Infer user-defined enum classes by checking if the class is a subtype of enum.Enum (#2277) (#2298)

(cherry picked from commit c5352d5)
Co-authored-by: Jacob Walls <jacobtylerwalls@gmail.com>

Co-authored-by: Mark Byrne <31762852+mbyrnepr2@users.noreply.github.com>

Author: jacobtylerwalls

ChangeLog

@@ -20,6 +20,10 @@ Release date: TBA
 
   Closes pylint-dev/pylint#8802
 
+* Infer user-defined enum classes by checking if the class is a subtype of ``enum.Enum``.
+
+  Closes pylint-dev/pylint#8897
+
 * Fix inference of functions with ``@functools.lru_cache`` decorators without
   parentheses.
 

astroid/brain/brain_namedtuple_enum.py

@@ -20,7 +20,6 @@
     AstroidTypeError,
     AstroidValueError,
     InferenceError,
-    MroError,
     UseInferenceDefault,
 )
 from astroid.manager import AstroidManager
@@ -31,14 +30,6 @@
     from typing_extensions import Final
 
 
-ENUM_BASE_NAMES = {
-    "Enum",
-    "IntEnum",
-    "enum.Enum",
-    "enum.IntEnum",
-    "IntFlag",
-    "enum.IntFlag",
-}
 ENUM_QNAME: Final[str] = "enum.Enum"
 TYPING_NAMEDTUPLE_QUALIFIED: Final = {
     "typing.NamedTuple",
@@ -606,14 +597,7 @@ def _get_namedtuple_fields(node: nodes.Call) -> str:
 
 def _is_enum_subclass(cls: astroid.ClassDef) -> bool:
     """Return whether cls is a subclass of an Enum."""
-    try:
-        return any(
-            klass.name in ENUM_BASE_NAMES
-            and getattr(klass.root(), "name", None) == "enum"
-            for klass in cls.mro()
-        )
-    except MroError:
-        return False
+    return cls.is_subtype_of("enum.Enum")
 
 
 AstroidManager().register_transform(

tests/brain/test_enum.py

@@ -493,3 +493,39 @@ def pear(self):
         for node in (attribute_nodes[1], name_nodes[1]):
             with pytest.raises(InferenceError):
                 node.inferred()
+
+    def test_local_enum_child_class_inference(self) -> None:
+        """Originally reported in https://github.com/pylint-dev/pylint/issues/8897
+
+        Test that a user-defined enum class is inferred when it subclasses
+        another user-defined enum class.
+        """
+        enum_class_node, enum_member_value_node = astroid.extract_node(
+            """
+        import sys
+
+        from enum import Enum
+
+        if sys.version_info >= (3, 11):
+            from enum import StrEnum
+        else:
+            class StrEnum(str, Enum):
+                pass
+
+
+        class Color(StrEnum): #@
+            RED = "red"
+
+
+        Color.RED.value #@
+        """
+        )
+        assert "RED" in enum_class_node.locals
+
+        enum_members = enum_class_node.locals["__members__"][0].items
+        assert len(enum_members) == 1
+        _, name = enum_members[0]
+        assert name.name == "RED"
+
+        inferred_enum_member_value_node = next(enum_member_value_node.infer())
+        assert inferred_enum_member_value_node.value == "red"