Do not treat unassigned attributes as enum members

Author: sterliakov

mypy/checkmember.py

@@ -1342,6 +1342,7 @@ def apply_class_attr_hook(
 def analyze_enum_class_attribute_access(
     itype: Instance, name: str, mx: MemberContext
 ) -> Type | None:
+    # This function should be kept in sync with TypeInfo.enum_members
     # Skip these since Enum will remove it
     if name in EXCLUDED_ENUM_ATTRIBUTES:
         return report_missing_attribute(mx.original_type, itype, name, mx)
@@ -1350,6 +1351,9 @@ def analyze_enum_class_attribute_access(
         return None
 
     node = itype.type.get(name)
+    if not isinstance(node.node, Var) or not node.node.has_explicit_value:
+        # Annotated but not assigned attributes are not enum members
+        return None
     if node and node.type:
         proper = get_proper_type(node.type)
         # Support `A = nonmember(1)` function call and decorator.

mypy/nodes.py

@@ -3317,6 +3317,7 @@ def protocol_members(self) -> list[str]:
 
     @property
     def enum_members(self) -> list[str]:
+        # This method should be kept in sync with checkmember.analyze_enum_class_attribute_access
         # TODO: cache the results?
         members = []
         for name, sym in self.names.items():

mypy/typeanal.py

@@ -959,7 +959,7 @@ def analyze_unbound_type_without_type_info(
             isinstance(sym.node, Var)
             and sym.node.info
             and sym.node.info.is_enum
-            and not sym.node.name.startswith("__")
+            and sym.node.name in sym.node.info.enum_members
         ):
             value = sym.node.name
             base_enum_short_name = sym.node.info.name

test-data/unit/check-enum.test

@@ -457,7 +457,8 @@ class F(Generic[T], Enum):  # E: Enum class cannot be generic
     x: T
     y: T
 
-reveal_type(F[int].x)  # N: Revealed type is "__main__.F[builtins.int]"
+reveal_type(F[int].x)  # E: Access to generic instance variables via class is ambiguous \
+                       # N: Revealed type is "builtins.int"
 [builtins fixtures/enum.pyi]
 
 [case testEnumFlag]
@@ -1422,6 +1423,23 @@ class Comparator(enum.Enum):
 reveal_type(Comparator.__foo__)  # N: Revealed type is "builtins.dict[builtins.str, builtins.int]"
 [builtins fixtures/dict.pyi]
 
+[case testEnumClassAttributeUnannotated]
+import enum
+from typing import ClassVar, Literal
+
+class MyEnum(enum.Enum):
+    foo: ClassVar[str]
+    bar: str
+
+    VALUE_A = 1
+    VALUE_B = 2
+
+reveal_type(MyEnum.foo)  # N: Revealed type is "builtins.str"
+reveal_type(MyEnum.bar)  # N: Revealed type is "builtins.str"
+x: Literal[MyEnum.foo]  # E: Parameter 1 of Literal[...] is invalid
+y: Literal[MyEnum.bar]  # E: Parameter 1 of Literal[...] is invalid
+[builtins fixtures/enum.pyi]
+
 [case testEnumWithInstanceAttributes]
 from enum import Enum
 class Foo(Enum):