Rollup of 8 pull requests Successful merges: - #120005 (Update Readme) - #120045 (Un-hide `iter::repeat_n`) - #120128 (Make stable_mir::with_tables sound) - #120145 (fix: Drop guard was deallocating with the incorrect size) - #120158 (`rustc_mir_dataflow`: Restore removed exports) - #120167 (Capture the rationale for `-Zallow-features=` in bootstrap.py) - #120174 (Warn users about limited review for tier 2 and 3 code) - #120180 (Document some alternatives to `Vec::split_off`) Failed merges: - #120171 (Fix assume and assert in jump threading) r? `@ghost` `@rustbot` modify labels: rollup