Fix bug with multiple generic inheritence

Previously if the same generic base class appeared multiple times in a
classes inheritence graph msgspec would error when trying to analyze the
class. This PR fixes the bug and adds a test for the behavior.

msgspec/_utils.py

@@ -74,13 +74,12 @@ def inner(c, scope):
  new_scope = {}
  else:
  cls = getattr(c, "__origin__", None)
- if cls in (None, object, typing.Generic):
+ if cls in (None, object, typing.Generic) or cls in mapping:
  return
- if cls not in mapping:
- params = cls.__parameters__
- args = tuple(_apply_params(a, scope) for a in c.__args__)
- assert len(params) == len(args)
- mapping[cls] = new_scope = dict(zip(params, args))
+ params = cls.__parameters__
+ args = tuple(_apply_params(a, scope) for a in c.__args__)
+ assert len(params) == len(args)
+ mapping[cls] = new_scope = dict(zip(params, args))
 
  if issubclass(cls, typing.Generic):
  bases = getattr(cls, "__orig_bases__", cls.__bases__)

tests/test_utils.py

@@ -181,3 +181,12 @@ class Sub3(Sub[List[T]]):
  "a": List[List[int]],
  "b": List[int],
  }
+
+ def test_generic_sub11(self):
+ class Sub(Base[int]):
+ y: float
+
+ class Sub2(Sub, Base[int]):
+ z: str
+
+ assert get_class_annotations(Sub2) == {"x": int, "y": float, "z": str}