Overloaded function signature will never be matched

[chiamp]

Bug Report
I get the following error when I add **init_kwargs to the first overloaded function signature. If I remove it (but keep **init_kwargs in all of the other function signatures), there's no error.

flax/linen/module.py:1664: error: Overloaded function signature 2 will never be matched: signature 1's parameter type(s) are the same or broader  [misc]
flax/linen/module.py:1675: error: Overloaded function signature 3 will never be matched: signature 1's parameter type(s) are the same or broader  [misc]
flax/linen/module.py:1686: error: Overloaded function signature 4 will never be matched: signature 1's parameter type(s) are the same or broader  [misc]

To Reproduce

  @overload
  def param(
    self, name: str, init_fn: Callable[..., T], *init_args, **init_kwargs,
  ) -> T:
    ...

  @overload
  def param(
    self,
    name: str,
    init_fn: Callable[..., T],
    *init_args,
    unbox: Literal[True],
    **init_kwargs,
  ) -> T:
    ...

  @overload
  def param(
    self,
    name: str,
    init_fn: Callable[..., T],
    *init_args,
    unbox: Literal[False],
    **init_kwargs,
  ) -> meta.AxisMetadata[T]:
    ...

  @overload
  def param(
    self,
    name: str,
    init_fn: Callable[..., T],
    *init_args,
    unbox: bool,
    **init_kwargs,
  ) -> Union[T, meta.AxisMetadata[T]]:
    ...

  def param(
    self,
    name: str,
    init_fn: Callable[..., T],
    *init_args,
    unbox: bool = True,
    **init_kwargs,
  ) -> Union[T, meta.AxisMetadata[T]]:

Expected Behavior

Actual Behavior

Your Environment

• Mypy version used: mypy 1.8.0 (compiled: yes)
• Python version used: 3.9.6

[hauntsaninja]

This is a correct error. **init_kwargs will match all kwargs, so the second overload will never get matched