Rollup merge of #72711 - lcnr:fixme-heyho, r=jonas-schievink
Rollup merge of #72711 - lcnr:fixme-heyho, r=jonas-schievink

remove redundant `mk_const`

Taken from #72675 as this is fairly unrelated and that PR is more difficult than I imagined,
so it may take some time until it lands.

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