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Support _value_ as a fallback for ellipsis Enum members #19352

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Support _value_ as a fallback for ellipsis Enum members #19352

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9666276
Use _value_ as a fallback for ellipsis Enum members
sterliakov Jun 27, 2025
80c82b7
Sync failing tests
sterliakov Jun 28, 2025
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16 changes: 15 additions & 1 deletion mypy/plugins/enums.py
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@
from typing import Final, TypeVar, cast

import mypy.plugin # To avoid circular imports.
from mypy.nodes import TypeInfo
from mypy.nodes import TypeInfo, Var
from mypy.semanal_enum import ENUM_BASES
from mypy.subtypes import is_equivalent
from mypy.typeops import fixup_partial_type, make_simplified_union
Expand Down Expand Up @@ -87,6 +87,20 @@ def _infer_value_type_with_auto_fallback(
if proper_type is None:
return None
proper_type = get_proper_type(fixup_partial_type(proper_type))
# Enums in stubs may have ... instead of actual values. If `_value_` is annotated
# (manually or inherited from IntEnum, for example), it is a more reasonable guess
# than literal ellipsis type.
if isinstance(proper_type, Instance) and proper_type.type.fullname in {
"types.EllipsisType",
"builtins.ellipsis",
}:
Comment on lines +93 to +96
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There's at least one other use of this set elsewhere. Could consider moving it to a ELLIPSIS_TYPE_NAMES constant

if (
isinstance(ctx.type, Instance)
and (value_type := ctx.type.type.get("_value_"))
and isinstance(var := value_type.node, Var)
):
return var.type
return proper_type
if not (isinstance(proper_type, Instance) and proper_type.type.fullname == "enum.auto"):
if is_named_instance(proper_type, "enum.member") and proper_type.args:
return proper_type.args[0]
Expand Down
64 changes: 55 additions & 9 deletions test-data/unit/check-enum.test
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Original file line number Diff line number Diff line change
Expand Up @@ -619,8 +619,8 @@ reveal_type(A.x.name) # N: Revealed type is "Literal['x']?"
reveal_type(B.a.name) # N: Revealed type is "Literal['a']?"

# TODO: The revealed type should be 'int' here
reveal_type(A.x.value) # N: Revealed type is "Any"
reveal_type(B.a.value) # N: Revealed type is "Any"
reveal_type(A.x.value) # N: Revealed type is "builtins.int"
reveal_type(B.a.value) # N: Revealed type is "builtins.int"
[builtins fixtures/enum.pyi]

[case testAnonymousFunctionalEnum]
Expand Down Expand Up @@ -755,12 +755,10 @@ class B2(IntEnum):
class B3(IntEnum):
x = 1

# TODO: getting B1.x._value_ and B2.x._value_ to have type 'int' requires a typeshed change

is_x(reveal_type(B1.x.name)) # N: Revealed type is "Literal['x']"
is_x(reveal_type(B1.x._name_)) # N: Revealed type is "Literal['x']"
reveal_type(B1.x.value) # N: Revealed type is "builtins.int"
reveal_type(B1.x._value_) # N: Revealed type is "Any"
reveal_type(B1.x._value_) # N: Revealed type is "builtins.int"
is_x(reveal_type(B2.x.name)) # N: Revealed type is "Literal['x']"
is_x(reveal_type(B2.x._name_)) # N: Revealed type is "Literal['x']"
reveal_type(B2.x.value) # N: Revealed type is "builtins.int"
Expand All @@ -781,8 +779,8 @@ class C3(IntFlag):

is_x(reveal_type(C1.x.name)) # N: Revealed type is "Literal['x']"
is_x(reveal_type(C1.x._name_)) # N: Revealed type is "Literal['x']"
reveal_type(C1.x.value) # N: Revealed type is "Any"
reveal_type(C1.x._value_) # N: Revealed type is "Any"
reveal_type(C1.x.value) # N: Revealed type is "builtins.int"
reveal_type(C1.x._value_) # N: Revealed type is "builtins.int"
is_x(reveal_type(C2.x.name)) # N: Revealed type is "Literal['x']"
is_x(reveal_type(C2.x._name_)) # N: Revealed type is "Literal['x']"
reveal_type(C2.x.value) # N: Revealed type is "builtins.int"
Expand All @@ -800,8 +798,8 @@ class D3(Flag):

