Merging upstream version 1.71.1+dfsg1.

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

44 files changed, 484 insertions, 264 deletions

diff --git a/tests/ui/impl-trait/arg-position-impl-trait-too-long.rs b/tests/ui/impl-trait/arg-position-impl-trait-too-long.rs
new file mode 100644
index 000000000..8ef9281c9
--- /dev/null
+++ b/tests/ui/impl-trait/arg-position-impl-trait-too-long.rs
@@ -0,0 +1,22 @@
+struct Header;
+struct EntryMetadata;
+struct Entry<A, B>(A, B);
+
+trait Tr {
+    type EncodedKey;
+    type EncodedValue;
+}
+
+fn test<C: Tr, R>(
+    // This APIT is long, however we shouldn't render the type name with a newline in it.
+    y: impl FnOnce(
+        &mut Header,
+        &mut [EntryMetadata],
+        &mut [Entry<C::EncodedKey, C::EncodedValue>]
+    ) -> R,
+) {
+    let () = y;
+    //~^ ERROR mismatched types
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/arg-position-impl-trait-too-long.stderr b/tests/ui/impl-trait/arg-position-impl-trait-too-long.stderr
new file mode 100644
index 000000000..40446a3d3
--- /dev/null
+++ b/tests/ui/impl-trait/arg-position-impl-trait-too-long.stderr
@@ -0,0 +1,22 @@
+error[E0308]: mismatched types
+  --> $DIR/arg-position-impl-trait-too-long.rs:18:9
+   |
+LL |       y: impl FnOnce(
+   |  ________-
+LL | |         &mut Header,
+LL | |         &mut [EntryMetadata],
+LL | |         &mut [Entry<C::EncodedKey, C::EncodedValue>]
+LL | |     ) -> R,
+   | |__________- this type parameter
+LL |   ) {
+LL |       let () = y;
+   |           ^^   - this expression has type `impl FnOnce(&mut Header, &mut [EntryMetadata], &mut [Entry<C::EncodedKey, C::EncodedValue>]) -> R`
+   |           |
+   |           expected type parameter `impl FnOnce(&mut Header, &mut [EntryMetadata], &mut [Entry<C::EncodedKey, C::EncodedValue>]) -> R`, found `()`
+   |
+   = note: expected type parameter `impl FnOnce(&mut Header, &mut [EntryMetadata], &mut [Entry<C::EncodedKey, C::EncodedValue>]) -> R`
+                   found unit type `()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/impl-trait/auto-trait-leak.stderr b/tests/ui/impl-trait/auto-trait-leak.stderr
index e6c750d0e..aa4ee75bb 100644
--- a/tests/ui/impl-trait/auto-trait-leak.stderr
+++ b/tests/ui/impl-trait/auto-trait-leak.stderr
@@ -9,7 +9,7 @@ note: ...which requires borrow-checking `cycle1`...
    |
 LL | fn cycle1() -> impl Clone {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires processing MIR for `cycle1`...
+note: ...which requires promoting constants in MIR for `cycle1`...
   --> $DIR/auto-trait-leak.rs:12:1
    |
 LL | fn cycle1() -> impl Clone {
@@ -55,7 +55,7 @@ note: ...which requires borrow-checking `cycle2`...
    |
 LL | fn cycle2() -> impl Clone {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires processing MIR for `cycle2`...
+note: ...which requires promoting constants in MIR for `cycle2`...
   --> $DIR/auto-trait-leak.rs:19:1
    |
 LL | fn cycle2() -> impl Clone {
diff --git a/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.rs b/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.rs
index cbf1daabe..af368203d 100644
--- a/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.rs
+++ b/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.rs
@@ -26,7 +26,7 @@ fn bax() -> dyn Trait { //~ ERROR E0746
     if true {
         Struct
     } else {
-        42 //~ ERROR `if` and `else` have incompatible types
+        42
     }
 }
 fn bam() -> Box<dyn Trait> {
diff --git a/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr b/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr
index dc1e40ea5..ed9261d0d 100644
--- a/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr
+++ b/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr
@@ -46,11 +46,10 @@ error[E0746]: return type cannot have an unboxed trait object
 LL | fn bap() -> Trait { Struct }
    |             ^^^^^ doesn't have a size known at compile-time
    |
-   = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
-help: use `impl Trait` as the return type, as all return paths are of type `Struct`, which implements `Trait`
+help: box the return type, and wrap all of the returned values in `Box::new`
    |
-LL | fn bap() -> impl Trait { Struct }
-   |             ~~~~~~~~~~
+LL | fn bap() -> Box<Trait> { Box::new(Struct) }
+   |             ++++     +   +++++++++      +
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:15:13
@@ -58,11 +57,14 @@ error[E0746]: return type cannot have an unboxed trait object
 LL | fn ban() -> dyn Trait { Struct }
    |             ^^^^^^^^^ doesn't have a size known at compile-time
    |
-   = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
-help: use `impl Trait` as the return type, as all return paths are of type `Struct`, which implements `Trait`
+help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
    |
 LL | fn ban() -> impl Trait { Struct }
-   |             ~~~~~~~~~~
+   |             ~~~~
+help: box the return type, and wrap all of the returned values in `Box::new`
+   |
+LL | fn ban() -> Box<dyn Trait> { Box::new(Struct) }
+   |             ++++         +   +++++++++      +
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:17:13
@@ -70,14 +72,14 @@ error[E0746]: return type cannot have an unboxed trait object
 LL | fn bak() -> dyn Trait { unimplemented!() }
    |             ^^^^^^^^^ doesn't have a size known at compile-time
    |
-help: use `impl Trait` as the return type if all return paths have the same type but you want to expose only the trait in the signature
+help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
    |
 LL | fn bak() -> impl Trait { unimplemented!() }
-   |             ~~~~~~~~~~
-help: use a boxed trait object if all return paths implement trait `Trait`
+   |             ~~~~
+help: box the return type, and wrap all of the returned values in `Box::new`
    |
-LL | fn bak() -> Box<dyn Trait> { unimplemented!() }
-   |             ++++         +
+LL | fn bak() -> Box<dyn Trait> { Box::new(unimplemented!()) }
+   |             ++++         +   +++++++++                +
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:19:13
@@ -85,34 +87,18 @@ error[E0746]: return type cannot have an unboxed trait object
 LL | fn bal() -> dyn Trait {
    |             ^^^^^^^^^ doesn't have a size known at compile-time
    |
-   = note: for information on trait objects, see <https://doc.rust-lang.org/book/ch17-02-trait-objects.html#using-trait-objects-that-allow-for-values-of-different-types>
-   = note: if all the returned values were of the same type you could use `impl Trait` as the return type
-   = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
-   = note: you can create a new `enum` with a variant for each returned type
-help: return a boxed trait object instead
+help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
    |
-LL | fn bal() -> Box<dyn Trait> {
-   |             ++++         +
-help: ... and box this value
+LL | fn bal() -> impl Trait {
+   |             ~~~~
+help: box the return type, and wrap all of the returned values in `Box::new`
    |
-LL |         return Box::new(Struct);
-   |                +++++++++      +
-help: ... and box this value
+LL ~ fn bal() -> Box<dyn Trait> {
+LL |     if true {
+LL ~         return Box::new(Struct);
+LL |     }
+LL ~     Box::new(42)
    |
-LL |     Box::new(42)
-   |     +++++++++  +
-
-error[E0308]: `if` and `else` have incompatible types
-  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:29:9
-   |
-LL | /     if true {
-LL | |         Struct
-   | |         ------ expected because of this
-LL | |     } else {
-LL | |         42
-   | |         ^^ expected `Struct`, found integer
-LL | |     }
-   | |_____- `if` and `else` have incompatible types
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:25:13
@@ -120,22 +106,18 @@ error[E0746]: return type cannot have an unboxed trait object
 LL | fn bax() -> dyn Trait {
    |             ^^^^^^^^^ doesn't have a size known at compile-time
    |
-   = note: for information on trait objects, see <https://doc.rust-lang.org/book/ch17-02-trait-objects.html#using-trait-objects-that-allow-for-values-of-different-types>
-   = note: if all the returned values were of the same type you could use `impl Trait` as the return type
-   = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
-   = note: you can create a new `enum` with a variant for each returned type
-help: return a boxed trait object instead
+help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
    |
-LL | fn bax() -> Box<dyn Trait> {
-   |             ++++         +
-help: ... and box this value
+LL | fn bax() -> impl Trait {
+   |             ~~~~
+help: box the return type, and wrap all of the returned values in `Box::new`
    |
-LL |         Box::new(Struct)
-   |         +++++++++      +
-help: ... and box this value
+LL ~ fn bax() -> Box<dyn Trait> {
+LL |     if true {
+LL ~         Box::new(Struct)
+LL |     } else {
+LL ~         Box::new(42)
    |
-LL |         Box::new(42)
-   |         +++++++++  +
 
