trait Trait<'a> { type Assoc; } fn foo<T: for<'a> Trait<'a>>() -> for<'a> fn(<T as Trait<'a>>::Assoc) { todo!() } fn bar<T: for<'a> Trait<'a>>() { let _: for<'a> fn(<_ as Trait<'a>>::Assoc) = foo::<T>(); }

This changed from an ICE on stable to compiling on beta and nightly: https://godbolt.org/z/E45bfa1d1

this shouldn't happen unintentionally and afaik we haven't added a test for this behavior either.

It would be very good to figure out which PR is responsible for this change.