I haven’t thought too deeply about how much of a problem this is, but a potential remaining concern with the API you’re proposing is that a type like
struct Foo(&'static str);
could be changed into
struct Foo<T = &'static str>(T);
with the intention of this being a non-breaking change, however this changes the behavior of
intrinsics::all_types_with_this_id_are_static::<Foo>()
from true to false, and thus breaks use-cases of type_id.same_as::<Foo>().