 error[E0308]: mismatched types
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:34:16
@@ -279,11 +261,18 @@ error[E0746]: return type cannot have an unboxed trait object
 LL | fn bat() -> dyn Trait {
    |             ^^^^^^^^^ doesn't have a size known at compile-time
    |
-   = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
-help: use `impl Trait` as the return type, as all return paths are of type `{integer}`, which implements `Trait`
+help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
    |
 LL | fn bat() -> impl Trait {
-   |             ~~~~~~~~~~
+   |             ~~~~
+help: box the return type, and wrap all of the returned values in `Box::new`
+   |
+LL ~ fn bat() -> Box<dyn Trait> {
+LL |     if true {
+LL ~         return Box::new(0);
+LL |     }
+LL ~     Box::new(42)
+   |
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:66:13
@@ -291,13 +280,20 @@ error[E0746]: return type cannot have an unboxed trait object
 LL | fn bay() -> dyn Trait {
    |             ^^^^^^^^^ doesn't have a size known at compile-time
    |
-   = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
-help: use `impl Trait` as the return type, as all return paths are of type `{integer}`, which implements `Trait`
+help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
    |
 LL | fn bay() -> impl Trait {
-   |             ~~~~~~~~~~
+   |             ~~~~
+help: box the return type, and wrap all of the returned values in `Box::new`
+   |
+LL ~ fn bay() -> Box<dyn Trait> {
+LL |     if true {
+LL ~         Box::new(0)
+LL |     } else {
+LL ~         Box::new(42)
+   |
 
-error: aborting due to 20 previous errors
+error: aborting due to 19 previous errors
 
