Rollup of 14 pull requests#80999

Closed

JohnTitor wants to merge 31 commits intorust-lang:masterfrom

JohnTitor:rollup-z3cxrfc

Commits on Dec 18, 2020

Recommend panic::resume_unwind instead of panicking.
frewsxcv
committed

Commits on Dec 20, 2020

Add a `std::io::read_to_string` function
camelid
committed

Commits on Dec 30, 2020

Commits on Jan 9, 2021

Remove unreachable panics from VecDeque
bugadani
committed

Commits on Jan 12, 2021

Add docs on performance
camelid
committed

Commits on Jan 13, 2021

Commits on Jan 14, 2021