Merging upstream version 1.66.0+dfsg1.

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

61 files changed, 750 insertions, 43 deletions

diff --git a/src/test/ui/impl-trait/auto-trait-leak.stderr b/src/test/ui/impl-trait/auto-trait-leak.stderr
index b6e283647..feedfc40a 100644
--- a/src/test/ui/impl-trait/auto-trait-leak.stderr
+++ b/src/test/ui/impl-trait/auto-trait-leak.stderr
@@ -9,12 +9,12 @@ note: ...which requires borrow-checking `cycle1`...
    |
 LL | fn cycle1() -> impl Clone {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires processing `cycle1`...
+note: ...which requires processing MIR for `cycle1`...
   --> $DIR/auto-trait-leak.rs:12:1
    |
 LL | fn cycle1() -> impl Clone {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires processing MIR for `cycle1`...
+note: ...which requires preparing `cycle1` for borrow checking...
   --> $DIR/auto-trait-leak.rs:12:1
    |
 LL | fn cycle1() -> impl Clone {
@@ -50,12 +50,12 @@ note: ...which requires borrow-checking `cycle2`...
    |
 LL | fn cycle2() -> impl Clone {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires processing `cycle2`...
+note: ...which requires processing MIR for `cycle2`...
   --> $DIR/auto-trait-leak.rs:19:1
    |
 LL | fn cycle2() -> impl Clone {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires processing MIR for `cycle2`...
+note: ...which requires preparing `cycle2` for borrow checking...
   --> $DIR/auto-trait-leak.rs:19:1
    |
 LL | fn cycle2() -> impl Clone {
diff --git a/src/test/ui/impl-trait/equality-rpass.stderr b/src/test/ui/impl-trait/equality-rpass.stderr
index 11eeceba0..bde8362fd 100644
--- a/src/test/ui/impl-trait/equality-rpass.stderr
+++ b/src/test/ui/impl-trait/equality-rpass.stderr
@@ -4,9 +4,9 @@ warning: the feature `specialization` is incomplete and may not be safe to use a
 LL | #![feature(specialization)]
    |            ^^^^^^^^^^^^^^
    |
-   = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
    = help: consider using `min_specialization` instead, which is more stable and complete
+   = note: `#[warn(incomplete_features)]` on by default
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/impl-trait/equality.stderr b/src/test/ui/impl-trait/equality.stderr
index d4a349551..1841b8e5d 100644
--- a/src/test/ui/impl-trait/equality.stderr
+++ b/src/test/ui/impl-trait/equality.stderr
@@ -4,9 +4,9 @@ warning: the feature `specialization` is incomplete and may not be safe to use a
 LL | #![feature(specialization)]
    |            ^^^^^^^^^^^^^^
    |
-   = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
    = help: consider using `min_specialization` instead, which is more stable and complete
+   = note: `#[warn(incomplete_features)]` on by default
 
 error[E0308]: mismatched types
   --> $DIR/equality.rs:15:5
diff --git a/src/test/ui/impl-trait/equality2.stderr b/src/test/ui/impl-trait/equality2.stderr
index 46053c6e7..e399a6102 100644
--- a/src/test/ui/impl-trait/equality2.stderr
+++ b/src/test/ui/impl-trait/equality2.stderr
@@ -4,9 +4,9 @@ warning: the feature `specialization` is incomplete and may not be safe to use a
 LL | #![feature(specialization)]
    |            ^^^^^^^^^^^^^^
    |
-   = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
    = help: consider using `min_specialization` instead, which is more stable and complete
+   = note: `#[warn(incomplete_features)]` on by default
 
 error[E0308]: mismatched types
   --> $DIR/equality2.rs:25:18
diff --git a/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.edition2015.stderr b/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.edition2015.stderr
index fd2e454e7..edf3911e2 100644
--- a/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.edition2015.stderr
+++ b/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.edition2015.stderr
@@ -1,8 +1,8 @@
-error[E0277]: the trait bound `(): AsRef<(dyn for<'r> Fn(&'r ()) + 'static)>` is not satisfied
+error[E0277]: the trait bound `(): AsRef<(dyn for<'a> Fn(&'a ()) + 'static)>` is not satisfied
   --> $DIR/generic-with-implicit-hrtb-without-dyn.rs:6:13
    |
 LL | fn ice() -> impl AsRef<Fn(&())> {
-   |             ^^^^^^^^^^^^^^^^^^^ the trait `AsRef<(dyn for<'r> Fn(&'r ()) + 'static)>` is not implemented for `()`
+   |             ^^^^^^^^^^^^^^^^^^^ the trait `AsRef<(dyn for<'a> Fn(&'a ()) + 'static)>` is not implemented for `()`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.edition2021.stderr b/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.edition2021.stderr
index 8f4092273..88e2520bf 100644
--- a/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.edition2021.stderr
+++ b/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.edition2021.stderr
@@ -9,11 +9,11 @@ help: add `dyn` keyword before this trait
 LL | fn ice() -> impl AsRef<dyn Fn(&())> {
    |                        +++
 
-error[E0277]: the trait bound `(): AsRef<(dyn for<'r> Fn(&'r ()) + 'static)>` is not satisfied
+error[E0277]: the trait bound `(): AsRef<(dyn for<'a> Fn(&'a ()) + 'static)>` is not satisfied
   --> $DIR/generic-with-implicit-hrtb-without-dyn.rs:6:13
    |
 LL | fn ice() -> impl AsRef<Fn(&())> {
-   |             ^^^^^^^^^^^^^^^^^^^ the trait `AsRef<(dyn for<'r> Fn(&'r ()) + 'static)>` is not implemented for `()`
+   |             ^^^^^^^^^^^^^^^^^^^ the trait `AsRef<(dyn for<'a> Fn(&'a ()) + 'static)>` is not implemented for `()`
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.rs b/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.rs
index 856dc7a3f..5a922697f 100644
--- a/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.rs
+++ b/src/test/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.rs
@@ -4,7 +4,7 @@
 #![allow(warnings)]
 
