Rollup merge of #132612 - compiler-errors:async-trait-bounds, r=lcnr

Gate async fn trait bound modifier on `async_trait_bounds`

This PR moves `async Fn()` trait bounds into a new feature gate: `feature(async_trait_bounds)`. The general vibe is that we will most likely stabilize the `feature(async_closure)` *without* the `async Fn()` trait bound modifier, so we need to gate that separately.

We're trying to work on the general vision of `async` trait bound modifier general in: https://github.com/rust-lang/rfcs/pull/3710, however that RFC still needs more time for consensus to converge, and we've decided that the value that users get from calling the bound `async Fn()` is *not really* worth blocking landing async closures in general.

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/codegen/async-closure-debug.rs b/tests/codegen/async-closure-debug.rs
index 9cb1e623295..644df169a36 100644
--- a/tests/codegen/async-closure-debug.rs
+++ b/tests/codegen/async-closure-debug.rs
@@ -9,7 +9,7 @@
 
 #![feature(async_closure)]
 
-fn async_closure_test(upvar: &str) -> impl async Fn() + '_ {
+fn async_closure_test(upvar: &str) -> impl AsyncFn() + '_ {
     async move || {
         let hello = String::from("hello");
         println!("{hello}, {upvar}");