Fix overloads for all and from_input to not return Never types (#16139

)

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# Description

<!--- Please include a summary of the change and which issue is fixed.
Please also include relevant motivation and context. -->

Fixes #16027.

Seems mypy was having issues with Outputs being passed into these
methods and tracking that they should have just been returning the same
Output in the result. Adding these extra overloads seems to have
appeased the type checker when using these methods.

## Checklist

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- [x] I have run `make lint` to verify my code passes the lint check
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- [ ] I have added tests that prove my fix is effective or that my
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changelog/pending/20240507--sdk-python--fix-typings-for-from_input-and-all-to-not-return-never-types.yaml

@@ -0,0 +1,4 @@
+changes:
+- type: fix
+ scope: sdk/python
+ description: Fix typings for `from_input` and `all` to not return `Never` types.

sdk/python/lib/pulumi/output.py

@@ -154,7 +154,7 @@ def is_secret(self) -> Awaitable[bool]:
  return self._is_secret
 
  def apply(
- self, func: Callable[[T_co], Input[U]], run_with_unknowns: Optional[bool] = None
+ self, func: Callable[[T_co], Input[U]], run_with_unknowns: bool = False
  ) -> "Output[U]":
  """
  Transforms the data of the output with the provided func. The result remains an
@@ -285,6 +285,14 @@ def __iter__(self) -> Any:
  "'Output' object is not iterable, consider iterating the underlying value inside an 'apply'"
  )
 
+ @overload
+ @staticmethod
+ def from_input(val: "Output[T_co]") -> "Output[T_co]": ...
+
+ @overload
+ @staticmethod
+ def from_input(val: Input[T_co]) -> "Output[T_co]": ...
+
  @staticmethod
  def from_input(val: Input[T_co]) -> "Output[T_co]":
  """
@@ -425,15 +433,22 @@ def secret(val: Input[T]) -> "Output[T]":
  # https://mypy.readthedocs.io/en/stable/more_types.html#type-checking-the-variants:~:text=considered%20unsafely%20overlapping
  @overload
  @staticmethod
- def all(*args: Input[T]) -> "Output[List[T]]": # type: ignore
- ...
+ def all(*args: "Output[T_co]") -> "Output[List[T_co]]": ... # type: ignore
+
+ @overload
+ @staticmethod
+ def all(**kwargs: "Output[T_co]") -> "Output[Dict[str, T_co]]": ... # type: ignore
 
  @overload
  @staticmethod
- def all(**kwargs: Input[T]) -> "Output[Dict[str, T]]": ...
+ def all(*args: Input[T_co]) -> "Output[List[T_co]]": ... # type: ignore
 
+ @overload
  @staticmethod
- def all(*args: Input[T], **kwargs: Input[T]):
+ def all(**kwargs: Input[T_co]) -> "Output[Dict[str, T_co]]": ... # type: ignore
+
+ @staticmethod
+ def all(*args: Input[T_co], **kwargs: Input[T_co]):
  """
  Produces an Output of a list (if args i.e a list of inputs are supplied)
  or dict (if kwargs i.e. keyworded arguments are supplied).
@@ -486,19 +501,15 @@ async def gather_futures(outputs: Union[dict, list]):
  }
  return await _gather_from_dict(value_futures_dict)
 
- from_input = cast(
- Callable[[Union[T, Awaitable[T], Output[T]]], Output[T]], Output.from_input
- )
-
  if args and kwargs:
  raise ValueError(
  "Output.all() was supplied a mix of named and unnamed inputs"
  )
  # First, map all inputs to outputs using `from_input`.
  all_outputs: Union[list, dict] = (
- {k: from_input(v) for k, v in kwargs.items()}
+ {k: Output.from_input(v) for k, v in kwargs.items()}
  if kwargs
- else [from_input(x) for x in args]
+ else [Output.from_input(x) for x in args]
  )
 
  # Aggregate the list or dict of futures into a future of list or dict.