error: implementation of `FnOnce` is not general enough --> $DIR/issue-79187.rs:5:5 | LL | thing(f); | ^^^^^ implementation of `FnOnce` is not general enough | = note: closure with signature `fn(&'2 u32)` must implement `FnOnce<(&'1 u32,)>`, for any lifetime `'1`... = note: ...but it actually implements `FnOnce<(&'2 u32,)>`, for some specific lifetime `'2` error: aborting due to previous error