Rollup merge of #75449 - RalfJung:const-prop-test, r=wesleywiser
Rollup merge of #75449 - RalfJung:const-prop-test, r=wesleywiser

add regression test for #74739 (mir const-prop bug)

Fixes https://github.com/rust-lang/rust/issues/74739

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