Merging upstream version 1.75.0+dfsg1.

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

87 files changed, 230 insertions, 142 deletions

diff --git a/tests/ui/impl-trait/in-trait/anonymize-binders-for-refine.rs b/tests/ui/impl-trait/in-trait/anonymize-binders-for-refine.rs
index e62662f2f..09fbef2ec 100644
--- a/tests/ui/impl-trait/in-trait/anonymize-binders-for-refine.rs
+++ b/tests/ui/impl-trait/in-trait/anonymize-binders-for-refine.rs
@@ -1,7 +1,6 @@
 // compile-flags: --crate-type=lib
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait)]
 #![deny(refining_impl_trait)]
 
 pub trait Tr<T> {
diff --git a/tests/ui/impl-trait/in-trait/assumed-wf-bounds-in-impl.rs b/tests/ui/impl-trait/in-trait/assumed-wf-bounds-in-impl.rs
index 2a61c5cc8..afb9992de 100644
--- a/tests/ui/impl-trait/in-trait/assumed-wf-bounds-in-impl.rs
+++ b/tests/ui/impl-trait/in-trait/assumed-wf-bounds-in-impl.rs
@@ -2,13 +2,13 @@
 // edition: 2021
 // issue: 113796
 
-#![feature(async_fn_in_trait)]
 
 trait AsyncLendingIterator {
     type Item<'a>
     where
         Self: 'a;
 
+    #[allow(async_fn_in_trait)]
     async fn next(&mut self) -> Option<Self::Item<'_>>;
 }
 
diff --git a/tests/ui/impl-trait/in-trait/async-and-ret-ref.rs b/tests/ui/impl-trait/in-trait/async-and-ret-ref.rs
new file mode 100644
index 000000000..af6ffe833
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/async-and-ret-ref.rs
@@ -0,0 +1,11 @@
+// edition:2021
+// https://github.com/rust-lang/rust/issues/117547
+
+trait T {}
+
+trait MyTrait {
+    async fn foo() -> &'static impl T;
+    //~^ ERROR the associated type `<Self as MyTrait>::{opaque#0}` may not live long enough
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/in-trait/async-and-ret-ref.stderr b/tests/ui/impl-trait/in-trait/async-and-ret-ref.stderr
new file mode 100644
index 000000000..7c9028a8c
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/async-and-ret-ref.stderr
@@ -0,0 +1,14 @@
+error[E0310]: the associated type `<Self as MyTrait>::{opaque#0}` may not live long enough
+  --> $DIR/async-and-ret-ref.rs:7:5
+   |
+LL |     async fn foo() -> &'static impl T;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     |
+   |     the associated type `<Self as MyTrait>::{opaque#0}` must be valid for the static lifetime...
+   |     ...so that the reference type `&'static impl T` does not outlive the data it points at
+   |
+   = help: consider adding an explicit lifetime bound `<Self as MyTrait>::{opaque#0}: 'static`...
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0310`.
diff --git a/tests/ui/impl-trait/in-trait/auxiliary/rpitit.rs b/tests/ui/impl-trait/in-trait/auxiliary/rpitit.rs
index 6e9940211..a213994ff 100644
--- a/tests/ui/impl-trait/in-trait/auxiliary/rpitit.rs
+++ b/tests/ui/impl-trait/in-trait/auxiliary/rpitit.rs
@@ -1,4 +1,4 @@
-#![feature(return_position_impl_trait_in_trait, lint_reasons)]
+#![feature(lint_reasons)]
 
 use std::ops::Deref;
 
diff --git a/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit-2.rs b/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit-2.rs
index 3a93dfee5..41d5f0f64 100644
--- a/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit-2.rs
+++ b/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit-2.rs
@@ -1,6 +1,5 @@
 // issue: 114146
 
-#![feature(return_position_impl_trait_in_trait)]
 
 trait Foo {
     fn bar<'other: 'a>() -> impl Sized + 'a {}
diff --git a/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit-2.stderr b/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit-2.stderr
index 3a1f8f908..b0832eb33 100644
--- a/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit-2.stderr
+++ b/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit-2.stderr
@@ -1,5 +1,5 @@
 error[E0261]: use of undeclared lifetime name `'a`
-  --> $DIR/bad-item-bound-within-rpitit-2.rs:6:20
+  --> $DIR/bad-item-bound-within-rpitit-2.rs:5:20
    |
 LL |     fn bar<'other: 'a>() -> impl Sized + 'a {}
    |                    ^^ undeclared lifetime
@@ -14,7 +14,7 @@ LL | trait Foo<'a> {
    |          ++++
 
 error[E0261]: use of undeclared lifetime name `'a`
-  --> $DIR/bad-item-bound-within-rpitit-2.rs:6:42
+  --> $DIR/bad-item-bound-within-rpitit-2.rs:5:42
    |
 LL |     fn bar<'other: 'a>() -> impl Sized + 'a {}
    |                                          ^^ undeclared lifetime
diff --git a/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.rs b/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.rs
index fbbbb8585..5ddc97f1a 100644
--- a/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.rs
+++ b/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.rs
@@ -1,6 +1,5 @@
 // issue: 114145
 
-#![feature(return_position_impl_trait_in_trait)]
 
 pub trait Iterable {
     type Item<'a>
diff --git a/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.stderr b/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.stderr
index a5fb338ea..324eaa37a 100644
--- a/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.stderr
+++ b/tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.stderr
@@ -1,5 +1,5 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/bad-item-bound-within-rpitit.rs:16:13
+  --> $DIR/bad-item-bound-within-rpitit.rs:15:13
    |
 LL |     type Item<'a>
    |     ------------- definition of `Item` from trait
@@ -13,7 +13,7 @@ LL |     where Self: 'b;
    |     ~~~~~~~~~~~~~~
 
 warning: impl trait in impl method signature does not match trait method signature
-  --> $DIR/bad-item-bound-within-rpitit.rs:19:28
+  --> $DIR/bad-item-bound-within-rpitit.rs:18:28
    |
 LL |     fn iter(&self) -> impl '_ + Iterator<Item = Self::Item<'_>>;
    |                       ----------------------------------------- return type from trait method defined here
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 f5ee4690f..87eb7beb1 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
@@ -1,6 +1,5 @@
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait)]
 
 struct TestA {}
 struct TestB {}
diff --git a/tests/ui/impl-trait/in-trait/check-wf-on-non-defaulted-rpitit.rs b/tests/ui/impl-trait/in-trait/check-wf-on-non-defaulted-rpitit.rs
index 742537ffc..2845b401b 100644
--- a/tests/ui/impl-trait/in-trait/check-wf-on-non-defaulted-rpitit.rs
+++ b/tests/ui/impl-trait/in-trait/check-wf-on-non-defaulted-rpitit.rs
@@ -1,5 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-
 struct Wrapper<G: Send>(G);
 
 trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/check-wf-on-non-defaulted-rpitit.stderr b/tests/ui/impl-trait/in-trait/check-wf-on-non-defaulted-rpitit.stderr
index dee87d082..1570b2ecd 100644
--- a/tests/ui/impl-trait/in-trait/check-wf-on-non-defaulted-rpitit.stderr
+++ b/tests/ui/impl-trait/in-trait/check-wf-on-non-defaulted-rpitit.stderr
@@ -1,12 +1,12 @@
 error[E0277]: `impl Sized` cannot be sent between threads safely
-  --> $DIR/check-wf-on-non-defaulted-rpitit.rs:6:17
+  --> $DIR/check-wf-on-non-defaulted-rpitit.rs:4:17
    |
 LL |     fn bar() -> Wrapper<impl Sized>;
    |                 ^^^^^^^^^^^^^^^^^^^ `impl Sized` cannot be sent between threads safely
    |
    = help: the trait `Send` is not implemented for `impl Sized`
 note: required by a bound in `Wrapper`
-  --> $DIR/check-wf-on-non-defaulted-rpitit.rs:3:19
+  --> $DIR/check-wf-on-non-defaulted-rpitit.rs:1:19
    |
 LL | struct Wrapper<G: Send>(G);
    |                   ^^^^ required by this bound in `Wrapper`
diff --git a/tests/ui/impl-trait/in-trait/deep-match-works.rs b/tests/ui/impl-trait/in-trait/deep-match-works.rs
index fc290f11f..8c9927438 100644
--- a/tests/ui/impl-trait/in-trait/deep-match-works.rs
+++ b/tests/ui/impl-trait/in-trait/deep-match-works.rs
@@ -1,6 +1,6 @@
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait, lint_reasons)]
+#![feature(lint_reasons)]
 #![allow(incomplete_features)]
 