 fn ice() -> impl AsRef<Fn(&())> {
-    //~^ ERROR: the trait bound `(): AsRef<(dyn for<'r> Fn(&'r ()) + 'static)>` is not satisfied [E0277]
+    //~^ ERROR: the trait bound `(): AsRef<(dyn for<'a> Fn(&'a ()) + 'static)>` is not satisfied [E0277]
     //[edition2021]~| ERROR: trait objects must include the `dyn` keyword [E0782]
     todo!()
 }
diff --git a/src/test/ui/impl-trait/hidden-lifetimes.stderr b/src/test/ui/impl-trait/hidden-lifetimes.stderr
index efc228de5..3cc47e1e8 100644
--- a/src/test/ui/impl-trait/hidden-lifetimes.stderr
+++ b/src/test/ui/impl-trait/hidden-lifetimes.stderr
@@ -1,4 +1,4 @@
-error[E0700]: hidden type for `impl Swap` captures lifetime that does not appear in bounds
+error[E0700]: hidden type for `impl Swap + 'a` captures lifetime that does not appear in bounds
   --> $DIR/hidden-lifetimes.rs:29:5
    |
 LL | fn hide_ref<'a, 'b, T: 'static>(x: &'a mut &'b T) -> impl Swap + 'a {
@@ -6,12 +6,12 @@ LL | fn hide_ref<'a, 'b, T: 'static>(x: &'a mut &'b T) -> impl Swap + 'a {
 LL |     x
    |     ^
    |
-help: to declare that the `impl Trait` captures `'b`, you can add an explicit `'b` lifetime bound
+help: to declare that `impl Swap + 'a` captures `'b`, you can add an explicit `'b` lifetime bound
    |
 LL | fn hide_ref<'a, 'b, T: 'static>(x: &'a mut &'b T) -> impl Swap + 'a + 'b {
    |                                                                     ++++
 
