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Bind self-types in checkmember for decorated classmethods #19025

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Bind self-types in checkmember for decorated classmethods #19025

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380e2ba
Bind selftypes in decorated classmethods
sterliakov May 4, 2025
4442e4a
Fix typing
sterliakov May 4, 2025
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8 changes: 7 additions & 1 deletion mypy/checkmember.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1203,9 +1203,15 @@ def analyze_class_attribute_access(
t = get_proper_type(t)
if isinstance(t, FunctionLike) and is_classmethod:
t = check_self_arg(t, mx.self_type, False, mx.context, name, mx.msg)
result = add_class_tvars(
t = add_class_tvars(
t, isuper, is_classmethod, is_staticmethod, mx.self_type, original_vars=original_vars
)
if is_decorated and not is_staticmethod:
t = expand_self_type_if_needed(
t, mx, cast(Decorator, node.node).var, itype, is_class=is_classmethod
)

result = t
# __set__ is not called on class objects.
if not mx.is_lvalue:
result = analyze_descriptor_access(result, mx)
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41 changes: 41 additions & 0 deletions test-data/unit/check-selftype.test
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Expand Up @@ -2221,3 +2221,44 @@ class B:
class C(A, B): # OK: both methods take Self
pass
[builtins fixtures/tuple.pyi]

[case testSelfInFuncDecoratedClassmethod]
from collections.abc import Callable
from typing import Self, TypeVar

T = TypeVar("T")

def debug(make: Callable[[type[T]], T]) -> Callable[[type[T]], T]:
return make

class Foo:
@classmethod
@debug
def make(cls) -> Self:
return cls()

class Bar(Foo): ...

reveal_type(Foo.make()) # N: Revealed type is "__main__.Foo"
reveal_type(Foo().make()) # N: Revealed type is "__main__.Foo"
reveal_type(Bar.make()) # N: Revealed type is "__main__.Bar"
reveal_type(Bar().make()) # N: Revealed type is "__main__.Bar"
[builtins fixtures/tuple.pyi]

[case testSelfInClassDecoratedClassmethod]
from typing import Callable, Generic, TypeVar, Self

T = TypeVar("T")

class W(Generic[T]):
def __init__(self, fn: Callable[..., T]) -> None: ...
def __call__(self) -> T: ...

class Check:
@W
def foo(self) -> Self:
...

reveal_type(Check.foo()) # N: Revealed type is "def () -> __main__.Check"
reveal_type(Check().foo()) # N: Revealed type is "__main__.Check"
[builtins fixtures/tuple.pyi]