Rollup of 14 pull requests#79920

Closed

Dylan-DPC-zz wants to merge 38 commits intorust-lang:masterfrom

Dylan-DPC-zz:rollup-4muy87v

Commits on Sep 21, 2020

Edit documentation for `std::{f32,f64}::mul_add`.
fu5ha
committed

Commits on Oct 13, 2020

generalize warning
fu5ha
committed

Commits on Dec 3, 2020

Make the kernel_copy tests more robust/concurrent.
vext01
committed

Commits on Dec 4, 2020

Refine E0212 error message
sasurau4
committed
Add long explanation for E0212

sasurau4
and
Joshua Nelson
committed
Update some associated-types ui test suites
sasurau4
committed

Commits on Dec 8, 2020

Commits on Dec 9, 2020

Commits on Dec 10, 2020