-error[E0700]: hidden type for `impl Swap` captures lifetime that does not appear in bounds
+error[E0700]: hidden type for `impl Swap + 'a` captures lifetime that does not appear in bounds
   --> $DIR/hidden-lifetimes.rs:46:5
    |
 LL | fn hide_rc_refcell<'a, 'b: 'a, T: 'static>(x: Rc<RefCell<&'b T>>) -> impl Swap + 'a {
@@ -19,7 +19,7 @@ LL | fn hide_rc_refcell<'a, 'b: 'a, T: 'static>(x: Rc<RefCell<&'b T>>) -> impl S
 LL |     x
    |     ^
    |
-help: to declare that the `impl Trait` captures `'b`, you can add an explicit `'b` lifetime bound
+help: to declare that `impl Swap + 'a` captures `'b`, you can add an explicit `'b` lifetime bound
    |
 LL | fn hide_rc_refcell<'a, 'b: 'a, T: 'static>(x: Rc<RefCell<&'b T>>) -> impl Swap + 'a + 'b {
    |                                                                                     ++++
diff --git a/src/test/ui/impl-trait/in-trait/auxiliary/rpitit.rs b/src/test/ui/impl-trait/in-trait/auxiliary/rpitit.rs
new file mode 100644
index 000000000..74df300f8
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/auxiliary/rpitit.rs
@@ -0,0 +1,11 @@
+#![feature(return_position_impl_trait_in_trait)]
+
+pub trait Foo {
+    fn bar() -> impl Sized;
+}
+
+pub struct Foreign;
+
+impl Foo for Foreign {
+    fn bar() {}
+}
diff --git a/src/test/ui/impl-trait/in-trait/default-body-type-err-2.rs b/src/test/ui/impl-trait/in-trait/default-body-type-err-2.rs
new file mode 100644
index 000000000..45ae2b8ad
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/default-body-type-err-2.rs
@@ -0,0 +1,13 @@
+// edition:2021
+
+#![allow(incomplete_features)]
+#![feature(async_fn_in_trait)]
+
+pub trait Foo {
+    async fn woopsie_async(&self) -> String {
+        42
+        //~^ ERROR mismatched types
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/in-trait/default-body-type-err-2.stderr b/src/test/ui/impl-trait/in-trait/default-body-type-err-2.stderr
new file mode 100644
index 000000000..142b1bff1
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/default-body-type-err-2.stderr
@@ -0,0 +1,11 @@
+error[E0308]: mismatched types
+  --> $DIR/default-body-type-err-2.rs:8:9
+   |
+LL |         42
+   |         ^^- help: try using a conversion method: `.to_string()`
+   |         |
+   |         expected struct `String`, found integer
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/impl-trait/in-trait/default-body-type-err.rs b/src/test/ui/impl-trait/in-trait/default-body-type-err.rs
new file mode 100644
index 000000000..ac9baf91c
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/default-body-type-err.rs
@@ -0,0 +1,13 @@
+#![allow(incomplete_features)]
+#![feature(return_position_impl_trait_in_trait)]
+
+use std::ops::Deref;
+
+pub trait Foo {
+    fn lol(&self) -> impl Deref<Target = String> {
+        //~^ type mismatch resolving `<&i32 as Deref>::Target == String`
+        &1i32
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/in-trait/default-body-type-err.stderr b/src/test/ui/impl-trait/in-trait/default-body-type-err.stderr
new file mode 100644
index 000000000..461247a3e
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/default-body-type-err.stderr
@@ -0,0 +1,12 @@
+error[E0271]: type mismatch resolving `<&i32 as Deref>::Target == String`
+  --> $DIR/default-body-type-err.rs:7:22
+   |
+LL |     fn lol(&self) -> impl Deref<Target = String> {
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found struct `String`
+LL |
+LL |         &1i32
+   |         ----- return type was inferred to be `&i32` here
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs b/src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs
new file mode 100644
index 000000000..ad3cc7c25
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs
@@ -0,0 +1,21 @@
+// check-pass
+// edition:2021
+
+#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+use std::fmt::Debug;
+
+trait Foo {
+    async fn baz(&self) -> impl Debug {
+        ""
+    }
+}
+
+struct Bar;
+
+impl Foo for Bar {}
+
+fn main() {
+    let _ = Bar.baz();
+}
diff --git a/src/test/ui/impl-trait/in-trait/default-body.rs b/src/test/ui/impl-trait/in-trait/default-body.rs
new file mode 100644
index 000000000..b0baf5bb1
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/default-body.rs
@@ -0,0 +1,21 @@
+// check-pass
+// edition:2021
+
+#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+use std::fmt::Debug;
+
+trait Foo {
+    async fn baz(&self) -> &str {
+        ""
+    }
+}
+
+struct Bar;
+
+impl Foo for Bar {}
+
+fn main() {
+    let _ = Bar.baz();
+}
diff --git a/src/test/ui/impl-trait/in-trait/early.rs b/src/test/ui/impl-trait/in-trait/early.rs
new file mode 100644
index 000000000..9c1c2b503
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/early.rs
@@ -0,0 +1,23 @@
+// check-pass
+// edition:2021
+
+#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+pub trait Foo {
+    async fn bar<'a: 'a>(&'a mut self);
+}
+
+impl Foo for () {
+    async fn bar<'a: 'a>(&'a mut self) {}
+}
+
+pub trait Foo2 {
+    fn bar<'a: 'a>(&'a mut self) -> impl Sized + 'a;
+}
+
+impl Foo2 for () {
+    fn bar<'a: 'a>(&'a mut self) -> impl Sized + 'a {}
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/in-trait/foreign.rs b/src/test/ui/impl-trait/in-trait/foreign.rs
new file mode 100644
index 000000000..6341f5b42
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/foreign.rs
@@ -0,0 +1,9 @@
+// check-pass
+// aux-build: rpitit.rs
+
+extern crate rpitit;
+
+fn main() {
+    // Witness an RPITIT from another crate
+    let () = <rpitit::Foreign as rpitit::Foo>::bar();
+}
diff --git a/src/test/ui/impl-trait/in-trait/issue-102140.rs b/src/test/ui/impl-trait/in-trait/issue-102140.rs
new file mode 100644
index 000000000..be1e012ac
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/issue-102140.rs
@@ -0,0 +1,30 @@
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+trait Marker {}
+impl Marker for u32 {}
+
+trait MyTrait {
+    fn foo(&self) -> impl Marker
+    where
+        Self: Sized;
+}
+
+struct Outer;
+
+impl MyTrait for Outer {
+    fn foo(&self) -> impl Marker {
+        42
+    }
+}
+
+impl dyn MyTrait {
+    fn other(&self) -> impl Marker {
+        MyTrait::foo(&self)
+        //~^ ERROR the trait bound `&dyn MyTrait: MyTrait` is not satisfied
+        //~| ERROR the trait bound `&dyn MyTrait: MyTrait` is not satisfied
+        //~| ERROR the trait bound `&dyn MyTrait: MyTrait` is not satisfied
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/in-trait/issue-102140.stderr b/src/test/ui/impl-trait/in-trait/issue-102140.stderr
new file mode 100644
index 000000000..08602185f
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/issue-102140.stderr
@@ -0,0 +1,29 @@
+error[E0277]: the trait bound `&dyn MyTrait: MyTrait` is not satisfied
+  --> $DIR/issue-102140.rs:23:22
+   |
+LL |         MyTrait::foo(&self)
+   |         ------------ -^^^^
+   |         |            |
+   |         |            the trait `MyTrait` is not implemented for `&dyn MyTrait`
+   |         |            help: consider removing the leading `&`-reference
+   |         required by a bound introduced by this call
+
+error[E0277]: the trait bound `&dyn MyTrait: MyTrait` is not satisfied
+  --> $DIR/issue-102140.rs:23:9
+   |
+LL |         MyTrait::foo(&self)
+   |         ^^^^^^^^^^^^^^^^^^^ the trait `MyTrait` is not implemented for `&dyn MyTrait`
+   |
+   = help: the trait `MyTrait` is implemented for `Outer`
+
+error[E0277]: the trait bound `&dyn MyTrait: MyTrait` is not satisfied
+  --> $DIR/issue-102140.rs:23:9
+   |
+LL |         MyTrait::foo(&self)
+   |         ^^^^^^^^^^^^ the trait `MyTrait` is not implemented for `&dyn MyTrait`
+   |
+   = help: the trait `MyTrait` is implemented for `Outer`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/impl-trait/in-trait/issue-102301.rs b/src/test/ui/impl-trait/in-trait/issue-102301.rs
new file mode 100644
index 000000000..a93714a65
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/issue-102301.rs
@@ -0,0 +1,18 @@
+// check-pass
+
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+trait Foo<T> {
+    fn foo<F2: Foo<T>>(self) -> impl Foo<T>;
+}
+
+struct Bar;
+
+impl Foo<u8> for Bar {
+    fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {
+        self
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/in-trait/issue-102571.rs b/src/test/ui/impl-trait/in-trait/issue-102571.rs
new file mode 100644
index 000000000..61c91e644
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/issue-102571.rs
@@ -0,0 +1,24 @@
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+use std::fmt::Display;
+use std::ops::Deref;
+
+trait Foo {
+    fn bar(self) -> impl Deref<Target = impl Display + ?Sized>;
+}
+
+struct A;
+
+impl Foo for A {
+    fn bar(self) -> &'static str {
+        "Hello, world"
+    }
+}
+
+fn foo<T: Foo>(t: T) {
+    let () = t.bar();
+    //~^ ERROR mismatched types
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/in-trait/issue-102571.stderr b/src/test/ui/impl-trait/in-trait/issue-102571.stderr
new file mode 100644
index 000000000..87219941d
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/issue-102571.stderr
@@ -0,0 +1,14 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-102571.rs:20:9
+   |
+LL |     let () = t.bar();
+   |         ^^   ------- this expression has type `impl Deref<Target = impl std::fmt::Display + ?Sized>`
+   |         |
+   |         expected associated type, found `()`
+   |
+   = note: expected associated type `impl Deref<Target = impl std::fmt::Display + ?Sized>`
+                    found unit type `()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/impl-trait/in-trait/signature-mismatch.rs b/src/test/ui/impl-trait/in-trait/signature-mismatch.rs
new file mode 100644
index 000000000..90682631a
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/signature-mismatch.rs
@@ -0,0 +1,21 @@
+// edition:2021
+
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+use std::future::Future;
+
+pub trait AsyncTrait {
+    fn async_fn(&self, buff: &[u8]) -> impl Future<Output = Vec<u8>>;
+}
+
+pub struct Struct;
+
+impl AsyncTrait for Struct {
+    fn async_fn<'a>(&self, buff: &'a [u8]) -> impl Future<Output = Vec<u8>> + 'a {
+        //~^ ERROR `impl` item signature doesn't match `trait` item signature
+        async move { buff.to_vec() }
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/in-trait/signature-mismatch.stderr b/src/test/ui/impl-trait/in-trait/signature-mismatch.stderr
new file mode 100644
index 000000000..6663d7faa
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/signature-mismatch.stderr
@@ -0,0 +1,16 @@
+error: `impl` item signature doesn't match `trait` item signature
+  --> $DIR/signature-mismatch.rs:15:5
+   |
+LL |     fn async_fn(&self, buff: &[u8]) -> impl Future<Output = Vec<u8>>;
+   |     ----------------------------------------------------------------- expected `fn(&'1 Struct, &'2 [u8]) -> impl Future<Output = Vec<u8>> + 'static`
+...
+LL |     fn async_fn<'a>(&self, buff: &'a [u8]) -> impl Future<Output = Vec<u8>> + 'a {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 Struct, &'2 [u8]) -> impl Future<Output = Vec<u8>> + '2`
+   |
+   = note: expected `fn(&'1 Struct, &'2 [u8]) -> impl Future<Output = Vec<u8>> + 'static`
+              found `fn(&'1 Struct, &'2 [u8]) -> impl Future<Output = Vec<u8>> + '2`
+   = help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
+   = help: verify the lifetime relationships in the `trait` and `impl` between the `self` argument, the other inputs and its output
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/impl-trait/issue-100075-2.stderr b/src/test/ui/impl-trait/issue-100075-2.stderr
index 5a1f1a97d..d2dbd8c62 100644
--- a/src/test/ui/impl-trait/issue-100075-2.stderr
+++ b/src/test/ui/impl-trait/issue-100075-2.stderr
@@ -7,8 +7,8 @@ LL | fn opaque<T>(t: T) -> impl Sized {
 LL |     opaque(Some(t))
    |     --------------- recursive call site
    |
-   = note: `#[warn(unconditional_recursion)]` on by default
    = help: a `loop` may express intention better if this is on purpose
+   = note: `#[warn(unconditional_recursion)]` on by default
 
