Start using #[diagnostic::do_not_recommend] in the standard library

This commit starts using `#[diagnostic::do_not_recommend]` in the
standard library to improve some error messages. In this case we just
hide a certain nightly only impl as suggested in #121521

library/core/src/lib.rs

@@ -165,6 +165,7 @@
 #![feature(const_unsafecell_get_mut)]
 #![feature(const_waker)]
 #![feature(coverage_attribute)]
+#![feature(do_not_recommend)]
 #![feature(duration_consts_float)]
 #![feature(internal_impls_macro)]
 #![feature(ip)]

library/core/src/option.rs

@@ -2507,6 +2507,7 @@ impl<T> ops::FromResidual for Option<T> {
     }
 }
 
+#[diagnostic::do_not_recommend]
 #[unstable(feature = "try_trait_v2_yeet", issue = "96374")]
 impl<T> ops::FromResidual<ops::Yeet<()>> for Option<T> {
     #[inline]

library/core/src/result.rs

@@ -1990,7 +1990,7 @@ impl<T, E, F: From<E>> ops::FromResidual<Result<convert::Infallible, E>> for Res
         }
     }
 }
-
+#[diagnostic::do_not_recommend]
 #[unstable(feature = "try_trait_v2_yeet", issue = "96374")]
 impl<T, E, F: From<E>> ops::FromResidual<ops::Yeet<E>> for Result<T, F> {
     #[inline]

tests/ui/try-trait/bad-interconversion.stderr

@@ -23,9 +23,7 @@ LL |     Some(3)?;
    |            ^ use `.ok_or(...)?` to provide an error compatible with `Result<u64, String>`
    |
    = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `Result<u64, String>`
-   = help: the following other types implement trait `FromResidual<R>`:
-             `Result<T, F>` implements `FromResidual<Result<Infallible, E>>`
-             `Result<T, F>` implements `FromResidual<Yeet<E>>`
+   = help: the trait `FromResidual<Result<Infallible, E>>` is implemented for `Result<T, F>`
 
 error[E0277]: the `?` operator can only be used on `Result`s in a function that returns `Result`
   --> $DIR/bad-interconversion.rs:17:31
@@ -36,9 +34,7 @@ LL |     Ok(ControlFlow::Break(123)?)
    |                               ^ this `?` produces `ControlFlow<{integer}, Infallible>`, which is incompatible with `Result<u64, String>`
    |
    = help: the trait `FromResidual<ControlFlow<{integer}, Infallible>>` is not implemented for `Result<u64, String>`
-   = help: the following other types implement trait `FromResidual<R>`:
-             `Result<T, F>` implements `FromResidual<Result<Infallible, E>>`
-             `Result<T, F>` implements `FromResidual<Yeet<E>>`
+   = help: the trait `FromResidual<Result<Infallible, E>>` is implemented for `Result<T, F>`
 
 error[E0277]: the `?` operator can only be used on `Option`s, not `Result`s, in a function that returns `Option`
   --> $DIR/bad-interconversion.rs:22:22
@@ -49,9 +45,7 @@ LL |     Some(Err("hello")?)
    |                      ^ use `.ok()?` if you want to discard the `Result<Infallible, &str>` error information
    |
    = help: the trait `FromResidual<Result<Infallible, &str>>` is not implemented for `Option<u16>`
-   = help: the following other types implement trait `FromResidual<R>`:
-             `Option<T>` implements `FromResidual<Yeet<()>>`
-             `Option<T>` implements `FromResidual`
+   = help: the trait `FromResidual` is implemented for `Option<T>`
 
 error[E0277]: the `?` operator can only be used on `Option`s in a function that returns `Option`
   --> $DIR/bad-interconversion.rs:27:33
@@ -62,9 +56,7 @@ LL |     Some(ControlFlow::Break(123)?)
    |                                 ^ this `?` produces `ControlFlow<{integer}, Infallible>`, which is incompatible with `Option<u64>`
    |
    = help: the trait `FromResidual<ControlFlow<{integer}, Infallible>>` is not implemented for `Option<u64>`
-   = help: the following other types implement trait `FromResidual<R>`:
-             `Option<T>` implements `FromResidual<Yeet<()>>`
-             `Option<T>` implements `FromResidual`
+   = help: the trait `FromResidual` is implemented for `Option<T>`
 
 error[E0277]: the `?` operator can only be used on `ControlFlow`s in a function that returns `ControlFlow`
   --> $DIR/bad-interconversion.rs:32:39

tests/ui/try-trait/option-to-result.stderr

@@ -8,9 +8,7 @@ LL |     a?;
    |      ^ use `.ok_or(...)?` to provide an error compatible with `Result<(), ()>`
    |
    = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `Result<(), ()>`
-   = help: the following other types implement trait `FromResidual<R>`:
-             `Result<T, F>` implements `FromResidual<Result<Infallible, E>>`
-             `Result<T, F>` implements `FromResidual<Yeet<E>>`
+   = help: the trait `FromResidual<Result<Infallible, E>>` is implemented for `Result<T, F>`
 
 error[E0277]: the `?` operator can only be used on `Option`s, not `Result`s, in a function that returns `Option`
   --> $DIR/option-to-result.rs:11:6
@@ -22,9 +20,7 @@ LL |     a?;
    |      ^ use `.ok()?` if you want to discard the `Result<Infallible, i32>` error information
    |
    = help: the trait `FromResidual<Result<Infallible, i32>>` is not implemented for `Option<i32>`
-   = help: the following other types implement trait `FromResidual<R>`:
-             `Option<T>` implements `FromResidual<Yeet<()>>`
-             `Option<T>` implements `FromResidual`
+   = help: the trait `FromResidual` is implemented for `Option<T>`
 
 error: aborting due to 2 previous errors
 

tests/ui/try-trait/try-on-option.stderr

@@ -8,9 +8,7 @@ LL |     x?;
    |      ^ use `.ok_or(...)?` to provide an error compatible with `Result<u32, ()>`
    |
    = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `Result<u32, ()>`
-   = help: the following other types implement trait `FromResidual<R>`:
-             `Result<T, F>` implements `FromResidual<Result<Infallible, E>>`
-             `Result<T, F>` implements `FromResidual<Yeet<E>>`
+   = help: the trait `FromResidual<Result<Infallible, E>>` is implemented for `Result<T, F>`
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> $DIR/try-on-option.rs:11:6