Fix a crash when incorrect super() is used outside a method (#14208)

Ref #14201

mypy/checkexpr.py

@@ -4390,13 +4390,14 @@ def visit_super_expr(self, e: SuperExpr) -> Type:
  index = mro.index(type_info)
  else:
  method = self.chk.scope.top_function()
- assert method is not None
  # Mypy explicitly allows supertype upper bounds (and no upper bound at all)
  # for annotating self-types. However, if such an annotation is used for
  # checking super() we will still get an error. So to be consistent, we also
  # allow such imprecise annotations for use with super(), where we fall back
- # to the current class MRO instead.
- if is_self_type_like(instance_type, is_classmethod=method.is_class):
+ # to the current class MRO instead. This works only from inside a method.
+ if method is not None and is_self_type_like(
+ instance_type, is_classmethod=method.is_class
+ ):
  if e.info and type_info in e.info.mro:
  mro = e.info.mro
  index = mro.index(type_info)

test-data/unit/check-super.test

@@ -409,3 +409,10 @@ class B(A):
  reveal_type(super().foo()) # N: Revealed type is "T`-1"
  return super().foo()
 [builtins fixtures/classmethod.pyi]
+
+[case testWrongSuperOutsideMethodNoCrash]
+class B:
+ x: int
+class C1(B): ...
+class C2(B): ...
+super(C1, C2).x # E: Argument 2 for "super" not an instance of argument 1