 error[E0720]: cannot resolve opaque type
   --> $DIR/issue-100075-2.rs:1:23
diff --git a/src/test/ui/impl-trait/issue-102605.rs b/src/test/ui/impl-trait/issue-102605.rs
new file mode 100644
index 000000000..3bbdf35af
--- /dev/null
+++ b/src/test/ui/impl-trait/issue-102605.rs
@@ -0,0 +1,15 @@
+// edition:2021
+
+async fn foo() -> Result<(), String> {
+    Ok(())
+}
+
+fn convert_result<T, E>(r: Result<T, E>) -> Option<T> {
+    None
+}
+
+fn main() -> Option<()> {
+    //~^ ERROR `main` has invalid return type `Option<()>`
+    convert_result(foo())
+    //~^ ERROR mismatched types
+}
diff --git a/src/test/ui/impl-trait/issue-102605.stderr b/src/test/ui/impl-trait/issue-102605.stderr
new file mode 100644
index 000000000..d4aba9149
--- /dev/null
+++ b/src/test/ui/impl-trait/issue-102605.stderr
@@ -0,0 +1,41 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-102605.rs:13:20
+   |
+LL |     convert_result(foo())
+   |     -------------- ^^^^^ expected enum `Result`, found opaque type
+   |     |
+   |     arguments to this function are incorrect
+   |
+note: while checking the return type of the `async fn`
+  --> $DIR/issue-102605.rs:3:19
+   |
+LL | async fn foo() -> Result<(), String> {
+   |                   ^^^^^^^^^^^^^^^^^^ checked the `Output` of this `async fn`, found opaque type
+   = note:     expected enum `Result<(), _>`
+           found opaque type `impl Future<Output = Result<(), String>>`
+note: function defined here
+  --> $DIR/issue-102605.rs:7:4
+   |
+LL | fn convert_result<T, E>(r: Result<T, E>) -> Option<T> {
+   |    ^^^^^^^^^^^^^^       ---------------
+help: consider `await`ing on the `Future`
+   |
+LL |     convert_result(foo().await)
+   |                         ++++++
+help: try wrapping the expression in `Err`
+   |
+LL |     convert_result(Err(foo()))
+   |                    ++++     +
+
+error[E0277]: `main` has invalid return type `Option<()>`
+  --> $DIR/issue-102605.rs:11:14
+   |
+LL | fn main() -> Option<()> {
+   |              ^^^^^^^^^^ `main` can only return types that implement `Termination`
+   |
+   = help: consider using `()`, or a `Result`
+
+error: aborting due to 2 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/impl-trait/issue-103181-1.rs b/src/test/ui/impl-trait/issue-103181-1.rs
new file mode 100644
index 000000000..197aedf9d
--- /dev/null
+++ b/src/test/ui/impl-trait/issue-103181-1.rs
@@ -0,0 +1,85 @@
+// edition:2021
+
+mod hyper {
+    use std::{fmt::Debug, future::Future, marker::PhantomData, pin::Pin, task::Poll};
+
+    pub trait HttpBody {
+        type Error;
+    }
+    impl HttpBody for () {
+        //~^ ERROR not all trait items implemented, missing: `Error`
+        // don't implement `Error` here for the ICE
+    }
+
+    pub struct Server<I, S>(I, S);
+
+    pub fn serve<I, S>(_: S) -> Server<I, S> {
+        todo!()
+    }
+
+    impl<S, B> Future for Server<(), S>
+    where
+        S: MakeServiceRef<(), (), ResBody = B>,
+        B: HttpBody,
+        B::Error: Debug,
+    {
+        type Output = ();
+
+        fn poll(self: Pin<&mut Self>, _: &mut std::task::Context<'_>) -> Poll<Self::Output> {
+            todo!()
+        }
+    }
+
+    pub trait MakeServiceRef<Target, ReqBody> {
+        type ResBody;
+    }
+
+    impl<T, S> MakeServiceRef<(), ()> for T
+    where
+        T: for<'a> Service<&'a (), Response = S>,
+        S: Service<()>,
+    {
+        type ResBody = ();
+    }
+
+    pub struct MakeServiceFn<F>(pub F);
+    pub struct ServiceFn<F, R>(pub PhantomData<(F, R)>);
+
+    pub trait Service<Request> {
+        type Response;
+    }
+
+    impl<'t, F, Ret, Target, Svc> Service<&'t Target> for MakeServiceFn<F>
+    where
+        F: Fn() -> Ret,
+        Ret: Future<Output = Result<Svc, ()>>,
+    {
+        type Response = Svc;
+    }
+
+    impl<F, ReqBody, Ret, ResBody, E> Service<ReqBody> for ServiceFn<F, ReqBody>
+    where
+        F: Fn() -> Ret,
+        Ret: Future<Output = Result<ResBody, E>>,
+    {
+        type Response = ResBody;
+    }
+}
+
+async fn smarvice() -> Result<(), ()> {
+    Ok(())
+}
+
+fn service_fn<F, R, S>(f: F) -> hyper::ServiceFn<F, R>
+where
+    F: Fn() -> S,
+{
+    hyper::ServiceFn(std::marker::PhantomData)
+}
+
+async fn iceice() {
+    let service = hyper::MakeServiceFn(|| async { Ok::<_, ()>(service_fn(|| smarvice())) });
+    hyper::serve::<(), _>(service).await;
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/issue-103181-1.stderr b/src/test/ui/impl-trait/issue-103181-1.stderr
new file mode 100644
index 000000000..cd026607d
--- /dev/null
+++ b/src/test/ui/impl-trait/issue-103181-1.stderr
@@ -0,0 +1,12 @@
+error[E0046]: not all trait items implemented, missing: `Error`
+  --> $DIR/issue-103181-1.rs:9:5
+   |
+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/src/test/ui/impl-trait/issue-103181-2.rs b/src/test/ui/impl-trait/issue-103181-2.rs
new file mode 100644
index 000000000..b43ac4507
--- /dev/null
+++ b/src/test/ui/impl-trait/issue-103181-2.rs
@@ -0,0 +1,29 @@
+// edition:2021
+
+trait SendFuture: Send {
+    type Output;
+}
+
+impl<Fut: Send> SendFuture for Fut {
+    type Output = ();
+}
+
+async fn broken_fut() {
+    ident_error;
+    //~^ ERROR cannot find value `ident_error` in this scope
+}
+
+// triggers normalization of `<Fut as SendFuture>::Output`,
+// which requires `Fut: Send`.
+fn normalize<Fut: SendFuture>(_: Fut, _: Fut::Output) {}
+
+async fn iceice<A, B>()
+// <- async fn is necessary
+where
+    A: Send,
+    B: Send, // <- a second bound
+{
+    normalize(broken_fut(), ());
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/issue-103181-2.stderr b/src/test/ui/impl-trait/issue-103181-2.stderr
new file mode 100644
index 000000000..5eb2dd918
--- /dev/null
+++ b/src/test/ui/impl-trait/issue-103181-2.stderr
@@ -0,0 +1,9 @@
+error[E0425]: cannot find value `ident_error` in this scope
+  --> $DIR/issue-103181-2.rs:12:5
+   |
+LL |     ident_error;
+   |     ^^^^^^^^^^^ not found in this scope
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0425`.
diff --git a/src/test/ui/impl-trait/issue-103599.stderr b/src/test/ui/impl-trait/issue-103599.stderr
index 79fb355dd..82038c1dc 100644
--- a/src/test/ui/impl-trait/issue-103599.stderr
+++ b/src/test/ui/impl-trait/issue-103599.stderr
@@ -7,8 +7,8 @@ LL |
 LL |     wrap(wrap(x))
    |          ------- recursive call site
    |
-   = note: `#[warn(unconditional_recursion)]` on by default
    = help: a `loop` may express intention better if this is on purpose
+   = note: `#[warn(unconditional_recursion)]` on by default
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/impl-trait/issue-86465.rs b/src/test/ui/impl-trait/issue-86465.rs
index a79bb6474..8c7b41d73 100644
--- a/src/test/ui/impl-trait/issue-86465.rs
+++ b/src/test/ui/impl-trait/issue-86465.rs
@@ -1,6 +1,10 @@
 #![feature(type_alias_impl_trait)]
 
