Fix whether MemberExpr.expr represent self/cls inside methods (#20480)

bzoracler · web-flow · commit 1c866bf0e7ae · 2025-12-27T12:39:44.000-08:00
Fixes #20479.
diff --git a/mypy/semanal.py b/mypy/semanal.py
@@ -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):
diff --git a/test-data/unit/check-classes.test b/test-data/unit/check-classes.test
@@ -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]
+
 [case testClassScopeImportFunctionNested]
 class Foo:
     class Bar:
diff --git a/test-data/unit/check-functions.test b/test-data/unit/check-functions.test
@@ -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):