 pub struct Wrapper<T>(T);
diff --git a/tests/ui/impl-trait/in-trait/deep-match.rs b/tests/ui/impl-trait/in-trait/deep-match.rs
index 0cae88f34..82eac7760 100644
--- a/tests/ui/impl-trait/in-trait/deep-match.rs
+++ b/tests/ui/impl-trait/in-trait/deep-match.rs
@@ -1,6 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-#![allow(incomplete_features)]
-
 struct Wrapper<T>(T);
 
 trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/deep-match.stderr b/tests/ui/impl-trait/in-trait/deep-match.stderr
index f0ad3c16e..a658d8fa0 100644
--- a/tests/ui/impl-trait/in-trait/deep-match.stderr
+++ b/tests/ui/impl-trait/in-trait/deep-match.stderr
@@ -1,5 +1,5 @@
 error[E0053]: method `bar` has an incompatible return type for trait
-  --> $DIR/deep-match.rs:11:17
+  --> $DIR/deep-match.rs:8:17
    |
 LL |     fn bar() -> i32 {
    |                 ^^^
diff --git a/tests/ui/impl-trait/in-trait/default-body-type-err-2.rs b/tests/ui/impl-trait/in-trait/default-body-type-err-2.rs
index 45ae2b8ad..29bcbe16d 100644
--- a/tests/ui/impl-trait/in-trait/default-body-type-err-2.rs
+++ b/tests/ui/impl-trait/in-trait/default-body-type-err-2.rs
@@ -1,7 +1,6 @@
 // edition:2021
 
 #![allow(incomplete_features)]
-#![feature(async_fn_in_trait)]
 
 pub trait Foo {
     async fn woopsie_async(&self) -> String {
diff --git a/tests/ui/impl-trait/in-trait/default-body-type-err-2.stderr b/tests/ui/impl-trait/in-trait/default-body-type-err-2.stderr
index cc3bdf0e5..fcace10cd 100644
--- a/tests/ui/impl-trait/in-trait/default-body-type-err-2.stderr
+++ b/tests/ui/impl-trait/in-trait/default-body-type-err-2.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/default-body-type-err-2.rs:8:9
+  --> $DIR/default-body-type-err-2.rs:7:9
    |
 LL |         42
    |         ^^- help: try using a conversion method: `.to_string()`
diff --git a/tests/ui/impl-trait/in-trait/default-body-type-err.rs b/tests/ui/impl-trait/in-trait/default-body-type-err.rs
index ac9baf91c..ac7a50a36 100644
--- a/tests/ui/impl-trait/in-trait/default-body-type-err.rs
+++ b/tests/ui/impl-trait/in-trait/default-body-type-err.rs
@@ -1,6 +1,3 @@
-#![allow(incomplete_features)]
-#![feature(return_position_impl_trait_in_trait)]
-
 use std::ops::Deref;
 
 pub trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/default-body-type-err.stderr b/tests/ui/impl-trait/in-trait/default-body-type-err.stderr
index 4742eb37d..596ff1011 100644
--- a/tests/ui/impl-trait/in-trait/default-body-type-err.stderr
+++ b/tests/ui/impl-trait/in-trait/default-body-type-err.stderr
@@ -1,5 +1,5 @@
 error[E0271]: type mismatch resolving `<&i32 as Deref>::Target == String`
-  --> $DIR/default-body-type-err.rs:7:22
+  --> $DIR/default-body-type-err.rs:4:22
    |
 LL |     fn lol(&self) -> impl Deref<Target = String> {
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `String`
diff --git a/tests/ui/impl-trait/in-trait/default-body-with-rpit.rs b/tests/ui/impl-trait/in-trait/default-body-with-rpit.rs
index 25133214d..1d1f55508 100644
--- a/tests/ui/impl-trait/in-trait/default-body-with-rpit.rs
+++ b/tests/ui/impl-trait/in-trait/default-body-with-rpit.rs
@@ -1,12 +1,12 @@
 // edition:2021
 // check-pass
 
-#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
 #![allow(incomplete_features)]
 
 use std::fmt::Debug;
 
 trait Foo {
+    #[allow(async_fn_in_trait)]
     async fn baz(&self) -> impl Debug {
         ""
     }
diff --git a/tests/ui/impl-trait/in-trait/default-body.rs b/tests/ui/impl-trait/in-trait/default-body.rs
index b0baf5bb1..ff70f1e23 100644
--- a/tests/ui/impl-trait/in-trait/default-body.rs
+++ b/tests/ui/impl-trait/in-trait/default-body.rs
@@ -1,12 +1,12 @@
 // check-pass
 // edition:2021
 
-#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
 #![allow(incomplete_features)]
 
 use std::fmt::Debug;
 
 trait Foo {
+    #[allow(async_fn_in_trait)]
     async fn baz(&self) -> &str {
         ""
     }
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 817a4d7db..ca41eb8bc 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
@@ -1,6 +1,5 @@
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait)]
 
 trait Trait {
     type Type;
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 28d76241f..8ab2e2797 100644
--- a/tests/ui/impl-trait/in-trait/default-method-constraint.rs
+++ b/tests/ui/impl-trait/in-trait/default-method-constraint.rs
@@ -2,7 +2,6 @@
 
 // This didn't work in the previous default RPITIT method hack attempt
 
-#![feature(return_position_impl_trait_in_trait)]
 
 trait Foo {
     fn bar(x: bool) -> impl Sized {
diff --git a/tests/ui/impl-trait/in-trait/doesnt-satisfy.rs b/tests/ui/impl-trait/in-trait/doesnt-satisfy.rs
index bb4e0d44f..0ac60918b 100644
--- a/tests/ui/impl-trait/in-trait/doesnt-satisfy.rs
+++ b/tests/ui/impl-trait/in-trait/doesnt-satisfy.rs
@@ -1,6 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-#![allow(incomplete_features)]
-
 trait Foo {
     fn bar() -> impl std::fmt::Display;
 }
diff --git a/tests/ui/impl-trait/in-trait/doesnt-satisfy.stderr b/tests/ui/impl-trait/in-trait/doesnt-satisfy.stderr
index 7c56ffa10..cd45c6a9c 100644
--- a/tests/ui/impl-trait/in-trait/doesnt-satisfy.stderr
+++ b/tests/ui/impl-trait/in-trait/doesnt-satisfy.stderr
@@ -1,5 +1,5 @@
 error[E0277]: `()` doesn't implement `std::fmt::Display`
-  --> $DIR/doesnt-satisfy.rs:9:17
+  --> $DIR/doesnt-satisfy.rs:6:17
    |
 LL |     fn bar() -> () {}
    |                 ^^ `()` cannot be formatted with the default formatter
@@ -7,7 +7,7 @@ LL |     fn bar() -> () {}
    = help: the trait `std::fmt::Display` is not implemented for `()`
    = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
 note: required by a bound in `Foo::{opaque#0}`
-  --> $DIR/doesnt-satisfy.rs:5:22
+  --> $DIR/doesnt-satisfy.rs:2:22
    |
 LL |     fn bar() -> impl std::fmt::Display;
    |                      ^^^^^^^^^^^^^^^^^ required by this bound in `Foo::{opaque#0}`
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 4719d5d3c..fe0f011b6 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
@@ -1,5 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-
 trait MyTrait {
     fn foo(&self) -> impl Sized;
     fn bar(&self) -> impl Sized;
diff --git a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.stderr b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.stderr
index 66ee142cc..830e663da 100644
--- a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.stderr
+++ b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.stderr
@@ -1,5 +1,5 @@
 error[E0046]: not all trait items implemented, missing: `foo`
-  --> $DIR/dont-project-to-rpitit-with-no-value.rs:8:1
+  --> $DIR/dont-project-to-rpitit-with-no-value.rs:6:1
    |
 LL |     fn foo(&self) -> impl Sized;
    |     ---------------------------- `foo` from trait
diff --git a/tests/ui/impl-trait/in-trait/early.rs b/tests/ui/impl-trait/in-trait/early.rs
index 9c1c2b503..c4996674d 100644
--- a/tests/ui/impl-trait/in-trait/early.rs
+++ b/tests/ui/impl-trait/in-trait/early.rs
@@ -1,10 +1,10 @@
 // check-pass
 // edition:2021
 
