Auto merge of #65053 - Centril:rollup-nwp0wgf, r=Centril

Rollup of 5 pull requests

Successful merges:

 - #64690 (proc_macro API: Expose `macro_rules` hygiene)
 - #64749 (Fix most remaining Polonius test differences)
 - #64938 (Avoid ICE on ReFree region on where clause)
 - #64999 (extract expected return type for async fn generators)
 - #65037 (`#[track_caller]` feature gate (RFC 2091))

Failed merges:

r? @ghost

Author: bors

src/doc/unstable-book/src/language-features/track-caller.md

@@ -0,0 +1,5 @@
+# `track_caller`
+
+The tracking issue for this feature is: [#47809](https://github.com/rust-lang/rust/issues/47809).
+
+------------------------

src/libproc_macro/bridge/mod.rs

@@ -148,6 +148,7 @@ macro_rules! with_api {
                 fn debug($self: $S::Span) -> String;
                 fn def_site() -> $S::Span;
                 fn call_site() -> $S::Span;
+                fn mixed_site() -> $S::Span;
                 fn source_file($self: $S::Span) -> $S::SourceFile;
                 fn parent($self: $S::Span) -> Option<$S::Span>;
                 fn source($self: $S::Span) -> $S::Span;