Fix substitution of Self type in functions

trans/transpiler/phases/typing/expr.py

@@ -105,7 +105,7 @@ class ScoperExprVisitor(ScoperVisitor):
     def visit_Call(self, node: ast.Call) -> BaseType:
         ftype = self.visit(node.func)
         if ftype.typevars:
-            ftype = ftype.gen_sub(None, {v.name: TypeVariable(v.name) for v in ftype.typevars})
+            ftype = ftype.gen_sub(ftype, {v.name: TypeVariable(v.name) for v in ftype.typevars})
         rtype = self.visit_function_call(ftype, [self.visit(arg) for arg in node.args])
         actual = rtype
         node.is_await = False
@@ -174,6 +174,7 @@ class ScoperExprVisitor(ScoperVisitor):
                 attr.python_func_used = True
             return attr
         if meth := ltype.methods.get(name):
+            meth = meth.gen_sub(ltype, {})
             if bound:
                 return meth.remove_self()
             else:

trans/transpiler/phases/typing/types.py

@@ -241,9 +241,10 @@ class TypeOperator(BaseType, ABC):
             return me
         if len(self.args) == 0:
             return self
+        assert all(x is not None for x in self.args)
         res = object.__new__(self.__class__)  # todo: ugly... should make a clone()
         cache[self] = res
-        if isinstance(this, TypeOperator):
+        if isinstance(this, TypeOperator) and not isinstance(this, FunctionType):
             vardict = dict(zip(typevars.keys(), this.args))
         else:
             vardict = typevars