Tweak feature error, add test

2 files changed, 24 insertions, 0 deletions

diff --git a/src/test/ui/impl-trait/in-trait/reveal.rs b/src/test/ui/impl-trait/in-trait/reveal.rs
new file mode 100644
index 00000000000..d6ede1cc495
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/reveal.rs
@@ -0,0 +1,18 @@
+// check-pass
+
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+trait Foo {
+    fn f() -> Box<impl Sized>;
+}
+
+impl Foo for () {
+    fn f() -> Box<String> {
+        Box::new(String::new())
+    }
+}
+
+fn main() {
+    let x: Box<String> = <() as Foo>::f();
+}
diff --git a/src/test/ui/impl-trait/where-allowed.stderr b/src/test/ui/impl-trait/where-allowed.stderr
index 58a2f79efb4..9b346387d61 100644
--- a/src/test/ui/impl-trait/where-allowed.stderr
+++ b/src/test/ui/impl-trait/where-allowed.stderr
@@ -162,12 +162,18 @@ error[E0562]: `impl Trait` only allowed in function and inherent method return t
    |
 LL |     fn in_return() -> impl Debug;
    |                       ^^^^^^^^^^
+   |
+   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
+   = help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
 
 error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `impl` method return
   --> $DIR/where-allowed.rs:125:34
    |
 LL |     fn in_trait_impl_return() -> impl Debug { () }
    |                                  ^^^^^^^^^^
+   |
+   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
+   = help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
 
 error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `extern fn` param
   --> $DIR/where-allowed.rs:138:33