+const TEST3: _ = Some(42);
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+
+const TEST4: fn() -> _ = 42;
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for constant items
+
+trait Test5 {
+    const TEST5: _ = 42;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+}
+
+struct Test6;
+
+impl Test6 {
+    const TEST6: _ = 13;
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
+}
+
+pub fn main() {
+    let _: Option<usize> = test1();
+    let _: f64 = test1();
+    let _: Option<i32> = test1();
+}
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr b/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr
new file mode 100644
index 000000000..07a5dbd93
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr
@@ -0,0 +1,60 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item_help.rs:4:15
+   |
+LL | fn test1() -> _ { Some(42) }
+   |               ^
+   |               |
+   |               not allowed in type signatures
+   |               help: replace with the correct return type: `Option<i32>`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item_help.rs:7:14
+   |
+LL | const TEST2: _ = 42u32;
+   |              ^
+   |              |
+   |              not allowed in type signatures
+   |              help: replace with the correct type: `u32`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item_help.rs:10:14
+   |
+LL | const TEST3: _ = Some(42);
+   |              ^
+   |              |
+   |              not allowed in type signatures
+   |              help: replace with the correct type: `Option<i32>`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item_help.rs:13:22
+   |
+LL | const TEST4: fn() -> _ = 42;
+   |                      ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constant items
+  --> $DIR/typeck_type_placeholder_item_help.rs:13:22
+   |
+LL | const TEST4: fn() -> _ = 42;
+   |                      ^ not allowed in type signatures
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item_help.rs:18:18
+   |
+LL |     const TEST5: _ = 42;
+   |                  ^
+   |                  |
+   |                  not allowed in type signatures
+   |                  help: replace with the correct type: `i32`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item_help.rs:25:18
+   |
+LL |     const TEST6: _ = 13;
+   |                  ^
+   |                  |
+   |                  not allowed in type signatures
+   |                  help: replace with the correct type: `i32`
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/typeck_type_placeholder_lifetime_1.rs b/src/test/ui/typeck/typeck_type_placeholder_lifetime_1.rs
new file mode 100644
index 000000000..43e46c5b6
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_lifetime_1.rs
@@ -0,0 +1,11 @@
+// This test checks that the `_` type placeholder does not react
+// badly if put as a lifetime parameter.
+
+struct Foo<'a, T:'a> {
+    r: &'a T
+}
+
+pub fn main() {
+    let c: Foo<_, _> = Foo { r: &5 };
+    //~^ ERROR this struct takes 1 generic argument but 2 generic arguments were supplied
+}
diff --git a/src/test/ui/typeck/typeck_type_placeholder_lifetime_1.stderr b/src/test/ui/typeck/typeck_type_placeholder_lifetime_1.stderr
new file mode 100644
index 000000000..a89c6b85c
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_lifetime_1.stderr
@@ -0,0 +1,17 @@
+error[E0107]: this struct takes 1 generic argument but 2 generic arguments were supplied
+  --> $DIR/typeck_type_placeholder_lifetime_1.rs:9:12
+   |
+LL |     let c: Foo<_, _> = Foo { r: &5 };
+   |            ^^^    - help: remove this generic argument
+   |            |
+   |            expected 1 generic argument
+   |
+note: struct defined here, with 1 generic parameter: `T`
+  --> $DIR/typeck_type_placeholder_lifetime_1.rs:4:8
+   |
+LL | struct Foo<'a, T:'a> {
+   |        ^^^     -
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0107`.
diff --git a/src/test/ui/typeck/typeck_type_placeholder_lifetime_2.rs b/src/test/ui/typeck/typeck_type_placeholder_lifetime_2.rs
new file mode 100644
index 000000000..178b8b122
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_lifetime_2.rs
@@ -0,0 +1,11 @@
+// This test checks that the `_` type placeholder does not react
+// badly if put as a lifetime parameter.
