Rollup of 7 pull requests#71230

Merged

bors merged 23 commits intorust-lang:masterfrom

Dylan-DPC-zz:rollup-rofigbv

Apr 17, 2020

Commits on Apr 8, 2020

Added FuseIteratorImpl, FustDoubleEndedIteratorImpl and FuseExactSizeIteratorImpl to avoid exposing default functions outside of the current crate.
rakshith-ravi
committed

Commits on Apr 10, 2020

Added comments.
rakshith-ravi
committed

Commits on Apr 13, 2020

Add proper explanation of error code E0657
Polkaverse
committed

Commits on Apr 15, 2020

Commits on Apr 16, 2020

Commits on Apr 17, 2020