-type X<'a, 'b> = impl std::fmt::Debug;
+pub trait Captures<'a> {}
+
+impl<'a, T: ?Sized> Captures<'a> for T {}
+
+type X<'a, 'b> = impl std::fmt::Debug + Captures<'a> + Captures<'b>;
 
 fn f<'t, 'u>(a: &'t u32, b: &'u u32) -> (X<'t, 'u>, X<'u, 't>) {
     (a, a)
diff --git a/src/test/ui/impl-trait/issue-86465.stderr b/src/test/ui/impl-trait/issue-86465.stderr
index 90d6904ed..b949b2b42 100644
--- a/src/test/ui/impl-trait/issue-86465.stderr
+++ b/src/test/ui/impl-trait/issue-86465.stderr
@@ -1,5 +1,5 @@
 error: concrete type differs from previous defining opaque type use
-  --> $DIR/issue-86465.rs:6:5
+  --> $DIR/issue-86465.rs:10:5
    |
 LL |     (a, a)
    |     ^^^^^^
diff --git a/src/test/ui/impl-trait/issue-87450.stderr b/src/test/ui/impl-trait/issue-87450.stderr
index 5019e544b..173fca63f 100644
--- a/src/test/ui/impl-trait/issue-87450.stderr
+++ b/src/test/ui/impl-trait/issue-87450.stderr
@@ -7,8 +7,8 @@ LL | fn foo() -> impl Fn() {
 LL |     wrap(wrap(wrap(wrap(wrap(wrap(wrap(foo())))))))
    |                                        ----- recursive call site
    |
-   = note: `#[warn(unconditional_recursion)]` on by default
    = help: a `loop` may express intention better if this is on purpose
+   = note: `#[warn(unconditional_recursion)]` on by default
 
 error[E0720]: cannot resolve opaque type
   --> $DIR/issue-87450.rs:5:13
diff --git a/src/test/ui/impl-trait/issues/issue-78722.rs b/src/test/ui/impl-trait/issues/issue-78722.rs
index 90d1cd379..9ee1ba3d3 100644
--- a/src/test/ui/impl-trait/issues/issue-78722.rs
+++ b/src/test/ui/impl-trait/issues/issue-78722.rs
@@ -12,7 +12,7 @@ struct Bug {
         }
         let f: F = async { 1 };
         //~^ ERROR `async` blocks are not allowed in constants
-        //~| ERROR destructors cannot be evaluated at compile-time
+        //~| ERROR destructor of
         1
     }],
 }
diff --git a/src/test/ui/impl-trait/issues/issue-78722.stderr b/src/test/ui/impl-trait/issues/issue-78722.stderr
index 9a0ffbc89..a96994f5a 100644
--- a/src/test/ui/impl-trait/issues/issue-78722.stderr
+++ b/src/test/ui/impl-trait/issues/issue-78722.stderr
@@ -7,11 +7,11 @@ LL |         let f: F = async { 1 };
    = note: see issue #85368 <https://github.com/rust-lang/rust/issues/85368> for more information
    = help: add `#![feature(const_async_blocks)]` to the crate attributes to enable
 
-error[E0493]: destructors cannot be evaluated at compile-time
+error[E0493]: destructor of `F` cannot be evaluated at compile-time
   --> $DIR/issue-78722.rs:13:13
    |
 LL |         let f: F = async { 1 };
-   |             ^ constants cannot evaluate destructors
+   |             ^ the destructor for this type cannot be evaluated in constants
 ...
 LL |     }],
    |     - value is dropped here
diff --git a/src/test/ui/impl-trait/issues/issue-86800.stderr b/src/test/ui/impl-trait/issues/issue-86800.stderr
index 135d06d44..6c4aa3567 100644
--- a/src/test/ui/impl-trait/issues/issue-86800.stderr
+++ b/src/test/ui/impl-trait/issues/issue-86800.stderr
@@ -1,3 +1,11 @@
+error: unconstrained opaque type
+  --> $DIR/issue-86800.rs:33:34
+   |
+LL | type TransactionFuture<'__, O> = impl '__ + Future<Output = TransactionResult<O>>;
+   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = 
+
 
 stack backtrace:
 
