Rollup merge of #28194 - steveklabnik:add_fixme, r=alexcrichton
Rollup merge of #28194 - steveklabnik:add_fixme, r=alexcrichton

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