Rollup of 8 pull requests
Successful merges:
- #69528 (Add undo_leak to reset RefCell borrow state)
- #69589 (ast: `Mac`/`Macro` -> `MacCall`)
- #69661 (Implement From<&mut str> for String)
- #69988 (rustc_metadata: Remove `rmeta::MacroDef`)
- #70006 (resolve: Fix two issues in fresh binding disambiguation)
- #70011 (def_collector: Fully visit async functions)
- #70013 (Return feature gate as a `Symbol` )
- #70018 (Fix "since" field for `Once::is_complete`'s `#[stable]` attribute)
Failed merges:
r? @ghost