is_x(reveal_type(D1.x.name)) # N: Revealed type is "Literal['x']"
is_x(reveal_type(D1.x._name_)) # N: Revealed type is "Literal['x']"
reveal_type(D1.x.value) # N: Revealed type is "Any"
reveal_type(D1.x._value_) # N: Revealed type is "Any"
reveal_type(D1.x.value) # N: Revealed type is "builtins.int"
reveal_type(D1.x._value_) # N: Revealed type is "builtins.int"
is_x(reveal_type(D2.x.name)) # N: Revealed type is "Literal['x']"
is_x(reveal_type(D2.x._name_)) # N: Revealed type is "Literal['x']"
reveal_type(D2.x.value) # N: Revealed type is "builtins.int"
Expand Down Expand Up @@ -2539,3 +2537,51 @@ def check(thing: Things) -> None:
return None
return None # E: Statement is unreachable
[builtins fixtures/enum.pyi]

[case testSunderValueType]
from enum import Enum, IntEnum, StrEnum, Flag, IntFlag

class Basic(Enum):
_value_: int
FOO = 1

reveal_type(Basic.FOO) # N: Revealed type is "Literal[__main__.Basic.FOO]?"
reveal_type(Basic.FOO.value) # N: Revealed type is "Literal[1]?"
reveal_type(Basic.FOO._value_) # N: Revealed type is "builtins.int"

class FromStub(Enum):
_value_: int
FOO = ...

reveal_type(FromStub.FOO) # N: Revealed type is "Literal[__main__.FromStub.FOO]?"
reveal_type(FromStub.FOO.value) # N: Revealed type is "builtins.int"
reveal_type(FromStub.FOO._value_) # N: Revealed type is "builtins.int"

class InheritedInt(IntEnum):
FOO = ...

reveal_type(InheritedInt.FOO) # N: Revealed type is "Literal[__main__.InheritedInt.FOO]?"
reveal_type(InheritedInt.FOO.value) # N: Revealed type is "builtins.int"
reveal_type(InheritedInt.FOO._value_) # N: Revealed type is "builtins.int"

class InheritedStr(StrEnum):
FOO = ...

reveal_type(InheritedStr.FOO) # N: Revealed type is "Literal[__main__.InheritedStr.FOO]?"
reveal_type(InheritedStr.FOO.value) # N: Revealed type is "builtins.str"
reveal_type(InheritedStr.FOO._value_) # N: Revealed type is "builtins.str"

class InheritedFlag(Flag):
FOO = ...

reveal_type(InheritedFlag.FOO) # N: Revealed type is "Literal[__main__.InheritedFlag.FOO]?"
reveal_type(InheritedFlag.FOO.value) # N: Revealed type is "builtins.int"
reveal_type(InheritedFlag.FOO._value_) # N: Revealed type is "builtins.int"

class InheritedIntFlag(IntFlag):
FOO = ...

reveal_type(InheritedIntFlag.FOO) # N: Revealed type is "Literal[__main__.InheritedIntFlag.FOO]?"
reveal_type(InheritedIntFlag.FOO.value) # N: Revealed type is "builtins.int"
reveal_type(InheritedIntFlag.FOO._value_) # N: Revealed type is "builtins.int"
[builtins fixtures/enum.pyi]
5 changes: 5 additions & 0 deletions test-data/unit/lib-stub/enum.pyi
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Original file line number Diff line number Diff line change
Expand Up @@ -29,13 +29,16 @@ class Enum(metaclass=EnumMeta):

class IntEnum(int, Enum):
value: int
_value_: int
def __new__(cls: Type[_T], value: Union[int, _T]) -> _T: ...

def unique(enumeration: _T) -> _T: pass

# In reality Flag and IntFlag are 3.6 only

class Flag(Enum):
value: int
_value_: int
def __or__(self: _T, other: Union[int, _T]) -> _T: pass


Expand All @@ -49,6 +52,8 @@ class auto(IntFlag):

# It is python-3.11+ only:
class StrEnum(str, Enum):
_value_: str
value: str
def __new__(cls: Type[_T], value: str | _T) -> _T: ...

# It is python-3.11+ only:
Expand Down