Improve some pointer-related documentation#62822

Merged

bors merged 8 commits intorust-lang:masterfrom RalfJung:pointers

Jul 26, 2019

Commits on Jul 20, 2019

warn that raw pointers must be aligned when used, and that writes cause drop
RalfJung
committed
references must be aligned; also move up the warning that fn ptrs must be non-NULL
RalfJung
committed

Commits on Jul 21, 2019

Commits on Jul 22, 2019

Commits on Jul 23, 2019