Rollup of 10 pull requests#84729

Merged

bors merged 23 commits intorust-lang:masterfrom

jackh726:rollup-dnm8kg5

Apr 30, 2021

Commits on Apr 22, 2021

Use flex more consistently.
Tor Hovland
committed

Commits on Apr 26, 2021

Point out that behavior might be switched on 2015 and 2018 editions too one day
est31
committed

Commits on Apr 27, 2021

Add a paragraph with possible alternatives on older editions
est31
committed

Commits on Apr 28, 2021

Commits on Apr 29, 2021