@@ -12,8 +20,7 @@ error: internal compiler error: unexpected panic
 
 
 query stack during panic:
-#0 [mir_borrowck] borrow-checking `execute_transaction_fut`
-#1 [type_of] computing type of `TransactionFuture::{opaque#0}`
-#2 [check_mod_item_types] checking item types in top-level module
-#3 [analysis] running analysis passes on this crate
+#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/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unrelated.stderr b/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unrelated.stderr
index cb1dc0b7d..ec49a6179 100644
--- a/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unrelated.stderr
+++ b/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unrelated.stderr
@@ -7,7 +7,7 @@ LL | fn upper_bounds<'a, 'b, 'c, 'd, 'e>(a: Ordinary<'a>, b: Ordinary<'b>) -> im
 LL |     if condition() { a } else { b }
    |                                 ^
    |
-help: to declare that the `impl Trait` captures `'b`, you can add an explicit `'b` lifetime bound
+help: to declare that `impl Trait<'d, 'e>` captures `'b`, you can add an explicit `'b` lifetime bound
    |
 LL | fn upper_bounds<'a, 'b, 'c, 'd, 'e>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'d, 'e> + 'b
    |                                                                                             ++++
diff --git a/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unsuited.stderr b/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unsuited.stderr
index 4388e6601..c36f9bc69 100644
--- a/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unsuited.stderr
+++ b/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unsuited.stderr
@@ -7,7 +7,7 @@ LL | fn upper_bounds<'a, 'b>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'a,
 LL |     if condition() { a } else { b }
    |                                 ^
    |
-help: to declare that the `impl Trait` captures `'b`, you can add an explicit `'b` lifetime bound
+help: to declare that `impl Trait<'a, 'b>` captures `'b`, you can add an explicit `'b` lifetime bound
    |
 LL | fn upper_bounds<'a, 'b>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'a, 'b> + 'b
    |                                                                                 ++++
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index 16767abd7..9c81791fb 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -6,7 +6,7 @@ LL | fn elided(x: &i32) -> impl Copy { x }
    |              |
    |              hidden type `&i32` captures the anonymous lifetime defined here
    |
-help: to declare that the `impl Trait` captures `'_`, you can add an explicit `'_` lifetime bound
+help: to declare that `impl Copy` captures `'_`, you can add an explicit `'_` lifetime bound
    |
 LL | fn elided(x: &i32) -> impl Copy + '_ { x }
    |                                 ++++
@@ -19,7 +19,7 @@ LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
    |             |
    |             hidden type `&'a i32` captures the lifetime `'a` as defined here
    |
-help: to declare that the `impl Trait` captures `'a`, you can add an explicit `'a` lifetime bound
+help: to declare that `impl Copy` captures `'a`, you can add an explicit `'a` lifetime bound
    |
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                          ++++
@@ -32,7 +32,7 @@ LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
    |               |
    |               let's call the lifetime of this reference `'1`
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound to the lifetime of argument `x`
+help: consider changing `impl Copy + 'static`'s explicit `'static` bound to the lifetime of argument `x`
    |
 LL | fn elided2(x: &i32) -> impl Copy + '_ { x }
    |                                    ~~
@@ -47,7 +47,7 @@ error: lifetime may not live long enough
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
    |              -- lifetime `'a` defined here            ^ returning this value requires that `'a` must outlive `'static`
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound to the lifetime of argument `x`
+help: consider changing `impl Copy + 'static`'s explicit `'static` bound to the lifetime of argument `x`
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                             ~~
@@ -76,7 +76,7 @@ help: to declare that the trait object captures data from argument `x`, you can
    |
 LL | fn elided5(x: &i32) -> (Box<dyn Debug + '_>, impl Debug) { (Box::new(x), x) }
    |                                       ++++
-help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'_` lifetime bound
+help: to declare that `impl Debug` captures data from argument `x`, you can add an explicit `'_` lifetime bound
    |
 LL | fn elided5(x: &i32) -> (Box<dyn Debug>, impl Debug + '_) { (Box::new(x), x) }
    |                                                    ++++
@@ -87,7 +87,7 @@ error: lifetime may not live long enough
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    |               -- lifetime `'a` defined here                         ^ returning this value requires that `'a` must outlive `'static`
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound to the lifetime of argument `x`
+help: consider changing `impl LifetimeTrait<'a> + 'static`'s explicit `'static` bound to the lifetime of argument `x`
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'a { x }
    |                                                           ~~
@@ -104,7 +104,7 @@ LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32
 LL |     move |_| println!("{}", y)
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: to declare that the `impl Trait` captures `'b`, you can add an explicit `'b` lifetime bound
+help: to declare that `impl Fn(&'a u32)` captures `'b`, you can add an explicit `'b` lifetime bound
    |
 LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32) + 'b {
    |                                                                              ++++
diff --git a/src/test/ui/impl-trait/nested-return-type2-tait.rs b/src/test/ui/impl-trait/nested-return-type2-tait.rs
index 42613d5cc..089018a1c 100644
--- a/src/test/ui/impl-trait/nested-return-type2-tait.rs
+++ b/src/test/ui/impl-trait/nested-return-type2-tait.rs
@@ -26,6 +26,7 @@ type Sendable = impl Send;
 // var to make it uphold the `: Duh` bound on `Trait::Assoc`. The opaque
 // type does not implement `Duh`, but if its hidden type does.
 fn foo() -> impl Trait<Assoc = Sendable> {
+    //~^ WARN opaque type `impl Trait<Assoc = Sendable>` does not satisfy its associated type bounds
     || 42
 }
 
diff --git a/src/test/ui/impl-trait/nested-return-type2-tait.stderr b/src/test/ui/impl-trait/nested-return-type2-tait.stderr
new file mode 100644
index 000000000..a8eb69cfc
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type2-tait.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `impl Trait<Assoc = Sendable>` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type2-tait.rs:28:24
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `Sendable`
+...
+LL | fn foo() -> impl Trait<Assoc = Sendable> {
+   |                        ^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | type Sendable = impl Send + Duh;
+   |                           +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/nested-return-type2.rs b/src/test/ui/impl-trait/nested-return-type2.rs
index 39928d543..cc1f1f4ec 100644
--- a/src/test/ui/impl-trait/nested-return-type2.rs
+++ b/src/test/ui/impl-trait/nested-return-type2.rs
@@ -23,6 +23,7 @@ impl<R: Duh, F: FnMut() -> R> Trait for F {
 // Lazy TAIT would error out, but we inserted a hack to make it work again,
 // keeping backwards compatibility.
 fn foo() -> impl Trait<Assoc = impl Send> {
+    //~^ WARN opaque type `impl Trait<Assoc = impl Send>` does not satisfy its associated type bounds
     || 42
 }
 
