Rollup of 6 pull requests#68854

Closed

Centril wants to merge 15 commits intorust-lang:masterfrom

Centril:rollup-cofz94u

Commits on Feb 2, 2020

Strip unnecessary subexpression
ForNeVeR
authored

Commits on Feb 3, 2020

Commits on Feb 4, 2020

Clean up E0264, E0267 and E0268 explanations
GuillaumeGomez
committed

Commits on Feb 5, 2020