 Some errors have detailed explanations: E0277, E0308, E0746.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/impl-trait/extra-impl-in-trait-impl.fixed b/tests/ui/impl-trait/extra-impl-in-trait-impl.fixed
new file mode 100644
index 000000000..cd4f2610d
--- /dev/null
+++ b/tests/ui/impl-trait/extra-impl-in-trait-impl.fixed
@@ -0,0 +1,19 @@
+// run-rustfix
+
+struct S<T>(T);
+struct S2;
+
+impl<T: Default> Default for S<T> {
+    //~^ ERROR: unexpected `impl` keyword
+    //~| HELP: remove the extra `impl`
+    fn default() -> Self { todo!() }
+}
+
+impl Default for S2 {
+    //~^ ERROR: unexpected `impl` keyword
+    //~| HELP: remove the extra `impl`
+    fn default() -> Self { todo!() }
+}
+
+
+fn main() {}
diff --git a/tests/ui/impl-trait/extra-impl-in-trait-impl.rs b/tests/ui/impl-trait/extra-impl-in-trait-impl.rs
new file mode 100644
index 000000000..024b703e6
--- /dev/null
+++ b/tests/ui/impl-trait/extra-impl-in-trait-impl.rs
@@ -0,0 +1,19 @@
+// run-rustfix
+
+struct S<T>(T);
+struct S2;
+
+impl<T: Default> impl Default for S<T> {
+    //~^ ERROR: unexpected `impl` keyword
+    //~| HELP: remove the extra `impl`
+    fn default() -> Self { todo!() }
+}
+
+impl impl Default for S2 {
+    //~^ ERROR: unexpected `impl` keyword
+    //~| HELP: remove the extra `impl`
+    fn default() -> Self { todo!() }
+}
+
+
+fn main() {}
diff --git a/tests/ui/impl-trait/extra-impl-in-trait-impl.stderr b/tests/ui/impl-trait/extra-impl-in-trait-impl.stderr
new file mode 100644
index 000000000..5aafc8b64
--- /dev/null
+++ b/tests/ui/impl-trait/extra-impl-in-trait-impl.stderr
@@ -0,0 +1,26 @@
+error: unexpected `impl` keyword
+  --> $DIR/extra-impl-in-trait-impl.rs:6:18
+   |
+LL | impl<T: Default> impl Default for S<T> {
+   |                  ^^^^^ help: remove the extra `impl`
+   |
+note: this is parsed as an `impl Trait` type, but a trait is expected at this position
+  --> $DIR/extra-impl-in-trait-impl.rs:6:18
+   |
+LL | impl<T: Default> impl Default for S<T> {
+   |                  ^^^^^^^^^^^^
+
+error: unexpected `impl` keyword
+  --> $DIR/extra-impl-in-trait-impl.rs:12:6
+   |
+LL | impl impl Default for S2 {
+   |      ^^^^^ help: remove the extra `impl`
+   |
+note: this is parsed as an `impl Trait` type, but a trait is expected at this position
+  --> $DIR/extra-impl-in-trait-impl.rs:12:6
+   |
+LL | impl impl Default for S2 {
+   |      ^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/impl-trait/in-assoc-type-unconstrained.rs b/tests/ui/impl-trait/in-assoc-type-unconstrained.rs
new file mode 100644
index 000000000..c395b4195
--- /dev/null
+++ b/tests/ui/impl-trait/in-assoc-type-unconstrained.rs
@@ -0,0 +1,27 @@
+#![feature(impl_trait_in_assoc_type)]
+
+mod compare_ty {
+    trait Trait {
+        type Ty: IntoIterator<Item = ()>;
+    }
+    impl Trait for () {
+        type Ty = Option<impl Sized>;
+        //~^ ERROR: unconstrained opaque type
+        //~| ERROR: type mismatch resolving `<Option<<() as Trait>::Ty::{opaque#0}> as IntoIterator>::Item == ()`
+    }
+}
+
+mod compare_method {
+    trait Trait {
+        type Ty;
+        fn method() -> Self::Ty;
+    }
+    impl Trait for () {
+        type Ty = impl Sized;
+        //~^ ERROR: unconstrained opaque type
+        fn method() -> () {}
+        //~^ ERROR: method `method` has an incompatible type for trait
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/in-assoc-type-unconstrained.stderr b/tests/ui/impl-trait/in-assoc-type-unconstrained.stderr
new file mode 100644
index 000000000..1097cd0f4
--- /dev/null
+++ b/tests/ui/impl-trait/in-assoc-type-unconstrained.stderr
@@ -0,0 +1,59 @@
+error[E0271]: type mismatch resolving `<Option<<() as Trait>::Ty::{opaque#0}> as IntoIterator>::Item == ()`
+  --> $DIR/in-assoc-type-unconstrained.rs:8:19
+   |
+LL |         type Ty = Option<impl Sized>;
+   |                   ^^^^^^^^^^^^^^^^^^ expected `()`, found opaque type
+   |
+   = note: expected unit type `()`
+            found opaque type `<() as compare_ty::Trait>::Ty::{opaque#0}`
+note: required by a bound in `compare_ty::Trait::Ty`
+  --> $DIR/in-assoc-type-unconstrained.rs:5:31
+   |
+LL |         type Ty: IntoIterator<Item = ()>;
+   |                               ^^^^^^^^^ required by this bound in `Trait::Ty`
+
+error: unconstrained opaque type
+  --> $DIR/in-assoc-type-unconstrained.rs:8:26
+   |
+LL |         type Ty = Option<impl Sized>;
+   |                          ^^^^^^^^^^
+   |
+   = note: `Ty` must be used in combination with a concrete type within the same impl
+
+error[E0053]: method `method` has an incompatible type for trait
+  --> $DIR/in-assoc-type-unconstrained.rs:22:24
+   |
+LL |         type Ty = impl Sized;
+   |                   ---------- the expected opaque type
+LL |
+LL |         fn method() -> () {}
+   |                        ^^
+   |                        |
+   |                        expected opaque type, found `()`
+   |                        help: change the output type to match the trait: `<() as compare_method::Trait>::Ty`
+   |
+note: type in trait
+  --> $DIR/in-assoc-type-unconstrained.rs:17:24
+   |
+LL |         fn method() -> Self::Ty;
+   |                        ^^^^^^^^
+   = note: expected signature `fn() -> <() as compare_method::Trait>::Ty`
+              found signature `fn()`
+note: this item must have the opaque type in its signature in order to be able to register hidden types
+  --> $DIR/in-assoc-type-unconstrained.rs:22:9
+   |
+LL |         fn method() -> () {}
+   |         ^^^^^^^^^^^^^^^^^
+
+error: unconstrained opaque type
+  --> $DIR/in-assoc-type-unconstrained.rs:20:19
+   |
+LL |         type Ty = impl Sized;
+   |                   ^^^^^^^^^^
+   |
+   = note: `Ty` must be used in combination with a concrete type within the same impl
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0053, E0271.
+For more information about an error, try `rustc --explain E0053`.
diff --git a/tests/ui/impl-trait/in-assoc-type.rs b/tests/ui/impl-trait/in-assoc-type.rs
new file mode 100644
index 000000000..36c54bdd6
--- /dev/null
+++ b/tests/ui/impl-trait/in-assoc-type.rs
@@ -0,0 +1,21 @@
+#![feature(impl_trait_in_assoc_type)]
+
+trait Foo<T> {
+    type Bar;
+    fn foo(&self) -> <Self as Foo<()>>::Bar
+    where
+        Self: Foo<()>;
+}
+
+impl Foo<()> for () {
+    type Bar = impl std::fmt::Debug;
+    fn foo(&self) -> Self::Bar {}
+}
+
+impl Foo<i32> for () {
+    type Bar = u32;
+    fn foo(&self) -> <Self as Foo<()>>::Bar {}
+    //~^ ERROR: mismatched types
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/in-assoc-type.stderr b/tests/ui/impl-trait/in-assoc-type.stderr
new file mode 100644
index 000000000..f0a272dc2
--- /dev/null
+++ b/tests/ui/impl-trait/in-assoc-type.stderr
@@ -0,0 +1,22 @@
+error[E0308]: mismatched types
+  --> $DIR/in-assoc-type.rs:17:22
+   |
+LL |     type Bar = impl std::fmt::Debug;
+   |                -------------------- the expected opaque type
+...
+LL |     fn foo(&self) -> <Self as Foo<()>>::Bar {}
+   |        ---           ^^^^^^^^^^^^^^^^^^^^^^ expected opaque type, found `()`
+   |        |
+   |        implicitly returns `()` as its body has no tail or `return` expression
+   |
+   = note: expected opaque type `<() as Foo<()>>::Bar`
+                found unit type `()`
+note: this item must have the opaque type in its signature in order to be able to register hidden types
+  --> $DIR/in-assoc-type.rs:17:5
+   |
+LL |     fn foo(&self) -> <Self as Foo<()>>::Bar {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/impl-trait/in-trait/auxiliary/rpitit.rs b/tests/ui/impl-trait/in-trait/auxiliary/rpitit.rs
index ffeabe5c2..776006124 100644
--- a/tests/ui/impl-trait/in-trait/auxiliary/rpitit.rs
+++ b/tests/ui/impl-trait/in-trait/auxiliary/rpitit.rs
@@ -5,10 +5,10 @@
 use std::ops::Deref;
 