diff --git a/src/test/ui/impl-trait/nested-return-type2.stderr b/src/test/ui/impl-trait/nested-return-type2.stderr
new file mode 100644
index 000000000..3aed05ca1
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type2.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `impl Trait<Assoc = impl Send>` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type2.rs:25:24
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `impl Send`
+...
+LL | fn foo() -> impl Trait<Assoc = impl Send> {
+   |                        ^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | fn foo() -> impl Trait<Assoc = impl Send + Duh> {
+   |                                          +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait.rs b/src/test/ui/impl-trait/nested-return-type3-tait.rs
index 3936f4dbb..3a97e35b4 100644
--- a/src/test/ui/impl-trait/nested-return-type3-tait.rs
+++ b/src/test/ui/impl-trait/nested-return-type3-tait.rs
@@ -17,6 +17,7 @@ impl<F: Duh> Trait for F {
 type Sendable = impl Send;
 
 fn foo() -> impl Trait<Assoc = Sendable> {
+    //~^ WARN opaque type `impl Trait<Assoc = Sendable>` does not satisfy its associated type bounds
     42
 }
 
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait.stderr b/src/test/ui/impl-trait/nested-return-type3-tait.stderr
new file mode 100644
index 000000000..5f58c8dca
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type3-tait.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `impl Trait<Assoc = Sendable>` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type3-tait.rs:19:24
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `Sendable`
+...
+LL | fn foo() -> impl Trait<Assoc = Sendable> {
+   |                        ^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | type Sendable = impl Send + Duh;
+   |                           +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait2.rs b/src/test/ui/impl-trait/nested-return-type3-tait2.rs
index 56778ed90..5b6f78a98 100644
--- a/src/test/ui/impl-trait/nested-return-type3-tait2.rs
+++ b/src/test/ui/impl-trait/nested-return-type3-tait2.rs
@@ -16,6 +16,7 @@ impl<F: Duh> Trait for F {
 
 type Sendable = impl Send;
 type Traitable = impl Trait<Assoc = Sendable>;
+//~^ WARN opaque type `Traitable` does not satisfy its associated type bounds
 
 fn foo() -> Traitable {
     42
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait2.stderr b/src/test/ui/impl-trait/nested-return-type3-tait2.stderr
new file mode 100644
index 000000000..c07f6ead7
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type3-tait2.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `Traitable` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type3-tait2.rs:18:29
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `Sendable`
+...
+LL | type Traitable = impl Trait<Assoc = Sendable>;
+   |                             ^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | type Sendable = impl Send + Duh;
+   |                           +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait3.rs b/src/test/ui/impl-trait/nested-return-type3-tait3.rs
index 04c6c92b1..394d8f581 100644
--- a/src/test/ui/impl-trait/nested-return-type3-tait3.rs
+++ b/src/test/ui/impl-trait/nested-return-type3-tait3.rs
@@ -15,6 +15,7 @@ impl<F: Duh> Trait for F {
 }
 
 type Traitable = impl Trait<Assoc = impl Send>;
+//~^ WARN opaque type `Traitable` does not satisfy its associated type bounds
 
 fn foo() -> Traitable {
     42
diff --git a/src/test/ui/impl-trait/nested-return-type3-tait3.stderr b/src/test/ui/impl-trait/nested-return-type3-tait3.stderr
new file mode 100644
index 000000000..d98ad8922
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type3-tait3.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `Traitable` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type3-tait3.rs:17:29
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `impl Send`
+...
+LL | type Traitable = impl Trait<Assoc = impl Send>;
+   |                             ^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | type Traitable = impl Trait<Assoc = impl Send + Duh>;
+   |                                               +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/nested-return-type3.rs b/src/test/ui/impl-trait/nested-return-type3.rs
index 74b4dae22..5a764fc4c 100644
--- a/src/test/ui/impl-trait/nested-return-type3.rs
+++ b/src/test/ui/impl-trait/nested-return-type3.rs
@@ -13,6 +13,7 @@ impl<F: Duh> Trait for F {
 }
 
 fn foo() -> impl Trait<Assoc = impl Send> {
+    //~^ WARN opaque type `impl Trait<Assoc = impl Send>` does not satisfy its associated type bounds
     42
 }
 