-#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
 #![allow(incomplete_features)]
 
 pub trait Foo {
+    #[allow(async_fn_in_trait)]
     async fn bar<'a: 'a>(&'a mut self);
 }
 
diff --git a/tests/ui/impl-trait/in-trait/encode.rs b/tests/ui/impl-trait/in-trait/encode.rs
index efb9f6498..4df26b0f2 100644
--- a/tests/ui/impl-trait/in-trait/encode.rs
+++ b/tests/ui/impl-trait/in-trait/encode.rs
@@ -1,7 +1,6 @@
 // build-pass
 // compile-flags: --crate-type=lib
 
-#![feature(return_position_impl_trait_in_trait)]
 #![allow(incomplete_features)]
 
 trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr b/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr
index bfb2be8cb..f29ec95d5 100644
--- a/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr
+++ b/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr
@@ -9,6 +9,7 @@ note: for a trait to be "object safe" it needs to allow building a vtable to all
    |
 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
+   = help: only type `rpitit::Foreign` implements the trait, consider using it directly instead
 
 error: aborting due to previous error
 
diff --git a/tests/ui/impl-trait/in-trait/gat-outlives.rs b/tests/ui/impl-trait/in-trait/gat-outlives.rs
new file mode 100644
index 000000000..83dd6cfce
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/gat-outlives.rs
@@ -0,0 +1,17 @@
+// edition: 2021
+
+use std::future::Future;
+
+trait Trait {
+    type Gat<'a>;
+    //~^ ERROR missing required bound on `Gat`
+    async fn foo(&self) -> Self::Gat<'_>;
+}
+
+trait Trait2 {
+    type Gat<'a>;
+    //~^ ERROR missing required bound on `Gat`
+    async fn foo(&self) -> impl Future<Output = Self::Gat<'_>>;
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/in-trait/gat-outlives.stderr b/tests/ui/impl-trait/in-trait/gat-outlives.stderr
new file mode 100644
index 000000000..8ec4b0ab2
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/gat-outlives.stderr
@@ -0,0 +1,24 @@
+error: missing required bound on `Gat`
+  --> $DIR/gat-outlives.rs:6:5
+   |
+LL |     type Gat<'a>;
+   |     ^^^^^^^^^^^^-
+   |                 |
+   |                 help: add the required where clause: `where Self: 'a`
+   |
+   = note: this bound is currently required to ensure that impls have maximum flexibility
+   = note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
+
+error: missing required bound on `Gat`
+  --> $DIR/gat-outlives.rs:12:5
+   |
+LL |     type Gat<'a>;
+   |     ^^^^^^^^^^^^-
+   |                 |
+   |                 help: add the required where clause: `where Self: 'a`
+   |
+   = note: this bound is currently required to ensure that impls have maximum flexibility
+   = note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/impl-trait/in-trait/generics-mismatch.rs b/tests/ui/impl-trait/in-trait/generics-mismatch.rs
index cc0fc720e..3ea31cc93 100644
--- a/tests/ui/impl-trait/in-trait/generics-mismatch.rs
+++ b/tests/ui/impl-trait/in-trait/generics-mismatch.rs
@@ -1,6 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-#![allow(incomplete_features)]
-
 struct U;
 
 trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/generics-mismatch.stderr b/tests/ui/impl-trait/in-trait/generics-mismatch.stderr
index cd42683e0..043dbc8db 100644
--- a/tests/ui/impl-trait/in-trait/generics-mismatch.stderr
+++ b/tests/ui/impl-trait/in-trait/generics-mismatch.stderr
@@ -1,5 +1,5 @@
 error[E0049]: method `bar` has 1 type parameter but its trait declaration has 0 type parameters
-  --> $DIR/generics-mismatch.rs:11:12
+  --> $DIR/generics-mismatch.rs:8:12
    |
 LL |     fn bar(&self) -> impl Sized;
    |           - expected 0 type parameters
diff --git a/tests/ui/impl-trait/in-trait/issue-102140.rs b/tests/ui/impl-trait/in-trait/issue-102140.rs
index be1e012ac..796001848 100644
--- a/tests/ui/impl-trait/in-trait/issue-102140.rs
+++ b/tests/ui/impl-trait/in-trait/issue-102140.rs
@@ -1,6 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-#![allow(incomplete_features)]
-
 trait Marker {}
 impl Marker for u32 {}
 
diff --git a/tests/ui/impl-trait/in-trait/issue-102140.stderr b/tests/ui/impl-trait/in-trait/issue-102140.stderr
index 18bb63745..9cd2cdfd1 100644
--- a/tests/ui/impl-trait/in-trait/issue-102140.stderr
+++ b/tests/ui/impl-trait/in-trait/issue-102140.stderr
@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `&dyn MyTrait: MyTrait` is not satisfied
-  --> $DIR/issue-102140.rs:23:22
+  --> $DIR/issue-102140.rs:20:22
    |
 LL |         MyTrait::foo(&self)
    |         ------------ ^^^^^ the trait `MyTrait` is not implemented for `&dyn MyTrait`
@@ -13,7 +13,7 @@ LL +         MyTrait::foo(self)
    |
 
 error[E0277]: the trait bound `&dyn MyTrait: MyTrait` is not satisfied
-  --> $DIR/issue-102140.rs:23:9
+  --> $DIR/issue-102140.rs:20:9
    |
 LL |         MyTrait::foo(&self)
    |         ^^^^^^^^^^^^^^^^^^^ the trait `MyTrait` is not implemented for `&dyn MyTrait`
@@ -21,7 +21,7 @@ LL |         MyTrait::foo(&self)
    = 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
+  --> $DIR/issue-102140.rs:20:9
    |
 LL |         MyTrait::foo(&self)
    |         ^^^^^^^^^^^^ the trait `MyTrait` is not implemented for `&dyn MyTrait`
diff --git a/tests/ui/impl-trait/in-trait/issue-102301.rs b/tests/ui/impl-trait/in-trait/issue-102301.rs
index a93714a65..600a21b07 100644
--- a/tests/ui/impl-trait/in-trait/issue-102301.rs
+++ b/tests/ui/impl-trait/in-trait/issue-102301.rs
@@ -1,6 +1,5 @@
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait)]
 #![allow(incomplete_features)]
 
 trait Foo<T> {
diff --git a/tests/ui/impl-trait/in-trait/issue-102571.rs b/tests/ui/impl-trait/in-trait/issue-102571.rs
index ccb53031c..4fa3fdd31 100644
--- a/tests/ui/impl-trait/in-trait/issue-102571.rs
+++ b/tests/ui/impl-trait/in-trait/issue-102571.rs
@@ -1,6 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-#![allow(incomplete_features)]
-
 use std::fmt::Display;
 use std::ops::Deref;
 
diff --git a/tests/ui/impl-trait/in-trait/issue-102571.stderr b/tests/ui/impl-trait/in-trait/issue-102571.stderr
index 594b9ae9c..872988faf 100644
--- a/tests/ui/impl-trait/in-trait/issue-102571.stderr
+++ b/tests/ui/impl-trait/in-trait/issue-102571.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/issue-102571.rs:12:9
+  --> $DIR/issue-102571.rs:9:9
    |
 LL |     let () = t.bar();
    |         ^^   ------- this expression has type `impl Deref<Target = impl std::fmt::Display + ?Sized>`
diff --git a/tests/ui/impl-trait/in-trait/lifetime-in-associated-trait-bound.rs b/tests/ui/impl-trait/in-trait/lifetime-in-associated-trait-bound.rs
index 49d36d6c9..4073ef8ac 100644
--- a/tests/ui/impl-trait/in-trait/lifetime-in-associated-trait-bound.rs
+++ b/tests/ui/impl-trait/in-trait/lifetime-in-associated-trait-bound.rs
@@ -1,6 +1,6 @@
 // check-pass
 
