Auto merge of #28825 - iwillspeak:master, r=alexcrichton
Auto merge of #28825 - iwillspeak:master, r=alexcrichton

`--explain` support for E0163 and E0164.

Part of rust-lang/rust#24407

graydon/rust,GBGamer/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust,aidancully/rust