diff --git a/src/test/ui/impl-trait/nested-return-type3.stderr b/src/test/ui/impl-trait/nested-return-type3.stderr
new file mode 100644
index 000000000..632de71aa
--- /dev/null
+++ b/src/test/ui/impl-trait/nested-return-type3.stderr
@@ -0,0 +1,17 @@
+warning: opaque type `impl Trait<Assoc = impl Send>` does not satisfy its associated type bounds
+  --> $DIR/nested-return-type3.rs:15:24
+   |
+LL |     type Assoc: Duh;
+   |                 --- this associated type bound is unsatisfied for `impl Send`
+...
+LL | fn foo() -> impl Trait<Assoc = impl Send> {
+   |                        ^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(opaque_hidden_inferred_bound)]` on by default
+help: add this bound
+   |
+LL | fn foo() -> impl Trait<Assoc = impl Send + Duh> {
+   |                                          +++++
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/impl-trait/normalize-tait-in-const.rs b/src/test/ui/impl-trait/normalize-tait-in-const.rs
new file mode 100644
index 000000000..020bcbb83
--- /dev/null
+++ b/src/test/ui/impl-trait/normalize-tait-in-const.rs
@@ -0,0 +1,39 @@
+// known-bug: #103507
+// failure-status: 101
+// normalize-stderr-test "note: .*\n\n" -> ""
+// normalize-stderr-test "thread 'rustc' panicked.*\n" -> ""
+// rustc-env:RUST_BACKTRACE=0
+
+#![feature(type_alias_impl_trait)]
+#![feature(const_trait_impl)]
+#![feature(const_refs_to_cell)]
+#![feature(inline_const)]
+
+use std::marker::Destruct;
+
+trait T {
+    type Item;
+}
+
+type Alias<'a> = impl T<Item = &'a ()>;
+
+struct S;
+impl<'a> T for &'a S {
+    type Item = &'a ();
+}
+
+const fn filter_positive<'a>() -> &'a Alias<'a> {
+    &&S
+}
+
+const fn with_positive<F: ~const for<'a> Fn(&'a Alias<'a>) + ~const Destruct>(fun: F) {
+    fun(filter_positive());
+}
+
+const fn foo(_: &Alias<'_>) {}
+
+const BAR: () = {
+    with_positive(foo);
+};
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/normalize-tait-in-const.stderr b/src/test/ui/impl-trait/normalize-tait-in-const.stderr
new file mode 100644
index 000000000..b9fc8726f
--- /dev/null
+++ b/src/test/ui/impl-trait/normalize-tait-in-const.stderr
@@ -0,0 +1,8 @@
+error: internal compiler error: compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:198:90: Failed to normalize <for<'a, 'b> fn(&'a Alias<'b>) {foo} as std::ops::FnOnce<(&&S,)>>::Output, maybe try to call `try_normalize_erasing_regions` instead
+
+query stack during panic:
+#0 [eval_to_allocation_raw] const-evaluating + checking `BAR`
+#1 [eval_to_const_value_raw] simplifying constant for the type system `BAR`
+end of query stack
+error: aborting due to previous error
+
diff --git a/src/test/ui/impl-trait/region-escape-via-bound.stderr b/src/test/ui/impl-trait/region-escape-via-bound.stderr
index fdb2fe022..44a790cb1 100644
--- a/src/test/ui/impl-trait/region-escape-via-bound.stderr
+++ b/src/test/ui/impl-trait/region-escape-via-bound.stderr
@@ -7,7 +7,7 @@ LL | fn foo<'x, 'y>(x: Cell<&'x u32>) -> impl Trait<'y>
 LL |     x
    |     ^
    |
-help: to declare that the `impl Trait` captures `'x`, you can add an explicit `'x` lifetime bound
+help: to declare that `impl Trait<'y>` captures `'x`, you can add an explicit `'x` lifetime bound
    |
 LL | fn foo<'x, 'y>(x: Cell<&'x u32>) -> impl Trait<'y> + 'x
    |                                                    ++++
diff --git a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
index b86815231..b365bd884 100644
--- a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
+++ b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
@@ -6,7 +6,7 @@ LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
 LL |         self.x.iter().map(|a| a.0)
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: to declare that the `impl Trait` captures `'_`, you can add an explicit `'_` lifetime bound
+help: to declare that `impl Iterator<Item = u32>` captures `'_`, you can add an explicit `'_` lifetime bound
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
    |                                                           ++++
@@ -19,7 +19,7 @@ LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
 LL |         self.x.iter().map(|a| a.0)
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: to declare that the `impl Trait` captures `'_`, you can add an explicit `'_` lifetime bound
+help: to declare that `impl Iterator<Item = u32>` captures `'_`, you can add an explicit `'_` lifetime bound
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
    |                                                           ++++
@@ -32,7 +32,7 @@ LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
 LL |         self.x.iter().map(|a| a.0)
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: to declare that the `impl Trait` captures `'a`, you can add an explicit `'a` lifetime bound
+help: to declare that `impl Iterator<Item = u32>` captures `'a`, you can add an explicit `'a` lifetime bound
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
    |                                                             ++++
@@ -45,7 +45,7 @@ LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
 LL |         self.x.iter().map(|a| a.0)
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: to declare that the `impl Trait` captures `'a`, you can add an explicit `'a` lifetime bound
+help: to declare that `impl Iterator<Item = u32>` captures `'a`, you can add an explicit `'a` lifetime bound
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
    |                                                             ++++
diff --git a/src/test/ui/impl-trait/unactionable_diagnostic.fixed b/src/test/ui/impl-trait/unactionable_diagnostic.fixed
new file mode 100644
index 000000000..6c2505177
--- /dev/null
+++ b/src/test/ui/impl-trait/unactionable_diagnostic.fixed
@@ -0,0 +1,25 @@
+// run-rustfix
+
+pub trait Trait {}
+
+pub struct Foo;
+
+impl Trait for Foo {}
+
+fn foo<'x, P>(
+    _post: P,
+    x: &'x Foo,
+) -> &'x impl Trait {
+    x
+}
+
+pub fn bar<'t, T: 't>(
+    //~^ HELP: consider adding an explicit lifetime bound...
+    post: T,
+    x: &'t Foo,
+) -> &'t impl Trait {
+    foo(post, x)
+    //~^ ERROR: the parameter type `T` may not live long enough
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/unactionable_diagnostic.rs b/src/test/ui/impl-trait/unactionable_diagnostic.rs
new file mode 100644
index 000000000..bce35cbdd
--- /dev/null
+++ b/src/test/ui/impl-trait/unactionable_diagnostic.rs
@@ -0,0 +1,25 @@
+// run-rustfix
+
+pub trait Trait {}
+
+pub struct Foo;
+
+impl Trait for Foo {}
+
+fn foo<'x, P>(
+    _post: P,
+    x: &'x Foo,
+) -> &'x impl Trait {
+    x
+}
+
+pub fn bar<'t, T>(
+    //~^ HELP: consider adding an explicit lifetime bound...
+    post: T,
+    x: &'t Foo,
+) -> &'t impl Trait {
+    foo(post, x)
+    //~^ ERROR: the parameter type `T` may not live long enough
+}
+
+fn main() {}
diff --git a/src/test/ui/impl-trait/unactionable_diagnostic.stderr b/src/test/ui/impl-trait/unactionable_diagnostic.stderr
new file mode 100644
index 000000000..a32004cda
--- /dev/null
+++ b/src/test/ui/impl-trait/unactionable_diagnostic.stderr
@@ -0,0 +1,14 @@
+error[E0309]: the parameter type `T` may not live long enough
+  --> $DIR/unactionable_diagnostic.rs:21:5
+   |
+LL |     foo(post, x)
+   |     ^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound...
+   |
+LL | pub fn bar<'t, T: 't>(
+   |                 ++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0309`.
diff --git a/src/test/ui/impl-trait/where-allowed.stderr b/src/test/ui/impl-trait/where-allowed.stderr
index 9b346387d..2e7c7ca40 100644
--- a/src/test/ui/impl-trait/where-allowed.stderr
+++ b/src/test/ui/impl-trait/where-allowed.stderr
@@ -301,9 +301,9 @@ error: defaults for type parameters are only allowed in `struct`, `enum`, `type`
 LL | impl <T = impl Debug> T {}
    |       ^^^^^^^^^^^^^^
    |
-   = note: `#[deny(invalid_type_param_default)]` 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 #36887 <https://github.com/rust-lang/rust/issues/36887>
+   = note: `#[deny(invalid_type_param_default)]` on by default
 
 error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
   --> $DIR/where-allowed.rs:241:36