-#![feature(associated_type_bounds, return_position_impl_trait_in_trait)]
+#![feature(associated_type_bounds)]
 
 trait Trait {
     type Type;
diff --git a/tests/ui/impl-trait/in-trait/method-signature-matches.lt.stderr b/tests/ui/impl-trait/in-trait/method-signature-matches.lt.stderr
index 239c4b35c..874a1b95a 100644
--- a/tests/ui/impl-trait/in-trait/method-signature-matches.lt.stderr
+++ b/tests/ui/impl-trait/in-trait/method-signature-matches.lt.stderr
@@ -1,15 +1,15 @@
 error[E0053]: method `early` has an incompatible type for trait
-  --> $DIR/method-signature-matches.rs:58:27
+  --> $DIR/method-signature-matches.rs:57:27
    |
 LL |     fn early<'late, T>(_: &'late ()) {}
    |                     -     ^^^^^^^^^
    |                     |     |
    |                     |     expected type parameter `T`, found `()`
    |                     |     help: change the parameter type to match the trait: `&T`
-   |                     this type parameter
+   |                     expected this type parameter
    |
 note: type in trait
-  --> $DIR/method-signature-matches.rs:53:28
+  --> $DIR/method-signature-matches.rs:52:28
    |
 LL |     fn early<'early, T>(x: &'early T) -> impl Sized;
    |                            ^^^^^^^^^
diff --git a/tests/ui/impl-trait/in-trait/method-signature-matches.mismatch.stderr b/tests/ui/impl-trait/in-trait/method-signature-matches.mismatch.stderr
index d3183b92e..e0bd1cc4f 100644
--- a/tests/ui/impl-trait/in-trait/method-signature-matches.mismatch.stderr
+++ b/tests/ui/impl-trait/in-trait/method-signature-matches.mismatch.stderr
@@ -1,5 +1,5 @@
 error[E0053]: method `owo` has an incompatible type for trait
-  --> $DIR/method-signature-matches.rs:14:15
+  --> $DIR/method-signature-matches.rs:13:15
    |
 LL |     fn owo(_: u8) {}
    |               ^^
@@ -8,7 +8,7 @@ LL |     fn owo(_: u8) {}
    |               help: change the parameter type to match the trait: `()`
    |
 note: type in trait
-  --> $DIR/method-signature-matches.rs:9:15
+  --> $DIR/method-signature-matches.rs:8:15
    |
 LL |     fn owo(x: ()) -> impl Sized;
    |               ^^
diff --git a/tests/ui/impl-trait/in-trait/method-signature-matches.mismatch_async.stderr b/tests/ui/impl-trait/in-trait/method-signature-matches.mismatch_async.stderr
index 80fda1c9f..096e96c85 100644
--- a/tests/ui/impl-trait/in-trait/method-signature-matches.mismatch_async.stderr
+++ b/tests/ui/impl-trait/in-trait/method-signature-matches.mismatch_async.stderr
@@ -1,5 +1,5 @@
 error[E0053]: method `owo` has an incompatible type for trait
-  --> $DIR/method-signature-matches.rs:25:21
+  --> $DIR/method-signature-matches.rs:24:21
    |
 LL |     async fn owo(_: u8) {}
    |                     ^^
@@ -8,7 +8,7 @@ LL |     async fn owo(_: u8) {}
    |                     help: change the parameter type to match the trait: `()`
    |
 note: type in trait
-  --> $DIR/method-signature-matches.rs:20:21
+  --> $DIR/method-signature-matches.rs:19:21
    |
 LL |     async fn owo(x: ()) {}
    |                     ^^
diff --git a/tests/ui/impl-trait/in-trait/method-signature-matches.rs b/tests/ui/impl-trait/in-trait/method-signature-matches.rs
index 294f93b30..99ace66fa 100644
--- a/tests/ui/impl-trait/in-trait/method-signature-matches.rs
+++ b/tests/ui/impl-trait/in-trait/method-signature-matches.rs
@@ -1,7 +1,6 @@
 // edition: 2021
 // revisions: mismatch mismatch_async too_many too_few lt
 
-#![feature(return_position_impl_trait_in_trait, async_fn_in_trait)]
 #![allow(incomplete_features)]
 
 #[cfg(mismatch)]
diff --git a/tests/ui/impl-trait/in-trait/method-signature-matches.too_few.stderr b/tests/ui/impl-trait/in-trait/method-signature-matches.too_few.stderr
index 24bcfeb74..96eff1a58 100644
--- a/tests/ui/impl-trait/in-trait/method-signature-matches.too_few.stderr
+++ b/tests/ui/impl-trait/in-trait/method-signature-matches.too_few.stderr
@@ -1,5 +1,5 @@
 error[E0050]: method `come_on_a_little_more_effort` has 0 parameters but the declaration in trait `TooLittle::come_on_a_little_more_effort` has 3
-  --> $DIR/method-signature-matches.rs:47:5
+  --> $DIR/method-signature-matches.rs:46:5
    |
 LL |     fn come_on_a_little_more_effort(_: (), _: (), _: ()) -> impl Sized;
    |                                        ---------------- trait requires 3 parameters
diff --git a/tests/ui/impl-trait/in-trait/method-signature-matches.too_many.stderr b/tests/ui/impl-trait/in-trait/method-signature-matches.too_many.stderr
index 616cbd290..0fc847051 100644
--- a/tests/ui/impl-trait/in-trait/method-signature-matches.too_many.stderr
+++ b/tests/ui/impl-trait/in-trait/method-signature-matches.too_many.stderr
@@ -1,5 +1,5 @@
 error[E0050]: method `calm_down_please` has 3 parameters but the declaration in trait `TooMuch::calm_down_please` has 0
-  --> $DIR/method-signature-matches.rs:36:28
+  --> $DIR/method-signature-matches.rs:35:28
    |
 LL |     fn calm_down_please() -> impl Sized;
    |     ------------------------------------ trait requires 0 parameters
diff --git a/tests/ui/impl-trait/in-trait/missing-lt-outlives-in-rpitit-114274.rs b/tests/ui/impl-trait/in-trait/missing-lt-outlives-in-rpitit-114274.rs
index abc845d3a..6088dcc61 100644
--- a/tests/ui/impl-trait/in-trait/missing-lt-outlives-in-rpitit-114274.rs
+++ b/tests/ui/impl-trait/in-trait/missing-lt-outlives-in-rpitit-114274.rs
@@ -1,5 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-
 trait Iterable {
     type Item<'a>
     where
diff --git a/tests/ui/impl-trait/in-trait/missing-lt-outlives-in-rpitit-114274.stderr b/tests/ui/impl-trait/in-trait/missing-lt-outlives-in-rpitit-114274.stderr
index 0d74c0b69..1fd678a1f 100644
--- a/tests/ui/impl-trait/in-trait/missing-lt-outlives-in-rpitit-114274.stderr
+++ b/tests/ui/impl-trait/in-trait/missing-lt-outlives-in-rpitit-114274.stderr
@@ -1,5 +1,5 @@
 error[E0261]: use of undeclared lifetime name `'missing`
-  --> $DIR/missing-lt-outlives-in-rpitit-114274.rs:8:55
+  --> $DIR/missing-lt-outlives-in-rpitit-114274.rs:6:55
    |
 LL |     fn iter(&self) -> impl Iterator<Item = Self::Item<'missing>>;
    |                                                       ^^^^^^^^ undeclared lifetime
diff --git a/tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs b/tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs
new file mode 100644
index 000000000..b97fd7d1f
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs
@@ -0,0 +1,11 @@
+// check-pass
+
+use std::ops::Deref;
+
+trait Foo {
+    fn foo() -> impl Deref<Target = impl Deref<Target = impl Sized>> {
+        &&()
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/in-trait/nested-rpitit.rs b/tests/ui/impl-trait/in-trait/nested-rpitit.rs
index 58ba1acaf..58b79c991 100644
--- a/tests/ui/impl-trait/in-trait/nested-rpitit.rs
+++ b/tests/ui/impl-trait/in-trait/nested-rpitit.rs
@@ -1,6 +1,6 @@
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait, lint_reasons)]
+#![feature(lint_reasons)]
 #![allow(incomplete_features)]
 