+
+struct Foo<'a, T:'a> {
+    r: &'a T
+}
+
+pub fn main() {
+    let c: Foo<_, usize> = Foo { r: &5 };
+    //~^ ERROR this struct takes 1 generic argument but 2 generic arguments were supplied
+}
diff --git a/src/test/ui/typeck/typeck_type_placeholder_lifetime_2.stderr b/src/test/ui/typeck/typeck_type_placeholder_lifetime_2.stderr
new file mode 100644
index 000000000..f30766bdf
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_lifetime_2.stderr
@@ -0,0 +1,17 @@
+error[E0107]: this struct takes 1 generic argument but 2 generic arguments were supplied
+  --> $DIR/typeck_type_placeholder_lifetime_2.rs:9:12
+   |
+LL |     let c: Foo<_, usize> = Foo { r: &5 };
+   |            ^^^    ----- help: remove this generic argument
+   |            |
+   |            expected 1 generic argument
+   |
+note: struct defined here, with 1 generic parameter: `T`
+  --> $DIR/typeck_type_placeholder_lifetime_2.rs:4:8
+   |
+LL | struct Foo<'a, T:'a> {
+   |        ^^^     -
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0107`.
diff --git a/src/test/ui/typeck/typeck_type_placeholder_mismatch.rs b/src/test/ui/typeck/typeck_type_placeholder_mismatch.rs
new file mode 100644
index 000000000..2f9cfcf8d
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_mismatch.rs
@@ -0,0 +1,27 @@
+// This test checks that genuine type errors with partial
+// type hints are understandable.
+
+use std::marker::PhantomData;
+
+struct Foo<T>(PhantomData<T>);
+struct Bar<U>(PhantomData<U>);
+
+pub fn main() {
+}
+
+fn test1() {
+    let x: Foo<_> = Bar::<usize>(PhantomData);
+    //~^ ERROR mismatched types
+    //~| expected struct `Foo<_>`
+    //~| found struct `Bar<usize>`
+    //~| expected struct `Foo`, found struct `Bar`
+    let y: Foo<usize> = x;
+}
+
+fn test2() {
+    let x: Foo<_> = Bar::<usize>(PhantomData);
+    //~^ ERROR mismatched types
+    //~| expected struct `Foo<_>`
+    //~| found struct `Bar<usize>`
+    //~| expected struct `Foo`, found struct `Bar`
+}
diff --git a/src/test/ui/typeck/typeck_type_placeholder_mismatch.stderr b/src/test/ui/typeck/typeck_type_placeholder_mismatch.stderr
new file mode 100644
index 000000000..867412a24
--- /dev/null
+++ b/src/test/ui/typeck/typeck_type_placeholder_mismatch.stderr
@@ -0,0 +1,25 @@
+error[E0308]: mismatched types
+  --> $DIR/typeck_type_placeholder_mismatch.rs:13:21
+   |
+LL |     let x: Foo<_> = Bar::<usize>(PhantomData);
+   |            ------   ^^^^^^^^^^^^^^^^^^^^^^^^^ expected struct `Foo`, found struct `Bar`
+   |            |
+   |            expected due to this
+   |
+   = note: expected struct `Foo<_>`
+              found struct `Bar<usize>`
+
+error[E0308]: mismatched types
+  --> $DIR/typeck_type_placeholder_mismatch.rs:22:21
+   |
+LL |     let x: Foo<_> = Bar::<usize>(PhantomData);
+   |            ------   ^^^^^^^^^^^^^^^^^^^^^^^^^ expected struct `Foo`, found struct `Bar`
+   |            |
+   |            expected due to this
+   |
+   = note: expected struct `Foo<_>`
+              found struct `Bar<usize>`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeck/ufcs-type-params.rs b/src/test/ui/typeck/ufcs-type-params.rs
new file mode 100644
index 000000000..eee2b55b2
--- /dev/null
+++ b/src/test/ui/typeck/ufcs-type-params.rs
@@ -0,0 +1,15 @@
+// run-pass
+// pretty-expanded FIXME #23616
+
+trait Foo<T> {
+    fn get(&self) -> T;
+}
+
+impl Foo<i32> for i32 {
+    fn get(&self) -> i32 { *self }
+}
+
+fn main() {
+    let x: i32 = 1;
+    Foo::<i32>::get(&x);
+}
diff --git a/src/test/ui/typeck/unify-return-ty.rs b/src/test/ui/typeck/unify-return-ty.rs
new file mode 100644
index 000000000..da1d82e89
--- /dev/null
+++ b/src/test/ui/typeck/unify-return-ty.rs
@@ -0,0 +1,16 @@
+// run-pass
+// Tests that the tail expr in null() has its type
+// unified with the type *T, and so the type variable
+// in that type gets resolved.