 pub trait Foo {
-    fn bar() -> impl Deref<Target = impl Sized>;
+    fn bar(self) -> impl Deref<Target = impl Sized>;
 }
 
 pub struct Foreign;
 impl Foo for Foreign {
-    fn bar() -> &'static () { &() }
+    fn bar(self) -> &'static () { &() }
 }
diff --git a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.current.stderr b/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.current.stderr
deleted file mode 100644
index 05c025cc1..000000000
--- a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.current.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/box-coerce-span-in-default.rs:5:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.next.stderr b/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.next.stderr
deleted file mode 100644
index 05c025cc1..000000000
--- a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.next.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/box-coerce-span-in-default.rs:5:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.rs b/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.rs
index 163bb4fcf..f5290a5f4 100644
--- a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.rs
+++ b/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.rs
@@ -3,7 +3,6 @@
 // revisions: current next
 
 #![feature(return_position_impl_trait_in_trait)]
-//~^ WARN the feature `return_position_impl_trait_in_trait` is incomplete
 
 struct TestA {}
 struct TestB {}
diff --git a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.current.stderr b/tests/ui/impl-trait/in-trait/default-method-binder-shifting.current.stderr
deleted file mode 100644
index a0c0589b9..000000000
--- a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.current.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-method-binder-shifting.rs:5:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.next.stderr b/tests/ui/impl-trait/in-trait/default-method-binder-shifting.next.stderr
deleted file mode 100644
index a0c0589b9..000000000
--- a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.next.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-method-binder-shifting.rs:5:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.rs b/tests/ui/impl-trait/in-trait/default-method-binder-shifting.rs
index de82544f2..187039f44 100644
--- a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.rs
+++ b/tests/ui/impl-trait/in-trait/default-method-binder-shifting.rs
@@ -3,7 +3,6 @@
 // revisions: current next
 
 #![feature(return_position_impl_trait_in_trait)]
-//~^ WARN the feature `return_position_impl_trait_in_trait` is incomplete
 
 trait Trait {
     type Type;
diff --git a/tests/ui/impl-trait/in-trait/default-method-constraint.current.stderr b/tests/ui/impl-trait/in-trait/default-method-constraint.current.stderr
deleted file mode 100644
index 7bb79911f..000000000
--- a/tests/ui/impl-trait/in-trait/default-method-constraint.current.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-method-constraint.rs:7:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/default-method-constraint.next.stderr b/tests/ui/impl-trait/in-trait/default-method-constraint.next.stderr
deleted file mode 100644
index 7bb79911f..000000000
--- a/tests/ui/impl-trait/in-trait/default-method-constraint.next.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-method-constraint.rs:7:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/default-method-constraint.rs b/tests/ui/impl-trait/in-trait/default-method-constraint.rs
index e85fe3c86..4f0bf2e7d 100644
--- a/tests/ui/impl-trait/in-trait/default-method-constraint.rs
+++ b/tests/ui/impl-trait/in-trait/default-method-constraint.rs
@@ -5,7 +5,6 @@
 // This didn't work in the previous default RPITIT method hack attempt
 
