Remove some Python 2 type checking logic (#13261)

mypy/checker.py

@@ -469,10 +469,6 @@ def check_first_pass(self) -> None:
  seq_str = self.named_generic_type(
  "typing.Sequence", [self.named_type("builtins.str")]
  )
- if self.options.python_version[0] < 3:
- seq_str = self.named_generic_type(
- "typing.Sequence", [self.named_type("builtins.unicode")]
- )
  if not is_subtype(all_.type, seq_str):
  str_seq_s, all_s = format_type_distinctly(seq_str, all_.type)
  self.fail(
@@ -1093,18 +1089,6 @@ def check_func_def(self, defn: FuncItem, typ: CallableType, name: Optional[str])
  if not self.is_generator_return_type(typ.ret_type, defn.is_coroutine):
  self.fail(message_registry.INVALID_RETURN_TYPE_FOR_GENERATOR, typ)
 
- # Python 2 generators aren't allowed to return values.
- orig_ret_type = get_proper_type(typ.ret_type)
- if (
- self.options.python_version[0] == 2
- and isinstance(orig_ret_type, Instance)
- and orig_ret_type.type.fullname == "typing.Generator"
- ):
- if not isinstance(
- get_proper_type(orig_ret_type.args[2]), (NoneType, AnyType)
- ):
- self.fail(message_registry.INVALID_GENERATOR_RETURN_ITEM_TYPE, typ)
-
  # Fix the type if decorated with `@types.coroutine` or `@asyncio.coroutine`.
  if defn.is_awaitable_coroutine:
  # Update the return type to AwaitableGenerator.
@@ -1145,7 +1129,6 @@ def check_func_def(self, defn: FuncItem, typ: CallableType, name: Optional[str])
  ref_type = mypy.types.TypeType.make_normalized(ref_type)
  erased = get_proper_type(erase_to_bound(arg_type))
  if not is_subtype(ref_type, erased, ignore_type_params=True):
- note = None
  if (
  isinstance(erased, Instance)
  and erased.type.is_protocol
@@ -1158,23 +1141,13 @@ def check_func_def(self, defn: FuncItem, typ: CallableType, name: Optional[str])
  # the consistency check will be performed at call sites.
  msg = None
  elif typ.arg_names[i] in {"self", "cls"}:
- if (
- self.options.python_version[0] < 3
- and is_same_type(erased, arg_type)
- and not isclass
- ):
- msg = message_registry.INVALID_SELF_TYPE_OR_EXTRA_ARG
- note = "(Hint: typically annotations omit the type for self)"
- else:
- msg = message_registry.ERASED_SELF_TYPE_NOT_SUPERTYPE.format(
- erased, ref_type
- )
+ msg = message_registry.ERASED_SELF_TYPE_NOT_SUPERTYPE.format(
+ erased, ref_type
+ )
  else:
  msg = message_registry.MISSING_OR_INVALID_SELF_TYPE
  if msg:
  self.fail(msg, defn)
- if note:
- self.note(note, defn)
  elif isinstance(arg_type, TypeVarType):
  # Refuse covariant parameter type variables
  # TODO: check recursively for inner type variables
@@ -1287,16 +1260,10 @@ def check_default_args(self, item: FuncItem, body_is_trivial: bool) -> None:
  )
 
  def is_forward_op_method(self, method_name: str) -> bool:
- if self.options.python_version[0] == 2 and method_name == "__div__":
- return True
- else:
- return method_name in operators.reverse_op_methods
+ return method_name in operators.reverse_op_methods
 
  def is_reverse_op_method(self, method_name: str) -> bool:
- if self.options.python_version[0] == 2 and method_name == "__rdiv__":
- return True
- else:
- return method_name in operators.reverse_op_method_set
+ return method_name in operators.reverse_op_method_set
 
  def check_for_missing_annotations(self, fdef: FuncItem) -> None:
  # Check for functions with unspecified/not fully specified types.
@@ -1459,10 +1426,7 @@ def check_reverse_op_method(
  )
  assert len(reverse_type.arg_types) >= 2
 
- if self.options.python_version[0] == 2 and reverse_name == "__rdiv__":
- forward_name = "__div__"
- else:
- forward_name = operators.normal_from_reverse_op[reverse_name]
+ forward_name = operators.normal_from_reverse_op[reverse_name]
  forward_inst = get_proper_type(reverse_type.arg_types[1])
  if isinstance(forward_inst, TypeVarType):
  forward_inst = get_proper_type(forward_inst.upper_bound)
@@ -4198,20 +4162,10 @@ def visit_try_without_finally(self, s: TryStmt, try_frame: bool) -> None:
  self.accept(s.handlers[i])
  var = s.vars[i]
  if var:
- # Exception variables are deleted in python 3 but not python 2.
- # But, since it's bad form in python 2 and the type checking
- # wouldn't work very well, we delete it anyway.
-
+ # Exception variables are deleted.
  # Unfortunately, this doesn't let us detect usage before the
  # try/except block.
- if self.options.python_version[0] >= 3:
- source = var.name
- else:
- source = (
- '(exception variable "{}", which we do not '
- "accept outside except: blocks even in "
- "python 2)".format(var.name)
- )
+ source = var.name
  if isinstance(var.node, Var):
  var.node.type = DeletedType(source=source)
  self.binder.cleanse(var)
@@ -4302,11 +4256,7 @@ def analyze_iterable_item_type(self, expr: Expression) -> Tuple[Type, Type]:
  return iterator, joined
  else:
  # Non-tuple iterable.
- if self.options.python_version[0] >= 3:
- nextmethod = "__next__"
- else:
- nextmethod = "next"
- return iterator, echk.check_method_call_by_name(nextmethod, iterator, [], [], expr)[0]
+ return iterator, echk.check_method_call_by_name("__next__", iterator, [], [], expr)[0]
 
  def analyze_container_item_type(self, typ: Type) -> Optional[Type]:
  """Check if a type is a nominal container of a union of such.

mypy/message_registry.py

@@ -45,10 +45,6 @@ def format(self, *args: object, **kwargs: object) -> "ErrorMessage":
  'The return type of an async generator function should be "AsyncGenerator" or one of its '
  "supertypes"
 )
-INVALID_GENERATOR_RETURN_ITEM_TYPE: Final = ErrorMessage(
- "The return type of a generator function must be None in"
- " its third type parameter in Python 2"
-)
 YIELD_VALUE_EXPECTED: Final = ErrorMessage("Yield value expected")
 INCOMPATIBLE_TYPES: Final = "Incompatible types"
 INCOMPATIBLE_TYPES_IN_ASSIGNMENT: Final = "Incompatible types in assignment"
@@ -203,9 +199,6 @@ def format(self, *args: object, **kwargs: object) -> "ErrorMessage":
 ERASED_SELF_TYPE_NOT_SUPERTYPE: Final = ErrorMessage(
  'The erased type of self "{}" is not a supertype of its class "{}"'
 )
-INVALID_SELF_TYPE_OR_EXTRA_ARG: Final = ErrorMessage(
- "Invalid type for self, or extra argument type in function annotation"
-)
 
 # Final
 CANNOT_INHERIT_FROM_FINAL: Final = ErrorMessage('Cannot inherit from final class "{}"')