Clear type alias flag for assignments that are not aliases (#11446)

This flag may be set to `True` if there are tricky forward references.

Co-authored-by: Ivan Levkivskyi <[email protected]>

Author: ilevkivskyi

mypy/semanal.py

@@ -2032,9 +2032,13 @@ def visit_assignment_stmt(self, s: AssignmentStmt) -> None:
             special_form = True
         elif self.analyze_enum_assign(s):
             special_form = True
+
         if special_form:
             self.record_special_form_lvalue(s)
             return
+        # Clear the alias flag if assignment turns out not a special form after all. It
+        # may be set to True while there were still placeholders due to forward refs.
+        s.is_alias_def = False
 
         # OK, this is a regular assignment, perform the necessary analysis steps.
         s.is_final_def = self.unwrap_final(s)

test-data/unit/check-callable.test

@@ -484,3 +484,56 @@ reveal_type(_TYPE)  # N: Revealed type is "def (x: Any) -> builtins.type"
 _TYPE('bar')
 
 [builtins fixtures/callable.pyi]
+
+[case testErrorMessageAboutSelf]
+# https://github.com/python/mypy/issues/11309
+class Some:
+    def method(self, a) -> None: pass
+    @classmethod
+    def cls_method(cls, a) -> None: pass
+    @staticmethod
+    def st_method(a) -> None: pass
+
+    def bad_method(a) -> None: pass
+    @classmethod
+    def bad_cls_method(a) -> None: pass
+    @staticmethod
+    def bad_st_method() -> None: pass
+
+s: Some
+
+s.method(1)
+s.cls_method(1)
+Some.cls_method(1)
+s.st_method(1)
+Some.st_method(1)
+
+s.method(1, 2)  # E: Too many arguments for "method" of "Some"
+s.cls_method(1, 2)  # E: Too many arguments for "cls_method" of "Some"
+Some.cls_method(1, 2)  # E: Too many arguments for "cls_method" of "Some"
+s.st_method(1, 2)  # E: Too many arguments for "st_method" of "Some"
+Some.st_method(1, 2)  # E: Too many arguments for "st_method" of "Some"
+
+s.bad_method(1)  # E: Too many arguments for "bad_method" of "Some" \
+                 # N: Looks like the first special argument in a method is not named "self", "cls", or "mcs", maybe it is missing?
+s.bad_cls_method(1)  # E: Too many arguments for "bad_cls_method" of "Some" \
+                     # N: Looks like the first special argument in a method is not named "self", "cls", or "mcs", maybe it is missing?
+Some.bad_cls_method(1)  # E: Too many arguments for "bad_cls_method" of "Some" \
+                        # N: Looks like the first special argument in a method is not named "self", "cls", or "mcs", maybe it is missing?
+s.bad_st_method(1)  # E: Too many arguments for "bad_st_method" of "Some"
+Some.bad_st_method(1)  # E: Too many arguments for "bad_st_method" of "Some"
+[builtins fixtures/callable.pyi]
+
+[case testClassMethodAliasStub]
+from a import f
+f("no")  # E: Argument 1 has incompatible type "str"; expected "int"
+[file a.pyi]
+from b import C
+f = C.f
+[file b.pyi]
+import a
+class C(B):
+    @classmethod
+    def f(self, x: int) -> C: ...
+class B: ...
+[builtins fixtures/classmethod.pyi]