Avoid checking types of Callable when both type objects are pointing to the same reference. This is a small check which would speed up cases drastically such as recursive generics with unions, since the type is equal but Pytype holds the expanded union type and attempts to go in deep to figure out each individual type matches.

PiperOrigin-RevId: 700376520

Author: h-joo

pytype/matcher.py

@@ -1550,6 +1550,11 @@ def _match_callable_args_against_callable(
   ):
     # TODO(mdemello): Unify with _match_signature_args_against_callable()
     param_match = self._get_param_matcher(other_type)
+    # Checking type against the same type should happen quite often. This check
+    # helps avoiding near-infinite type expansion for recursive generic types
+    # which are identical.
+    if left is other_type:
+      return subst
     for i in range(left.num_args):
       left_arg = left.formal_type_parameters[i]
       right_arg = other_type.formal_type_parameters[i]