 #![feature(return_position_impl_trait_in_trait)]
-//~^ WARN the feature `return_position_impl_trait_in_trait` is incomplete
 
 trait Foo {
     fn bar(x: bool) -> impl Sized {
diff --git a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.current.stderr b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.current.stderr
index b8a793e1a..d4d0124a6 100644
--- a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.current.stderr
+++ b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.current.stderr
@@ -1,14 +1,5 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/dont-project-to-rpitit-with-no-value.rs:4:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0046]: not all trait items implemented, missing: `foo`
-  --> $DIR/dont-project-to-rpitit-with-no-value.rs:12:1
+  --> $DIR/dont-project-to-rpitit-with-no-value.rs:11:1
    |
 LL |     fn foo(&self) -> impl Sized;
    |     ---------------------------- `foo` from trait
@@ -16,6 +7,6 @@ LL |     fn foo(&self) -> impl Sized;
 LL | impl MyTrait for i32 {
    | ^^^^^^^^^^^^^^^^^^^^ missing `foo` in implementation
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0046`.
diff --git a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.next.stderr b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.next.stderr
index b8a793e1a..d4d0124a6 100644
--- a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.next.stderr
+++ b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.next.stderr
@@ -1,14 +1,5 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/dont-project-to-rpitit-with-no-value.rs:4:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0046]: not all trait items implemented, missing: `foo`
-  --> $DIR/dont-project-to-rpitit-with-no-value.rs:12:1
+  --> $DIR/dont-project-to-rpitit-with-no-value.rs:11:1
    |
 LL |     fn foo(&self) -> impl Sized;
    |     ---------------------------- `foo` from trait
@@ -16,6 +7,6 @@ LL |     fn foo(&self) -> impl Sized;
 LL | impl MyTrait for i32 {
    | ^^^^^^^^^^^^^^^^^^^^ missing `foo` in implementation
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0046`.
diff --git a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs
index 8329ce1f8..4d50b8c92 100644
--- a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs
+++ b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs
@@ -2,7 +2,6 @@
 // revisions: current next
 
 #![feature(return_position_impl_trait_in_trait)]
-//~^ WARN the feature `return_position_impl_trait_in_trait` is incomplete
 
 trait MyTrait {
     fn foo(&self) -> impl Sized;
diff --git a/tests/ui/impl-trait/in-trait/foreign-dyn-error.rs b/tests/ui/impl-trait/in-trait/foreign-dyn-error.rs
new file mode 100644
index 000000000..ecb5e62c4
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/foreign-dyn-error.rs
@@ -0,0 +1,8 @@
+// aux-build: rpitit.rs
+
+extern crate rpitit;
+
+fn main() {
+    let _: &dyn rpitit::Foo = todo!();
+    //~^ ERROR the trait `Foo` cannot be made into an object
+}
diff --git a/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr b/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr
new file mode 100644
index 000000000..6eef392c0
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr
@@ -0,0 +1,15 @@
+error[E0038]: the trait `Foo` cannot be made into an object
+  --> $DIR/foreign-dyn-error.rs:6:12
+   |
+LL |     let _: &dyn rpitit::Foo = todo!();
+   |            ^^^^^^^^^^^^^^^^ `Foo` 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/auxiliary/rpitit.rs:8:21
+   |
+LL |     fn bar(self) -> impl Deref<Target = impl Sized>;
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait cannot be made into an object because method `bar` references an `impl Trait` type in its return type
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/impl-trait/in-trait/foreign.rs b/tests/ui/impl-trait/in-trait/foreign.rs
index f4972d948..98417b343 100644
--- a/tests/ui/impl-trait/in-trait/foreign.rs
+++ b/tests/ui/impl-trait/in-trait/foreign.rs
@@ -5,17 +5,18 @@
 
 extern crate rpitit;
 
+use rpitit::{Foo, Foreign};
 use std::sync::Arc;
 
 // Implement an RPITIT from another crate.
 struct Local;
-impl rpitit::Foo for Local {
-    fn bar() -> Arc<String> { Arc::new(String::new()) }
+impl Foo for Local {
+    fn bar(self) -> Arc<String> { Arc::new(String::new()) }
 }
 
 fn main() {
     // Witness an RPITIT from another crate.
-    let &() = <rpitit::Foreign as rpitit::Foo>::bar();
+    let &() = Foreign.bar();
 
