Rollup of 5 pull requests
Successful merges:
- #102143 (Recover from struct nested in struct)
- #102178 (bootstrap: the backtrace feature is stable, no need to allow it any more)
- #102197 (Stabilize const `BTree{Map,Set}::new`)
- #102267 (Don't set RUSTC in the bootstrap build script)
- #102270 (Remove benches from `rustc_middle`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup