fixup! fixup! Support overriding dunder attributes in Enum subclass

flaeppe · flaeppe · commit de303ebdccd5 · 2022-02-07T10:01:54.000+01:00
diff --git a/mypy/checker.py b/mypy/checker.py
@@ -1901,7 +1901,7 @@ def check_enum(self, defn: ClassDef) -> None:
                     # `__members__` will always be overwritten by `Enum` and is considered
                     # read-only so we disallow assigning a value to it
                     self.fail(
-                        message_registry.CANNOT_WRITE_ENUM_READONLY_MEMBERS, sym.node
+                        message_registry.ENUM_MEMBERS_ATTR_WILL_BE_OVERRIDEN, sym.node
                     )
         for base in defn.info.mro[1:-1]:  # we don't need self and `object`
             if base.is_enum and base.fullname not in ENUM_BASES:
diff --git a/mypy/message_registry.py b/mypy/message_registry.py
@@ -205,8 +205,8 @@ def format(self, *args: object, **kwargs: object) -> "ErrorMessage":
 CANNOT_MAKE_DELETABLE_FINAL: Final = ErrorMessage("Deletable attribute cannot be final")
 
 # Enum
-CANNOT_WRITE_ENUM_READONLY_MEMBERS: Final = ErrorMessage(
-    'Cannot declare read-only attribute "__members__"'
+ENUM_MEMBERS_ATTR_WILL_BE_OVERRIDEN: Final = ErrorMessage(
+    'Assigned "__members__" will be overriden by "Enum" internally'
 )
 
 # ClassVar
diff --git a/test-data/unit/check-enum.test b/test-data/unit/check-enum.test
@@ -1923,7 +1923,7 @@ import typing
 from enum import Enum
 
 class WritingMembers(Enum):
-    __members__: typing.Dict[Enum, Enum] = {}  # E: Cannot declare read-only attribute "__members__"
+    __members__: typing.Dict[Enum, Enum] = {}  # E: Assigned "__members__" will be overriden by "Enum" internally
 
 class OnlyAnnotatedMembers(Enum):
     __members__: typing.Dict[Enum, Enum]

Original file line number	Diff line number	Diff line change
`@@ -1901,7 +1901,7 @@ def check_enum(self, defn: ClassDef) -> None:`
`1901`	`1901`	# `__members__` will always be overwritten by `Enum` and is considered
`1902`	`1902`	`# read-only so we disallow assigning a value to it`
`1903`	`1903`	`self.fail(`
`1904`		`- message_registry.CANNOT_WRITE_ENUM_READONLY_MEMBERS, sym.node`
	`1904`	`+ message_registry.ENUM_MEMBERS_ATTR_WILL_BE_OVERRIDEN, sym.node`
`1905`	`1905`	`)`
`1906`	`1906`	for base in defn.info.mro[1:-1]: # we don't need self and `object`
`1907`	`1907`	`if base.is_enum and base.fullname not in ENUM_BASES:`
Original file line number	Diff line number	Diff line change
`@@ -205,8 +205,8 @@ def format(self, args: object, *kwargs: object) -> "ErrorMessage":`
`205`	`205`	`CANNOT_MAKE_DELETABLE_FINAL: Final = ErrorMessage("Deletable attribute cannot be final")`
`206`	`206`
`207`	`207`	`# Enum`
`208`		`-CANNOT_WRITE_ENUM_READONLY_MEMBERS: Final = ErrorMessage(`
`209`		`- 'Cannot declare read-only attribute "__members__"'`
	`208`	`+ENUM_MEMBERS_ATTR_WILL_BE_OVERRIDEN: Final = ErrorMessage(`
	`209`	`+ 'Assigned "__members__" will be overriden by "Enum" internally'`
`210`	`210`	`)`
`211`	`211`
`212`	`212`	`# ClassVar`