-    let x: Arc<String> = <Local as rpitit::Foo>::bar();
+    let x: Arc<String> = Local.bar();
 }
diff --git a/tests/ui/impl-trait/in-trait/object-safety.current.stderr b/tests/ui/impl-trait/in-trait/object-safety.current.stderr
index b7f2b019a..2c340a023 100644
--- a/tests/ui/impl-trait/in-trait/object-safety.current.stderr
+++ b/tests/ui/impl-trait/in-trait/object-safety.current.stderr
@@ -42,8 +42,7 @@ LL | trait Foo {
 LL |     fn baz(&self) -> impl Debug;
    |                      ^^^^^^^^^^ ...because method `baz` references an `impl Trait` type in its return type
    = help: consider moving `baz` to another trait
-   = note: required for `Box<u32>` to implement `CoerceUnsized<Box<dyn Foo>>`
-   = note: required by cast to type `Box<dyn Foo>`
+   = note: required for the cast from `Box<u32>` to `Box<dyn Foo>`
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/ui/impl-trait/in-trait/object-safety.next.stderr b/tests/ui/impl-trait/in-trait/object-safety.next.stderr
index b7f2b019a..2c340a023 100644
--- a/tests/ui/impl-trait/in-trait/object-safety.next.stderr
+++ b/tests/ui/impl-trait/in-trait/object-safety.next.stderr
@@ -42,8 +42,7 @@ LL | trait Foo {
 LL |     fn baz(&self) -> impl Debug;
    |                      ^^^^^^^^^^ ...because method `baz` references an `impl Trait` type in its return type
    = help: consider moving `baz` to another trait
-   = note: required for `Box<u32>` to implement `CoerceUnsized<Box<dyn Foo>>`
-   = note: required by cast to type `Box<dyn Foo>`
+   = note: required for the cast from `Box<u32>` to `Box<dyn Foo>`
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/ui/impl-trait/issue-103181-1.stderr b/tests/ui/impl-trait/issue-103181-1.current.stderr
index cd026607d..e87a9d28a 100644
--- a/tests/ui/impl-trait/issue-103181-1.stderr
+++ b/tests/ui/impl-trait/issue-103181-1.current.stderr
@@ -1,5 +1,5 @@
 error[E0046]: not all trait items implemented, missing: `Error`
-  --> $DIR/issue-103181-1.rs:9:5
+  --> $DIR/issue-103181-1.rs:11:5
    |
 LL |         type Error;
    |         ---------- `Error` from trait
diff --git a/tests/ui/impl-trait/issue-103181-1.next.stderr b/tests/ui/impl-trait/issue-103181-1.next.stderr
new file mode 100644
index 000000000..e87a9d28a
--- /dev/null
+++ b/tests/ui/impl-trait/issue-103181-1.next.stderr
@@ -0,0 +1,12 @@
+error[E0046]: not all trait items implemented, missing: `Error`
+  --> $DIR/issue-103181-1.rs:11:5
+   |
+LL |         type Error;
+   |         ---------- `Error` from trait
+LL |     }
+LL |     impl HttpBody for () {
+   |     ^^^^^^^^^^^^^^^^^^^^ missing `Error` in implementation
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0046`.
diff --git a/tests/ui/impl-trait/issue-103181-1.rs b/tests/ui/impl-trait/issue-103181-1.rs
index 197aedf9d..5154abcd6 100644
--- a/tests/ui/impl-trait/issue-103181-1.rs
+++ b/tests/ui/impl-trait/issue-103181-1.rs
@@ -1,3 +1,5 @@
+// revisions: current next
+//[next] compile-flags: -Ztrait-solver=next
 // edition:2021
 
 mod hyper {
diff --git a/tests/ui/impl-trait/issue-108591.rs b/tests/ui/impl-trait/issue-108591.rs
new file mode 100644
index 000000000..6b9d14941
--- /dev/null
+++ b/tests/ui/impl-trait/issue-108591.rs
@@ -0,0 +1,30 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+struct MyTy<'a>(Vec<u8>, &'a ());
+
+impl MyTy<'_> {
+    fn one(&mut self) -> &mut impl Sized {
+        &mut self.0
+    }
+    fn two(&mut self) -> &mut (impl Sized + 'static) {
+        self.one()
+    }
+}
+
+type Opaque<'a> = impl Sized;
+fn define<'a>() -> Opaque<'a> {}
+
+fn test<'a>() {
+    None::<&'static Opaque<'a>>;
+}
+
+fn one<'a, 'b: 'b>() -> &'a impl Sized {
+    &()
+}
+fn two<'a, 'b>() {
+    one::<'a, 'b>();
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/issue-108592.rs b/tests/ui/impl-trait/issue-108592.rs
new file mode 100644
index 000000000..58a0ed9bf
--- /dev/null
+++ b/tests/ui/impl-trait/issue-108592.rs
@@ -0,0 +1,21 @@
+// check-pass
+#![feature(type_alias_impl_trait)]
+
+fn opaque<'a: 'a>() -> impl Sized {}
+fn assert_static<T: 'static>(_: T) {}
+
+fn test_closure() {
+    let closure = |_| {
+        assert_static(opaque());
+    };
+    closure(&opaque());
+}
+
+type Opaque<'a> = impl Sized;
+fn define<'a>() -> Opaque<'a> {}
+
+fn test_tait(_: &Opaque<'_>) {
+    None::<&'static Opaque<'_>>;
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/issue-36792.rs b/tests/ui/impl-trait/issue-36792.rs
new file mode 100644
index 000000000..99ae633dd
--- /dev/null
+++ b/tests/ui/impl-trait/issue-36792.rs
@@ -0,0 +1,7 @@
+// run-pass
+fn foo() -> impl Copy {
+    foo
+}
+fn main() {
+    foo();
+}
diff --git a/tests/ui/impl-trait/issues/issue-86800.rs b/tests/ui/impl-trait/issues/issue-86800.rs
index 351243c67..ec4fda322 100644
--- a/tests/ui/impl-trait/issues/issue-86800.rs
+++ b/tests/ui/impl-trait/issues/issue-86800.rs
@@ -1,14 +1,12 @@
 #![feature(type_alias_impl_trait)]
 
