Unification or pattern matching for matching `UnionAll` types against each other

I think that I already tried that above. If you know the answer, can you tell me how I can get e.g. (:type_arg_1=Int64) out of (Ptr, Ptr{Int64})? You mentioned, “[type variables] may be made available as a local variable in a method body inside”. I would like to get those bounds, given some types and a method signature.