Fix the logic in active self-type calculation for current scope

mypy/checker.py

@@ -877,8 +877,10 @@ def check_func_def(self, defn: FuncItem, typ: CallableType, name: Optional[str])
  # Store argument types.
  for i in range(len(typ.arg_types)):
  arg_type = typ.arg_types[i]
-
- ref_type = self.scope.active_self_type() # type: Optional[Type]
+ with self.scope.push_function(defn):
+ # We temporary push the definition to get the self type as
+ # visible from *inside* of this function/method.
+ ref_type = self.scope.active_self_type() # type: Optional[Type]
  if (isinstance(defn, FuncDef) and ref_type is not None and i == 0
  and not defn.is_static
  and typ.arg_kinds[0] not in [nodes.ARG_STAR, nodes.ARG_STAR2]):
@@ -4456,6 +4458,7 @@ def active_class(self) -> Optional[TypeInfo]:
  return None
 
  def enclosing_class(self) -> Optional[TypeInfo]:
+ """Is there a class *directly* enclosing this function?"""
  top = self.top_function()
  assert top, "This method must be called from inside a function"
  index = self.stack.index(top)
@@ -4466,7 +4469,14 @@ def enclosing_class(self) -> Optional[TypeInfo]:
  return None
 
  def active_self_type(self) -> Optional[Union[Instance, TupleType]]:
+ """An instance or tuple type representing the current class.
+
+ This returns None unless we are in class body or in a method.
+ In particular, inside a function nested in method this returns None.
+ """
  info = self.active_class()
+ if not info and self.top_function():
+ info = self.enclosing_class()
  if info:
  return fill_typevars(info)
  return None

test-data/unit/check-classes.test

@@ -6077,3 +6077,15 @@ TX = TypeVar('TX', bound='X')
 class X:
  def __new__(cls, x: TX) -> TX: # E: "__new__" must return a class instance (got "TX")
  pass
+
+[case testGenericOverride]
+from typing import Generic, TypeVar, Any
+
+T = TypeVar('T')
+
+class B(Generic[T]):
+ x: T
+
+class C(B):
+ def __init__(self) -> None:
+ self.x: Any