Rollup of 6 pull requests
Successful merges:
- #68770 (BTreeMap/BTreeSet: implement drain_filter )
- #70081 (add `unused_braces` lint)
- #70556 (parse_and_disallow_postfix_after_cast: account for `ExprKind::Err`.)
- #70605 (Add missing -lmsvcrt on mingw after -lpthread)
- #70630 (Update books.)
- #70632 (expand vec![] to Vec::new())
Failed merges:
r? @ghost