Auto merge of rust-lang#64946 - Centril:rollup-66mj5o0, r=Centril

Rollup of 10 pull requests

Successful merges:

 - rust-lang#63674 (syntax: Support modern attribute syntax in the `meta` matcher)
 - rust-lang#63931 (Stabilize macros in some more positions)
 - rust-lang#64887 (syntax: recover trailing `|` in or-patterns)
 - rust-lang#64895 (async/await: improve not-send errors)
 - rust-lang#64896 (Remove legacy grammar)
 - rust-lang#64907 (A small amount of tidying-up factored out from PR rust-lang#64648)
 - rust-lang#64928 (Add tests for some issues)
 - rust-lang#64930 (Silence unreachable code lint from await desugaring)
 - rust-lang#64935 (Improve code clarity)
 - rust-lang#64937 (Deduplicate closure type errors)

Failed merges:

r? @ghost

Author: bors