 // edition:2021
-// unset-rustc-env:RUST_BACKTRACE
 // compile-flags:-Z treat-err-as-bug=1
-// error-pattern:stack backtrace:
+// error-pattern: aborting due to `-Z treat-err-as-bug=1`
 // failure-status:101
-// normalize-stderr-test "note: .*" -> ""
-// normalize-stderr-test "thread 'rustc' .*" -> ""
-// normalize-stderr-test " +[0-9]+:.*\n" -> ""
-// normalize-stderr-test " +at .*\n" -> ""
+// normalize-stderr-test ".*note: .*\n\n" -> ""
+// normalize-stderr-test "thread 'rustc' panicked.*\n" -> ""
+// rustc-env:RUST_BACKTRACE=0
 
 use std::future::Future;
 
diff --git a/tests/ui/impl-trait/issues/issue-86800.stderr b/tests/ui/impl-trait/issues/issue-86800.stderr
index f3a773837..facab390d 100644
--- a/tests/ui/impl-trait/issues/issue-86800.stderr
+++ b/tests/ui/impl-trait/issues/issue-86800.stderr
@@ -1,24 +1,12 @@
 error: unconstrained opaque type
-  --> $DIR/issue-86800.rs:33:34
+  --> $DIR/issue-86800.rs:31:34
    |
 LL | type TransactionFuture<'__, O> = impl '__ + Future<Output = TransactionResult<O>>;
    |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = 
-
-
-stack backtrace:
-
 error: the compiler unexpectedly panicked. this is a bug.
 
-
-
-
-
-
-
 query stack during panic:
 #0 [type_of] computing type of `TransactionFuture::{opaque#0}`
 #1 [check_mod_item_types] checking item types in top-level module
-#2 [analysis] running analysis passes on this crate
 end of query stack
diff --git a/tests/ui/impl-trait/multiple-defining-usages-in-body.rs b/tests/ui/impl-trait/multiple-defining-usages-in-body.rs
new file mode 100644
index 000000000..c3a6f09f8
--- /dev/null
+++ b/tests/ui/impl-trait/multiple-defining-usages-in-body.rs
@@ -0,0 +1,12 @@
+trait Trait {}
+impl Trait for () {}
+
+fn foo<T: Trait, U: Trait>() -> impl Trait {
+    //~^ WARN function cannot return without recursing [unconditional_recursion]
+    let a: T = foo::<T, U>();
+    //~^ ERROR concrete type differs from previous defining opaque type use
+    loop {}
+    let _: T = foo::<U, T>();
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/multiple-defining-usages-in-body.stderr b/tests/ui/impl-trait/multiple-defining-usages-in-body.stderr
new file mode 100644
index 000000000..06991749b
--- /dev/null
+++ b/tests/ui/impl-trait/multiple-defining-usages-in-body.stderr
@@ -0,0 +1,26 @@
+warning: function cannot return without recursing
+  --> $DIR/multiple-defining-usages-in-body.rs:4:1
+   |
+LL | fn foo<T: Trait, U: Trait>() -> impl Trait {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
+LL |
+LL |     let a: T = foo::<T, U>();
+   |                ------------- recursive call site
+   |
+   = help: a `loop` may express intention better if this is on purpose
+   = note: `#[warn(unconditional_recursion)]` on by default
+
+error: concrete type differs from previous defining opaque type use
+  --> $DIR/multiple-defining-usages-in-body.rs:6:16
+   |
+LL |     let a: T = foo::<T, U>();
+   |                ^^^^^^^^^^^^^ expected `U`, got `T`
+   |
+note: previous use here
+  --> $DIR/multiple-defining-usages-in-body.rs:9:16
+   |
+LL |     let _: T = foo::<U, T>();
+   |                ^^^^^^^^^^^^^
+
+error: aborting due to previous error; 1 warning emitted
+
diff --git a/tests/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.rs b/tests/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.rs
index fa7664a83..a8a6288eb 100644
--- a/tests/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.rs
+++ b/tests/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.rs
@@ -77,7 +77,7 @@ fn hat() -> dyn std::fmt::Display { //~ ERROR return type cannot have an unboxed
 fn pug() -> dyn std::fmt::Display { //~ ERROR return type cannot have an unboxed trait object
     match 13 {
         0 => 0i32,
-        1 => 1u32, //~ ERROR `match` arms have incompatible types
+        1 => 1u32,
         _ => 2u32,
     }
 }
@@ -86,7 +86,7 @@ fn man() -> dyn std::fmt::Display { //~ ERROR return type cannot have an unboxed
     if false {
         0i32
     } else {
-        1u32 //~ ERROR `if` and `else` have incompatible types
+        1u32
     }
 }
 
