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fix detection of whether MemberExpr.expr represents self/cls in… #20480

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Merged
hauntsaninja merged 1 commit into from
Dec 27, 2025
Merged

fix detection of whether MemberExpr.expr represents self/cls in… #20480

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12 changes: 8 additions & 4 deletions mypy/semanal.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6091,10 +6091,14 @@ def visit_member_expr(self, expr: MemberExpr) -> None:
elif isinstance(base.node, Var) and self.type and self.function_stack:
# check for self.bar or cls.bar in method/classmethod
func_def = self.function_stack[-1]
if not func_def.is_static and isinstance(func_def.type, CallableType):
formal_arg = func_def.type.argument_by_name(base.node.name)
if formal_arg and formal_arg.pos == 0:
type_info = self.type
if (
func_def.has_self_or_cls_argument
and func_def.info is self.type
and isinstance(func_def.type, CallableType)
and func_def.arguments
and base.node is func_def.arguments[0].variable
):
type_info = self.type
elif isinstance(base.node, TypeAlias) and base.node.no_args:
assert isinstance(base.node.target, ProperType)
if isinstance(base.node.target, Instance):
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31 changes: 31 additions & 0 deletions test-data/unit/check-classes.test
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Expand Up @@ -8328,6 +8328,37 @@ reveal_type(Foo.baz) # E: "type[Foo]" has no attribute "baz" \
foo: int
def bar(x: int) -> int: ...

[case testClassScopeImportAccessibleInMethods]
class A:
import mod
from mod import var

def __new__(cls) -> "A":
reveal_type(cls.mod) # N: Revealed type is "types.ModuleType"
reveal_type(cls.var) # N: Revealed type is "builtins.int"
reveal_type(cls.mod.var) # N: Revealed type is "builtins.int"
return cls()

def pos_or_named_self(self) -> None:
reveal_type(self.mod) # N: Revealed type is "types.ModuleType"
reveal_type(self.var) # N: Revealed type is "builtins.int"
reveal_type(self.mod.var) # N: Revealed type is "builtins.int"

def pos_only_self(self, /) -> None:
reveal_type(self.mod) # N: Revealed type is "types.ModuleType"
reveal_type(self.var) # N: Revealed type is "builtins.int"
reveal_type(self.mod.var) # N: Revealed type is "builtins.int"

@classmethod
def clsmethod(cls) -> None:
reveal_type(cls.mod) # N: Revealed type is "types.ModuleType"
reveal_type(cls.var) # N: Revealed type is "builtins.int"
reveal_type(cls.mod.var) # N: Revealed type is "builtins.int"

[file mod.py]
var = 1
[builtins fixtures/module.pyi]

Comment on lines +8331 to +8361
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@bzoracler bzoracler Dec 27, 2025 •
edited
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.mod.var was revealed to be Any in the body of __new__() and pos_only_self() before this PR. See e.g. mypy Playground for a reproducer:

class A:
    import math

    def __new__(cls) -> "A":
        reveal_type(cls.math.pi)  # N: Revealed type is "Any"
        return cls()

    def pos_or_named_self(self) -> None:
        reveal_type(self.math.pi)  # N: Revealed type is "builtins.float"

    def pos_only_self(self, /) -> None:
        reveal_type(self.math.pi)  # N: Revealed type is "Any"

    @classmethod
    def clsmethod(cls) -> None:
        reveal_type(cls.math.pi)  # N: Revealed type is "builtins.float"

[case testClassScopeImportFunctionNested]
class Foo:
class Bar:
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13 changes: 13 additions & 0 deletions test-data/unit/check-functions.test
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Expand Up @@ -782,6 +782,19 @@ class A:
# type: () -> None
pass

[case testNestedFunctionInMethodCannotAccessEnclosingClassAttributes]
class A:
var: int
import mod
class B: ...

def method(self) -> None:
def f1(arg: object) -> None:
arg.var # E: "object" has no attribute "var"
arg.mod # E: "object" has no attribute "mod"
arg.B # E: "object" has no attribute "B"
[file mod.py]

[case testDeepNestedFunctionWithTooFewArgumentsInTypeComment]
class A:
def f(self):
Expand Down