 use std::fmt::Display;
diff --git a/tests/ui/impl-trait/in-trait/object-safety-sized.rs b/tests/ui/impl-trait/in-trait/object-safety-sized.rs
index f221cfbb1..35afe80c9 100644
--- a/tests/ui/impl-trait/in-trait/object-safety-sized.rs
+++ b/tests/ui/impl-trait/in-trait/object-safety-sized.rs
@@ -2,7 +2,6 @@
 // revisions: current next
 //[next] compile-flags: -Ztrait-solver=next
 
-#![feature(return_position_impl_trait_in_trait)]
 
 fn main() {
     let vec: Vec<Box<dyn Trait>> = Vec::new();
diff --git a/tests/ui/impl-trait/in-trait/object-safety.rs b/tests/ui/impl-trait/in-trait/object-safety.rs
index d1c9fba4e..5cca4ad83 100644
--- a/tests/ui/impl-trait/in-trait/object-safety.rs
+++ b/tests/ui/impl-trait/in-trait/object-safety.rs
@@ -1,6 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-#![allow(incomplete_features)]
-
 use std::fmt::Debug;
 
 trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/object-safety.stderr b/tests/ui/impl-trait/in-trait/object-safety.stderr
index 0170dc5d0..a7be0516c 100644
--- a/tests/ui/impl-trait/in-trait/object-safety.stderr
+++ b/tests/ui/impl-trait/in-trait/object-safety.stderr
@@ -1,62 +1,66 @@
 error[E0038]: the trait `Foo` cannot be made into an object
-  --> $DIR/object-safety.rs:17:33
+  --> $DIR/object-safety.rs:14:33
    |
 LL |     let i = Box::new(42_u32) as Box<dyn Foo>;
    |                                 ^^^^^^^^^^^^ `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/object-safety.rs:7:22
+  --> $DIR/object-safety.rs:4:22
    |
 LL | trait Foo {
    |       --- this trait cannot be made into an object...
 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
+   = help: only type `u32` implements the trait, consider using it directly instead
 
 error[E0038]: the trait `Foo` cannot be made into an object
-  --> $DIR/object-safety.rs:20:15
+  --> $DIR/object-safety.rs:17:15
    |
 LL |     let s = i.baz();
    |               ^^^ `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/object-safety.rs:7:22
+  --> $DIR/object-safety.rs:4:22
    |
 LL | trait Foo {
    |       --- this trait cannot be made into an object...
 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
+   = help: only type `u32` implements the trait, consider using it directly instead
 
 error[E0038]: the trait `Foo` cannot be made into an object
-  --> $DIR/object-safety.rs:20:13
+  --> $DIR/object-safety.rs:17:13
    |
 LL |     let s = i.baz();
    |             ^^^^^^^ `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/object-safety.rs:7:22
+  --> $DIR/object-safety.rs:4:22
    |
 LL | trait Foo {
    |       --- this trait cannot be made into an object...
 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
+   = help: only type `u32` implements the trait, consider using it directly instead
 
 error[E0038]: the trait `Foo` cannot be made into an object
-  --> $DIR/object-safety.rs:17:13
+  --> $DIR/object-safety.rs:14:13
    |
 LL |     let i = Box::new(42_u32) as Box<dyn Foo>;
    |             ^^^^^^^^^^^^^^^^ `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/object-safety.rs:7:22
+  --> $DIR/object-safety.rs:4:22
    |
 LL | trait Foo {
    |       --- this trait cannot be made into an object...
 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
+   = help: only type `u32` implements the trait, consider using it directly instead
    = note: required for the cast from `Box<u32>` to `Box<dyn Foo>`
 
 error: aborting due to 4 previous errors
diff --git a/tests/ui/impl-trait/in-trait/opaque-in-impl-is-opaque.rs b/tests/ui/impl-trait/in-trait/opaque-in-impl-is-opaque.rs
index 3ac264e8e..1f18bb3b7 100644
--- a/tests/ui/impl-trait/in-trait/opaque-in-impl-is-opaque.rs
+++ b/tests/ui/impl-trait/in-trait/opaque-in-impl-is-opaque.rs
@@ -1,6 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-#![allow(incomplete_features)]
-
 use std::fmt::Display;
 
 trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/opaque-in-impl-is-opaque.stderr b/tests/ui/impl-trait/in-trait/opaque-in-impl-is-opaque.stderr
index 15edda483..e260762d8 100644
--- a/tests/ui/impl-trait/in-trait/opaque-in-impl-is-opaque.stderr
+++ b/tests/ui/impl-trait/in-trait/opaque-in-impl-is-opaque.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/opaque-in-impl-is-opaque.rs:17:19
+  --> $DIR/opaque-in-impl-is-opaque.rs:14:19
    |
 LL |     fn bar(&self) -> impl Display {
    |                      ------------ the found opaque type
diff --git a/tests/ui/impl-trait/in-trait/opaque-in-impl.rs b/tests/ui/impl-trait/in-trait/opaque-in-impl.rs
index 2e0662969..3edd588a1 100644
--- a/tests/ui/impl-trait/in-trait/opaque-in-impl.rs
+++ b/tests/ui/impl-trait/in-trait/opaque-in-impl.rs
@@ -1,6 +1,5 @@
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait)]
 #![allow(incomplete_features)]
 
 use std::fmt::Debug;
diff --git a/tests/ui/impl-trait/in-trait/opaque-variances.rs b/tests/ui/impl-trait/in-trait/opaque-variances.rs
new file mode 100644
index 000000000..60bfab0de
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/opaque-variances.rs
@@ -0,0 +1,14 @@
+// check-pass
+// compile-flags: -Ztrait-solver=next
+
+fn foo<'a: 'a>(x: &'a Vec<i32>) -> impl Sized {
+    ()
+}
+
+fn main() {
+    // in NLL, we want to make sure that the `'a` subst of `foo` does not get
+    // related between `x` and the RHS of the assignment. That would require
+    // that the temp is live for the lifetime of the variable `x`, which of
+    // course is not necessary since `'a` is not captured by the RPIT.
+    let x = foo(&Vec::new());
+}
diff --git a/tests/ui/impl-trait/in-trait/outlives-in-nested-rpit.rs b/tests/ui/impl-trait/in-trait/outlives-in-nested-rpit.rs
index 6330242ce..317ff7fe8 100644
--- a/tests/ui/impl-trait/in-trait/outlives-in-nested-rpit.rs
+++ b/tests/ui/impl-trait/in-trait/outlives-in-nested-rpit.rs
@@ -1,6 +1,5 @@
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait)]
 
 trait Foo {
     fn early<'a, T: 'a>(x: &'a T) -> impl Iterator<Item = impl Into<&'a T>>;
diff --git a/tests/ui/impl-trait/in-trait/refine.rs b/tests/ui/impl-trait/in-trait/refine.rs
index a91f9b3e7..100e6da06 100644
--- a/tests/ui/impl-trait/in-trait/refine.rs
+++ b/tests/ui/impl-trait/in-trait/refine.rs
@@ -1,4 +1,3 @@
-#![feature(return_position_impl_trait_in_trait, async_fn_in_trait)]
 #![deny(refining_impl_trait)]
 
 pub trait Foo {
@@ -45,4 +44,15 @@ impl Late for D {
     //~^ ERROR impl method signature does not match trait method signature
 }
 
