c-variadic: test that we use equality up to free lifetimes tracking issue: https://github.com/rust-lang/rust/issues/44930 Test that we use equality up to free lifetimes, and correctly consider `for<'a> &'a` to be different from `&'static`. I'm not sure if I'm missing any type subtleties here? Because it seems like the current implementation already has the behavior that we want. (and that `==` on `Ty` has this behavior). Also see https://github.com/rust-lang/rust/pull/155697#issuecomment-4666457403 and https://github.com/rust-lang/rust/pull/155697#issuecomment-4730822126. cc @theemathas r? RalfJung,lcnr