Rollup of 8 pull requests#77712

Closed

Dylan-DPC-zz wants to merge 17 commits intorust-lang:masterfrom

Dylan-DPC-zz:rollup-5k2bx6c

Commits on Oct 3, 2020

BTreeMap: comment why drain_filter's size_hint is somewhat pessimistictid
ssomers
committed

Commits on Oct 7, 2020

Commits on Oct 8, 2020