+mod unreachable {
+    pub trait UnreachablePub {
+        fn bar() -> impl Sized;
+    }
+
+    struct E;
+    impl UnreachablePub for E {
+        fn bar() {}
+    }
+}
+
 fn main() {}
diff --git a/tests/ui/impl-trait/in-trait/refine.stderr b/tests/ui/impl-trait/in-trait/refine.stderr
index 29aa08e25..96a9bc059 100644
--- a/tests/ui/impl-trait/in-trait/refine.stderr
+++ b/tests/ui/impl-trait/in-trait/refine.stderr
@@ -1,5 +1,5 @@
 error: impl trait in impl method signature does not match trait method signature
-  --> $DIR/refine.rs:10:22
+  --> $DIR/refine.rs:9:22
    |
 LL |     fn bar() -> impl Sized;
    |                 ---------- return type from trait method defined here
@@ -9,7 +9,7 @@ LL |     fn bar() -> impl Copy {}
    |
    = note: add `#[allow(refining_impl_trait)]` if it is intended for this to be part of the public API of this crate
 note: the lint level is defined here
-  --> $DIR/refine.rs:2:9
+  --> $DIR/refine.rs:1:9
    |
 LL | #![deny(refining_impl_trait)]
    |         ^^^^^^^^^^^^^^^^^^^
@@ -19,7 +19,7 @@ LL |     fn bar() -> impl Sized {}
    |                 ~~~~~~~~~~
 
 error: impl trait in impl method signature does not match trait method signature
-  --> $DIR/refine.rs:16:5
+  --> $DIR/refine.rs:15:5
    |
 LL |     fn bar() -> impl Sized;
    |                 ---------- return type from trait method defined here
@@ -30,11 +30,11 @@ LL |     fn bar() {}
    = note: add `#[allow(refining_impl_trait)]` if it is intended for this to be part of the public API of this crate
 help: replace the return type so that it matches the trait
    |
-LL |     fn bar() -> impl Sized {}
-   |              +++++++++++++
+LL |     fn bar()-> impl Sized  {}
+   |             +++++++++++++
 
 error: impl trait in impl method signature does not match trait method signature
-  --> $DIR/refine.rs:22:17
+  --> $DIR/refine.rs:21:17
    |
 LL |     fn bar() -> impl Sized;
    |                 ---------- return type from trait method defined here
@@ -49,7 +49,7 @@ LL |     fn bar() -> impl Sized {}
    |                 ~~~~~~~~~~
 
 error: impl trait in impl method signature does not match trait method signature
-  --> $DIR/refine.rs:44:27
+  --> $DIR/refine.rs:43:27
    |
 LL |     fn bar<'a>(&'a self) -> impl Sized + 'a;
    |                             --------------- return type from trait method defined here
diff --git a/tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.rs b/tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.rs
index 5d9a224cc..ad73b12fe 100644
--- a/tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.rs
+++ b/tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.rs
@@ -1,5 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-
 trait Foo<T> {
     fn foo<F2>(self) -> impl Foo<T>;
 }
diff --git a/tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.stderr b/tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.stderr
index 668fc6cbe..181d6a284 100644
--- a/tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.stderr
+++ b/tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.stderr
@@ -1,12 +1,12 @@
 error[E0277]: the trait bound `impl Foo<u8>: Foo<char>` is not satisfied
-  --> $DIR/return-dont-satisfy-bounds.rs:10:34
+  --> $DIR/return-dont-satisfy-bounds.rs:8:34
    |
 LL |     fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {
    |                                  ^^^^^^^^^^^^ the trait `Foo<char>` is not implemented for `impl Foo<u8>`
    |
    = help: the trait `Foo<char>` is implemented for `Bar`
 note: required by a bound in `Foo::{opaque#0}`
-  --> $DIR/return-dont-satisfy-bounds.rs:4:30
+  --> $DIR/return-dont-satisfy-bounds.rs:2:30
    |
 LL |     fn foo<F2>(self) -> impl Foo<T>;
    |                              ^^^^^^ required by this bound in `Foo::{opaque#0}`
diff --git a/tests/ui/impl-trait/in-trait/reveal.rs b/tests/ui/impl-trait/in-trait/reveal.rs
index b1b46d75b..cc78ce8fe 100644
--- a/tests/ui/impl-trait/in-trait/reveal.rs
+++ b/tests/ui/impl-trait/in-trait/reveal.rs
@@ -1,6 +1,6 @@
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait, lint_reasons)]
+#![feature(lint_reasons)]
 #![allow(incomplete_features)]
 
 pub trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf-via-param.rs b/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf-via-param.rs
index 5e14a7f8e..37b0b2297 100644
--- a/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf-via-param.rs
+++ b/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf-via-param.rs
@@ -1,5 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-
 trait Extend {
     fn extend<'a: 'a>(_: &'a str) -> (impl Sized + 'a, &'static str);
 }
diff --git a/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf-via-param.stderr b/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf-via-param.stderr
index 1d947310e..afc59cc5b 100644
--- a/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf-via-param.stderr
+++ b/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf-via-param.stderr
@@ -1,12 +1,12 @@
 error[E0491]: in type `&'static &'a ()`, reference has a longer lifetime than the data it references
-  --> $DIR/rpitit-hidden-types-self-implied-wf-via-param.rs:8:38
+  --> $DIR/rpitit-hidden-types-self-implied-wf-via-param.rs:6:38
    |
 LL |     fn extend<'a: 'a>(s: &'a str) -> (Option<&'static &'a ()>, &'static str)
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: the pointer is valid for the static lifetime
 note: but the referenced data is only valid for the lifetime `'a` as defined here
-  --> $DIR/rpitit-hidden-types-self-implied-wf-via-param.rs:8:15
+  --> $DIR/rpitit-hidden-types-self-implied-wf-via-param.rs:6:15
    |
 LL |     fn extend<'a: 'a>(s: &'a str) -> (Option<&'static &'a ()>, &'static str)
    |               ^^
diff --git a/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf.rs b/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf.rs
index c1885af4e..bacd50077 100644
--- a/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf.rs
+++ b/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf.rs
@@ -1,5 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-
 trait Extend {
     fn extend(_: &str) -> (impl Sized + '_, &'static str);
 }
diff --git a/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf.stderr b/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf.stderr
index 7b63e72ac..7e1a8f083 100644
--- a/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf.stderr
+++ b/tests/ui/impl-trait/in-trait/rpitit-hidden-types-self-implied-wf.stderr
@@ -1,12 +1,12 @@
 error[E0491]: in type `&'static &()`, reference has a longer lifetime than the data it references
-  --> $DIR/rpitit-hidden-types-self-implied-wf.rs:8:27
+  --> $DIR/rpitit-hidden-types-self-implied-wf.rs:6:27
    |
 LL |     fn extend(s: &str) -> (Option<&'static &'_ ()>, &'static str) {
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: the pointer is valid for the static lifetime
 note: but the referenced data is only valid for the anonymous lifetime defined here
-  --> $DIR/rpitit-hidden-types-self-implied-wf.rs:8:18
+  --> $DIR/rpitit-hidden-types-self-implied-wf.rs:6:18
    |
 LL |     fn extend(s: &str) -> (Option<&'static &'_ ()>, &'static str) {
    |                  ^^^^
diff --git a/tests/ui/impl-trait/in-trait/rpitit-shadowed-by-missing-adt.rs b/tests/ui/impl-trait/in-trait/rpitit-shadowed-by-missing-adt.rs
index 44a2b4303..b9fe8d8bf 100644
--- a/tests/ui/impl-trait/in-trait/rpitit-shadowed-by-missing-adt.rs
+++ b/tests/ui/impl-trait/in-trait/rpitit-shadowed-by-missing-adt.rs
@@ -1,6 +1,6 @@
 // issue: 113903
 