+
+// pretty-expanded FIXME #23616
+
+use std::mem;
+
+fn null<T>() -> *const T {
+    unsafe {
+        mem::transmute(0_usize)
+    }
+}
+
+pub fn main() { null::<isize>(); }
diff --git a/src/test/ui/typeck/while-loop-block-cond.rs b/src/test/ui/typeck/while-loop-block-cond.rs
new file mode 100644
index 000000000..929759766
--- /dev/null
+++ b/src/test/ui/typeck/while-loop-block-cond.rs
@@ -0,0 +1,4 @@
+fn main() {
+    while {} {}
+    //~^ ERROR mismatched types [E0308]
+}
diff --git a/src/test/ui/typeck/while-loop-block-cond.stderr b/src/test/ui/typeck/while-loop-block-cond.stderr
new file mode 100644
index 000000000..598273af9
--- /dev/null
+++ b/src/test/ui/typeck/while-loop-block-cond.stderr
@@ -0,0 +1,9 @@
+error[E0308]: mismatched types
+  --> $DIR/while-loop-block-cond.rs:2:11
+   |
+LL |     while {} {}
+   |           ^^ expected `bool`, found `()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typeid-intrinsic.rs b/src/test/ui/typeid-intrinsic.rs
new file mode 100644
index 000000000..5bc4e0c21
--- /dev/null
+++ b/src/test/ui/typeid-intrinsic.rs
@@ -0,0 +1,97 @@
+// run-pass
+
+#![allow(deprecated)]
+// aux-build:typeid-intrinsic-aux1.rs
+// aux-build:typeid-intrinsic-aux2.rs
+
+#![feature(core_intrinsics)]
+
+extern crate typeid_intrinsic_aux1 as other1;
+extern crate typeid_intrinsic_aux2 as other2;
+
+use std::hash::{SipHasher, Hasher, Hash};
+use std::any::TypeId;
+
+struct A;
+struct Test;
+
+pub fn main() {
+    assert_eq!(TypeId::of::<other1::A>(), other1::id_A());
+    assert_eq!(TypeId::of::<other1::B>(), other1::id_B());
+    assert_eq!(TypeId::of::<other1::C>(), other1::id_C());
+    assert_eq!(TypeId::of::<other1::D>(), other1::id_D());
+    assert_eq!(TypeId::of::<other1::E>(), other1::id_E());
+    assert_eq!(TypeId::of::<other1::F>(), other1::id_F());
+    assert_eq!(TypeId::of::<other1::G>(), other1::id_G());
+    assert_eq!(TypeId::of::<other1::H>(), other1::id_H());
+    assert_eq!(TypeId::of::<other1::I>(), other1::id_I());
+
+    assert_eq!(TypeId::of::<other2::A>(), other2::id_A());
+    assert_eq!(TypeId::of::<other2::B>(), other2::id_B());
+    assert_eq!(TypeId::of::<other2::C>(), other2::id_C());
+    assert_eq!(TypeId::of::<other2::D>(), other2::id_D());
+    assert_eq!(TypeId::of::<other2::E>(), other2::id_E());
+    assert_eq!(TypeId::of::<other2::F>(), other2::id_F());
+    assert_eq!(TypeId::of::<other2::G>(), other2::id_G());
+    assert_eq!(TypeId::of::<other2::H>(), other2::id_H());
+    assert_eq!(TypeId::of::<other1::I>(), other2::id_I());
+
+    assert_eq!(other1::id_F(), other2::id_F());
+    assert_eq!(other1::id_G(), other2::id_G());
+    assert_eq!(other1::id_H(), other2::id_H());
+    assert_eq!(other1::id_I(), other2::id_I());
+
+    assert_eq!(TypeId::of::<isize>(), other2::foo::<isize>());
+    assert_eq!(TypeId::of::<isize>(), other1::foo::<isize>());
+    assert_eq!(other2::foo::<isize>(), other1::foo::<isize>());
+    assert_eq!(TypeId::of::<A>(), other2::foo::<A>());
+    assert_eq!(TypeId::of::<A>(), other1::foo::<A>());
+    assert_eq!(other2::foo::<A>(), other1::foo::<A>());
+
+    // sanity test of TypeId
+    let (a, b, c) = (TypeId::of::<usize>(), TypeId::of::<&'static str>(),
+                     TypeId::of::<Test>());
+    let (d, e, f) = (TypeId::of::<usize>(), TypeId::of::<&'static str>(),
