SQ -> Fix recognition of several typing special forms, including: Optional, Union, Callable

Author: davidfstr

mypy/semanal.py

@@ -7845,7 +7845,7 @@ def try_parse_as_type_expression(self, maybe_type_expr: Expression) -> None:
             if isinstance(maybe_type_expr.base, NameExpr):
                 if isinstance(
                     maybe_type_expr.base.node, Var
-                ) and not self.var_is_typing_special_form(maybe_type_expr.base):
+                ) and not self.var_is_typing_special_form(maybe_type_expr.base.node):
                     # Leftmost part of IndexExpr refers to a Var. Not a valid type.
                     maybe_type_expr.as_type = None
                     return