-#![feature(return_position_impl_trait_in_trait, lint_reasons)]
+#![feature(lint_reasons)]
 
 use std::ops::Deref;
 
diff --git a/tests/ui/impl-trait/in-trait/sibling-function-constraint.rs b/tests/ui/impl-trait/in-trait/sibling-function-constraint.rs
new file mode 100644
index 000000000..fe162e6cf
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/sibling-function-constraint.rs
@@ -0,0 +1,21 @@
+// Checks that a sibling function (i.e. `foo`) cannot constrain
+// an RPITIT from another function (`bar`).
+
+trait Trait {
+    fn foo();
+
+    fn bar() -> impl Sized;
+}
+
+impl Trait for () {
+    fn foo() {
+        let _: String = Self::bar();
+        //~^ ERROR mismatched types
+    }
+
+    fn bar() -> impl Sized {
+        loop {}
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/in-trait/sibling-function-constraint.stderr b/tests/ui/impl-trait/in-trait/sibling-function-constraint.stderr
new file mode 100644
index 000000000..729963a81
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/sibling-function-constraint.stderr
@@ -0,0 +1,17 @@
+error[E0308]: mismatched types
+  --> $DIR/sibling-function-constraint.rs:12:25
+   |
+LL |         let _: String = Self::bar();
+   |                ------   ^^^^^^^^^^^ expected `String`, found opaque type
+   |                |
+   |                expected due to this
+...
+LL |     fn bar() -> impl Sized {
+   |                 ---------- the found opaque type
+   |
+   = note:   expected struct `String`
+           found opaque type `impl Sized`
+
+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/signature-mismatch.rs b/tests/ui/impl-trait/in-trait/signature-mismatch.rs
index 685c0f06e..d85ee5fc7 100644
--- a/tests/ui/impl-trait/in-trait/signature-mismatch.rs
+++ b/tests/ui/impl-trait/in-trait/signature-mismatch.rs
@@ -2,7 +2,7 @@
 // revisions: success failure
 //[success] check-pass
 
-#![feature(return_position_impl_trait_in_trait, lint_reasons)]
+#![feature(lint_reasons)]
 
 use std::future::Future;
 
diff --git a/tests/ui/impl-trait/in-trait/specialization-broken.rs b/tests/ui/impl-trait/in-trait/specialization-broken.rs
index 2fcffdf3f..a06cd814f 100644
--- a/tests/ui/impl-trait/in-trait/specialization-broken.rs
+++ b/tests/ui/impl-trait/in-trait/specialization-broken.rs
@@ -2,7 +2,6 @@
 // But we fixed an ICE anyways.
 
 #![feature(specialization)]
-#![feature(return_position_impl_trait_in_trait)]
 #![allow(incomplete_features)]
 
 trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/specialization-broken.stderr b/tests/ui/impl-trait/in-trait/specialization-broken.stderr
index dc621d6b8..25c0adedd 100644
--- a/tests/ui/impl-trait/in-trait/specialization-broken.stderr
+++ b/tests/ui/impl-trait/in-trait/specialization-broken.stderr
@@ -1,8 +1,8 @@
 error[E0053]: method `bar` has an incompatible type for trait
-  --> $DIR/specialization-broken.rs:16:22
+  --> $DIR/specialization-broken.rs:15:22
    |
 LL | default impl<U> Foo for U
-   |              - this type parameter
+   |              - found this type parameter
 ...
 LL |     fn bar(&self) -> U {
    |                      ^
@@ -11,7 +11,7 @@ LL |     fn bar(&self) -> U {
    |                      help: change the output type to match the trait: `impl Sized`
    |
 note: type in trait
-  --> $DIR/specialization-broken.rs:9:22
+  --> $DIR/specialization-broken.rs:8:22
    |
 LL |     fn bar(&self) -> impl Sized;
    |                      ^^^^^^^^^^
@@ -19,12 +19,12 @@ LL |     fn bar(&self) -> impl Sized;
               found signature `fn(&U) -> U`
 
 error: method with return-position `impl Trait` in trait cannot be specialized
-  --> $DIR/specialization-broken.rs:16:5
+  --> $DIR/specialization-broken.rs:15:5
    |
 LL |     fn bar(&self) -> U {
    |     ^^^^^^^^^^^^^^^^^^
    |
-   = note: specialization behaves in inconsistent and surprising ways with `#![feature(return_position_impl_trait_in_trait)]`, and for now is disallowed
+   = note: specialization behaves in inconsistent and surprising ways with return position `impl Trait` in traits, and for now is disallowed
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/impl-trait/in-trait/specialization-substs-remap.rs b/tests/ui/impl-trait/in-trait/specialization-substs-remap.rs
index 41fc28588..053866327 100644
--- a/tests/ui/impl-trait/in-trait/specialization-substs-remap.rs
+++ b/tests/ui/impl-trait/in-trait/specialization-substs-remap.rs
@@ -1,7 +1,7 @@
 // check-pass
 
 #![feature(specialization)]
-#![feature(return_position_impl_trait_in_trait, lint_reasons)]
+#![feature(lint_reasons)]
 #![allow(incomplete_features)]
 
 pub trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/success.rs b/tests/ui/impl-trait/in-trait/success.rs
index 7d415ea17..eb2349feb 100644
--- a/tests/ui/impl-trait/in-trait/success.rs
+++ b/tests/ui/impl-trait/in-trait/success.rs
@@ -1,6 +1,6 @@
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait, lint_reasons)]
+#![feature(lint_reasons)]
 #![allow(incomplete_features)]
 
 use std::fmt::Display;
diff --git a/tests/ui/impl-trait/in-trait/suggest-missing-item.fixed b/tests/ui/impl-trait/in-trait/suggest-missing-item.fixed
index d9f775a6c..8dc8e045d 100644
--- a/tests/ui/impl-trait/in-trait/suggest-missing-item.fixed
+++ b/tests/ui/impl-trait/in-trait/suggest-missing-item.fixed
@@ -1,15 +1,16 @@
 // edition:2021
 // run-rustfix
 
-#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
-
 trait Trait {
+    #[allow(async_fn_in_trait)]
     async fn foo();
 
+    #[allow(async_fn_in_trait)]
     async fn bar() -> i32;
 
     fn test(&self) -> impl Sized + '_;
 
+    #[allow(async_fn_in_trait)]
     async fn baz(&self) -> &i32;
 }
 
diff --git a/tests/ui/impl-trait/in-trait/suggest-missing-item.rs b/tests/ui/impl-trait/in-trait/suggest-missing-item.rs
index 26979b514..30b04d87b 100644
--- a/tests/ui/impl-trait/in-trait/suggest-missing-item.rs
+++ b/tests/ui/impl-trait/in-trait/suggest-missing-item.rs
@@ -1,15 +1,16 @@
 // edition:2021
 // run-rustfix
 
-#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
-
 trait Trait {
+    #[allow(async_fn_in_trait)]
     async fn foo();
 
+    #[allow(async_fn_in_trait)]
     async fn bar() -> i32;
 
     fn test(&self) -> impl Sized + '_;
 