diff --git a/tests/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.stderr b/tests/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.stderr
index 3c65fd998..9205d7450 100644
--- a/tests/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.stderr
+++ b/tests/ui/impl-trait/point-to-type-err-cause-on-impl-trait-return.stderr
@@ -171,39 +171,20 @@ error[E0746]: return type cannot have an unboxed trait object
 LL | fn hat() -> dyn std::fmt::Display {
    |             ^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
    |
-   = note: for information on trait objects, see <https://doc.rust-lang.org/book/ch17-02-trait-objects.html#using-trait-objects-that-allow-for-values-of-different-types>
-   = note: if all the returned values were of the same type you could use `impl std::fmt::Display` as the return type
-   = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
-   = note: you can create a new `enum` with a variant for each returned type
-help: return a boxed trait object instead
-   |
-LL | fn hat() -> Box<dyn std::fmt::Display> {
-   |             ++++                     +
-help: ... and box this value
-   |
-LL |             return Box::new(0i32);
-   |                    +++++++++    +
-help: ... and box this value
-   |
-LL |             Box::new(1u32)
-   |             +++++++++    +
-
-error[E0308]: `match` arms have incompatible types
-  --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:80:14
+help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
    |
-LL | /     match 13 {
-LL | |         0 => 0i32,
-   | |              ---- this is found to be of type `i32`
-LL | |         1 => 1u32,
-   | |              ^^^^ expected `i32`, found `u32`
-LL | |         _ => 2u32,
-LL | |     }
-   | |_____- `match` arms have incompatible types
+LL | fn hat() -> impl std::fmt::Display {
+   |             ~~~~
+help: box the return type, and wrap all of the returned values in `Box::new`
    |
-help: change the type of the numeric literal from `u32` to `i32`
+LL ~ fn hat() -> Box<dyn std::fmt::Display> {
+LL |     match 13 {
+LL |         0 => {
+LL ~             return Box::new(0i32);
+LL |         }
+LL |         _ => {
+LL ~             Box::new(1u32)
    |
-LL |         1 => 1i32,
-   |               ~~~
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:77:13
@@ -211,43 +192,18 @@ error[E0746]: return type cannot have an unboxed trait object
 LL | fn pug() -> dyn std::fmt::Display {
    |             ^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
    |
-   = note: for information on trait objects, see <https://doc.rust-lang.org/book/ch17-02-trait-objects.html#using-trait-objects-that-allow-for-values-of-different-types>
-   = note: if all the returned values were of the same type you could use `impl std::fmt::Display` as the return type
-   = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
-   = note: you can create a new `enum` with a variant for each returned type
-help: return a boxed trait object instead
-   |
-LL | fn pug() -> Box<dyn std::fmt::Display> {
-   |             ++++                     +
-help: ... and box this value
+help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
    |
-LL |         0 => Box::new(0i32),
-   |              +++++++++    +
-help: ... and box this value
-   |
-LL |         1 => Box::new(1u32),
-   |              +++++++++    +
-help: ... and box this value
-   |
-LL |         _ => Box::new(2u32),
-   |              +++++++++    +
-
-error[E0308]: `if` and `else` have incompatible types
-  --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:89:9
+LL | fn pug() -> impl std::fmt::Display {
+   |             ~~~~
+help: box the return type, and wrap all of the returned values in `Box::new`
    |
-LL | /     if false {
-LL | |         0i32
-   | |         ---- expected because of this
-LL | |     } else {
-LL | |         1u32
-   | |         ^^^^ expected `i32`, found `u32`
-LL | |     }
-   | |_____- `if` and `else` have incompatible types
-   |
-help: change the type of the numeric literal from `u32` to `i32`
+LL ~ fn pug() -> Box<dyn std::fmt::Display> {
+LL |     match 13 {
+LL ~         0 => Box::new(0i32),
+LL ~         1 => Box::new(1u32),
+LL ~         _ => Box::new(2u32),
    |
-LL |         1i32
-   |          ~~~
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:85:13
@@ -255,24 +211,20 @@ error[E0746]: return type cannot have an unboxed trait object
 LL | fn man() -> dyn std::fmt::Display {
    |             ^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
    |
-   = note: for information on trait objects, see <https://doc.rust-lang.org/book/ch17-02-trait-objects.html#using-trait-objects-that-allow-for-values-of-different-types>
-   = note: if all the returned values were of the same type you could use `impl std::fmt::Display` as the return type
-   = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
-   = note: you can create a new `enum` with a variant for each returned type
-help: return a boxed trait object instead
+help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
    |
-LL | fn man() -> Box<dyn std::fmt::Display> {
-   |             ++++                     +
-help: ... and box this value
+LL | fn man() -> impl std::fmt::Display {
+   |             ~~~~
+help: box the return type, and wrap all of the returned values in `Box::new`
    |
-LL |         Box::new(0i32)
-   |         +++++++++    +
-help: ... and box this value
+LL ~ fn man() -> Box<dyn std::fmt::Display> {
+LL |     if false {
+LL ~         Box::new(0i32)
+LL |     } else {
+LL ~         Box::new(1u32)
    |
-LL |         Box::new(1u32)
-   |         +++++++++    +
 
-error: aborting due to 14 previous errors
+error: aborting due to 12 previous errors
 
 Some errors have detailed explanations: E0308, E0746.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/impl-trait/recursive-type-alias-impl-trait-declaration-too-subtle.stderr b/tests/ui/impl-trait/recursive-type-alias-impl-trait-declaration-too-subtle.stderr
index f7aff4195..fe62a8f32 100644
--- a/tests/ui/impl-trait/recursive-type-alias-impl-trait-declaration-too-subtle.stderr
+++ b/tests/ui/impl-trait/recursive-type-alias-impl-trait-declaration-too-subtle.stderr
@@ -43,6 +43,11 @@ LL |         fn eq(&self, _other: &(Bar, i32)) -> bool {
    |
    = note: expected signature `fn(&b::Bar, &(b::Foo, i32)) -> _`
               found signature `fn(&b::Bar, &(b::Bar, i32)) -> _`
+note: this item must have the opaque type in its signature in order to be able to register hidden types
+  --> $DIR/recursive-type-alias-impl-trait-declaration-too-subtle.rs:24:9
+   |
+LL |         fn eq(&self, _other: &(Bar, i32)) -> bool {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 4 previous errors
 
diff --git a/tests/ui/impl-trait/wf-eval-order.rs b/tests/ui/impl-trait/wf-eval-order.rs
index c7d6bb870..8638fc2e7 100644
--- a/tests/ui/impl-trait/wf-eval-order.rs
+++ b/tests/ui/impl-trait/wf-eval-order.rs
@@ -31,9 +31,9 @@ fn main() {
     //
     // - `wf(typeof(x))` because we use a projection candidate.
     // - `<i32 as B>::V: Clone` because that's a bound on the trait.
-    // - `<i32 as B>::V` normalizes to `_#1` where `<i32 as A>::U == _#1`
+    // - `<i32 as B>::V` normalizes to `?1t` where `<i32 as A>::U == ?1t`
     //
-    // This all works if we evaluate `<i32 as A>::U == _#1` before
+    // This all works if we evaluate `<i32 as A>::U == ?1t` before
     // `<i32 as B>::V`, but we previously had the opposite order.
     let x = hide(X(0));
 }