pub fn compatible(t: TyId, u: TyId, tys: &Types) -> boolExpand description
t is usable where u is expected.
T3.6b: deliberately no t == u fast path, tempting as interning makes
one. compatible is not reflexive — Actor/ActorSum are sealed boundary
values that fall through to the false arm below even against themselves
(they are matched, never assigned), so short-circuiting on id equality
would silently make them assignable.