+    #[allow(async_fn_in_trait)]
     async fn baz(&self) -> &i32;
 }
 
diff --git a/tests/ui/impl-trait/in-trait/suggest-missing-item.stderr b/tests/ui/impl-trait/in-trait/suggest-missing-item.stderr
index 44f98896e..cec94e39a 100644
--- a/tests/ui/impl-trait/in-trait/suggest-missing-item.stderr
+++ b/tests/ui/impl-trait/in-trait/suggest-missing-item.stderr
@@ -1,15 +1,15 @@
 error[E0046]: not all trait items implemented, missing: `foo`, `bar`, `test`, `baz`
-  --> $DIR/suggest-missing-item.rs:18:1
+  --> $DIR/suggest-missing-item.rs:19:1
    |
 LL |     async fn foo();
    |     --------------- `foo` from trait
-LL |
+...
 LL |     async fn bar() -> i32;
    |     ---------------------- `bar` from trait
 LL |
 LL |     fn test(&self) -> impl Sized + '_;
    |     ---------------------------------- `test` from trait
-LL |
+...
 LL |     async fn baz(&self) -> &i32;
    |     ---------------------------- `baz` from trait
 ...
diff --git a/tests/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs b/tests/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
index 0bbe50ea6..d9fac0238 100644
--- a/tests/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
+++ b/tests/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
@@ -1,6 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-#![allow(incomplete_features)]
-
 struct S;
 
 trait Foo {
diff --git a/tests/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr b/tests/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
index 8ff54cad9..2836e9c78 100644
--- a/tests/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
+++ b/tests/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
@@ -1,5 +1,5 @@
 error[E0049]: method `bar` has 0 type parameters but its trait declaration has 1 type parameter
-  --> $DIR/trait-more-generics-than-impl.rs:11:11
+  --> $DIR/trait-more-generics-than-impl.rs:8:11
    |
 LL |     fn bar<T>() -> impl Sized;
    |            - expected 1 type parameter
diff --git a/tests/ui/impl-trait/in-trait/unconstrained-lt.rs b/tests/ui/impl-trait/in-trait/unconstrained-lt.rs
index 07c8606f9..ff3753de5 100644
--- a/tests/ui/impl-trait/in-trait/unconstrained-lt.rs
+++ b/tests/ui/impl-trait/in-trait/unconstrained-lt.rs
@@ -1,5 +1,3 @@
-#![feature(return_position_impl_trait_in_trait)]
-
 trait Foo {
     fn test() -> impl Sized;
 }
diff --git a/tests/ui/impl-trait/in-trait/unconstrained-lt.stderr b/tests/ui/impl-trait/in-trait/unconstrained-lt.stderr
index cfce35567..61a0f8454 100644
--- a/tests/ui/impl-trait/in-trait/unconstrained-lt.stderr
+++ b/tests/ui/impl-trait/in-trait/unconstrained-lt.stderr
@@ -1,5 +1,5 @@
 error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
-  --> $DIR/unconstrained-lt.rs:7:6
+  --> $DIR/unconstrained-lt.rs:5:6
    |
 LL | impl<'a, T> Foo for T {
    |      ^^ unconstrained lifetime parameter
diff --git a/tests/ui/impl-trait/in-trait/variance.rs b/tests/ui/impl-trait/in-trait/variance.rs
index f8e4ab88c..65565dcc2 100644
--- a/tests/ui/impl-trait/in-trait/variance.rs
+++ b/tests/ui/impl-trait/in-trait/variance.rs
@@ -1,4 +1,4 @@
-#![feature(rustc_attrs, return_position_impl_trait_in_trait)]
+#![feature(rustc_attrs)]
 #![allow(internal_features)]
 #![rustc_variance_of_opaques]
 
diff --git a/tests/ui/impl-trait/in-trait/variances-of-gat.rs b/tests/ui/impl-trait/in-trait/variances-of-gat.rs
index 0d19e1ff4..aabb6f830 100644
--- a/tests/ui/impl-trait/in-trait/variances-of-gat.rs
+++ b/tests/ui/impl-trait/in-trait/variances-of-gat.rs
@@ -1,6 +1,5 @@
 // check-pass
 
-#![feature(return_position_impl_trait_in_trait)]
 
 trait Foo {}
 
diff --git a/tests/ui/impl-trait/in-trait/wf-bounds.rs b/tests/ui/impl-trait/in-trait/wf-bounds.rs
index ee873f94b..f1e372b19 100644
--- a/tests/ui/impl-trait/in-trait/wf-bounds.rs
+++ b/tests/ui/impl-trait/in-trait/wf-bounds.rs
@@ -1,6 +1,5 @@
 // issue #101663
 
-#![feature(return_position_impl_trait_in_trait)]
 #![allow(incomplete_features)]
 
 use std::fmt::Display;
diff --git a/tests/ui/impl-trait/in-trait/wf-bounds.stderr b/tests/ui/impl-trait/in-trait/wf-bounds.stderr
index 4d60b1330..c20df9b40 100644
--- a/tests/ui/impl-trait/in-trait/wf-bounds.stderr
+++ b/tests/ui/impl-trait/in-trait/wf-bounds.stderr
@@ -1,5 +1,5 @@
 error[E0277]: the size for values of type `[u8]` cannot be known at compilation time
-  --> $DIR/wf-bounds.rs:15:22
+  --> $DIR/wf-bounds.rs:14:22
    |
 LL |     fn nya() -> impl Wf<Vec<[u8]>>;
    |                      ^^^^^^^^^^^^^ doesn't have a size known at compile-time
@@ -9,14 +9,14 @@ note: required by a bound in `Vec`
   --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
 
 error[E0277]: the size for values of type `[u8]` cannot be known at compilation time
-  --> $DIR/wf-bounds.rs:18:23
+  --> $DIR/wf-bounds.rs:17:23
    |
 LL |     fn nya2() -> impl Wf<[u8]>;
    |                       ^^^^^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `Sized` is not implemented for `[u8]`
 note: required by a bound in `Wf`
-  --> $DIR/wf-bounds.rs:8:10
+  --> $DIR/wf-bounds.rs:7:10
    |
 LL | trait Wf<T> {
    |          ^ required by this bound in `Wf`
@@ -26,7 +26,7 @@ LL | trait Wf<T: ?Sized> {
    |           ++++++++
 
 error[E0277]: the size for values of type `[u8]` cannot be known at compilation time
-  --> $DIR/wf-bounds.rs:21:44
+  --> $DIR/wf-bounds.rs:20:44
    |
 LL |     fn nya3() -> impl Wf<(), Output = impl Wf<Vec<[u8]>>>;
    |                                            ^^^^^^^^^^^^^ doesn't have a size known at compile-time
@@ -36,14 +36,14 @@ note: required by a bound in `Vec`
   --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
 
 error[E0277]: `T` doesn't implement `std::fmt::Display`
-  --> $DIR/wf-bounds.rs:24:26
+  --> $DIR/wf-bounds.rs:23:26
    |
 LL |     fn nya4<T>() -> impl Wf<NeedsDisplay<T>>;
    |                          ^^^^^^^^^^^^^^^^^^^ `T` cannot be formatted with the default formatter
    |
    = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
 note: required by a bound in `NeedsDisplay`
-  --> $DIR/wf-bounds.rs:12:24
+  --> $DIR/wf-bounds.rs:11:24
    |
 LL | struct NeedsDisplay<T: Display>(T);
    |                        ^^^^^^^ required by this bound in `NeedsDisplay`
diff --git a/tests/ui/impl-trait/in-trait/where-clause.rs b/tests/ui/impl-trait/in-trait/where-clause.rs
index 87bac519c..f7f4980b7 100644
--- a/tests/ui/impl-trait/in-trait/where-clause.rs
+++ b/tests/ui/impl-trait/in-trait/where-clause.rs
@@ -1,7 +1,6 @@
 // check-pass
 // edition: 2021
 
-#![feature(return_position_impl_trait_in_trait)]
 #![allow(incomplete_features)]
 
 use std::fmt::Debug;