+                     TypeId::of::<Test>());
+
+    assert!(a != b);
+    assert!(a != c);
+    assert!(b != c);
+
+    assert_eq!(a, d);
+    assert_eq!(b, e);
+    assert_eq!(c, f);
+
+    // check it has a hash
+    let (a, b) = (TypeId::of::<usize>(), TypeId::of::<usize>());
+
+    let mut s1 = SipHasher::new();
+    a.hash(&mut s1);
+    let mut s2 = SipHasher::new();
+    b.hash(&mut s2);
+
+    assert_eq!(s1.finish(), s2.finish());
+
+    // Check projections
+
+    assert_eq!(TypeId::of::<other1::I32Iterator>(), other1::id_i32_iterator());
+    assert_eq!(TypeId::of::<other1::U32Iterator>(), other1::id_u32_iterator());
+    assert_eq!(other1::id_i32_iterator(), other2::id_i32_iterator());
+    assert_eq!(other1::id_u32_iterator(), other2::id_u32_iterator());
+    assert_ne!(other1::id_i32_iterator(), other1::id_u32_iterator());
+    assert_ne!(TypeId::of::<other1::I32Iterator>(), TypeId::of::<other1::U32Iterator>());
+
+    // Check fn pointer against collisions
+    assert_ne!(
+        TypeId::of::<fn(fn(A) -> A) -> A>(),
+        TypeId::of::<fn(fn() -> A, A) -> A>()
+    );
+    assert_ne!(
+        TypeId::of::<for<'a> fn(&'a i32) -> &'a i32>(),
+        TypeId::of::<for<'a> fn(&'a i32) -> &'static i32>()
+    );
+    assert_ne!(
+        TypeId::of::<for<'a, 'b> fn(&'a i32, &'b i32) -> &'a i32>(),
+        TypeId::of::<for<'a, 'b> fn(&'b i32, &'a i32) -> &'a i32>()
+    );
+}
diff --git a/src/test/ui/typeof/type_mismatch.rs b/src/test/ui/typeof/type_mismatch.rs
new file mode 100644
index 000000000..3f8339fa5
--- /dev/null
+++ b/src/test/ui/typeof/type_mismatch.rs
@@ -0,0 +1,9 @@
+// Test that using typeof results in the correct type mismatch errors instead of always assuming
+// `usize`, in addition to the pre-existing "typeof is reserved and unimplemented" error
+fn main() {
+    const a: u8 = 1;
+    let b: typeof(a) = 1i8;
+    //~^ ERROR `typeof` is a reserved keyword but unimplemented
+    //~| ERROR mismatched types
+    //~| expected `u8`, found `i8`
+}
diff --git a/src/test/ui/typeof/type_mismatch.stderr b/src/test/ui/typeof/type_mismatch.stderr
new file mode 100644
index 000000000..e75214cd3
--- /dev/null
+++ b/src/test/ui/typeof/type_mismatch.stderr
@@ -0,0 +1,28 @@
+error[E0516]: `typeof` is a reserved keyword but unimplemented
+  --> $DIR/type_mismatch.rs:5:12
+   |
+LL |     let b: typeof(a) = 1i8;
+   |            ^^^^^^^^^ reserved keyword
+   |
+help: consider replacing `typeof(...)` with an actual type
+   |
+LL |     let b: u8 = 1i8;
+   |            ~~
+
+error[E0308]: mismatched types
+  --> $DIR/type_mismatch.rs:5:24
+   |
+LL |     let b: typeof(a) = 1i8;
+   |            ---------   ^^^ expected `u8`, found `i8`
+   |            |
+   |            expected due to this
+   |
+help: change the type of the numeric literal from `i8` to `u8`
+   |
+LL |     let b: typeof(a) = 1u8;
+   |                         ~~
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0308, E0516.
+For more information about an error, try `rustc --explain E0308`.
diff --git a/src/test/ui/typestate-multi-decl.rs b/src/test/ui/typestate-multi-decl.rs
new file mode 100644
index 000000000..9f9416205
--- /dev/null
+++ b/src/test/ui/typestate-multi-decl.rs
@@ -0,0 +1,7 @@
+// run-pass
+
+pub fn main() {
+    let (x, y) = (10, 20);
+    let z = x + y;
+    assert_eq!(z, 30);
+}