This is related to#1439. Currently, thetyping specs say:

Only a single type variable tuple may appear in a type parameter list:

classArray(Generic[*Ts1,*Ts2]): ...# Error

In practice, this restriction seems to only apply to type parameters specified on generictypes, not generic functions/methods. mypy and pyright accepts multipleTypeVarTuples in the latter, and can even solve for them indirectly:

fromcollections.abcimportCallabledefconcat_args_and_ret[*A,*R](f:Callable[[*A],tuple[*R]],/#`-> tuple[*A, *R]` is rejected, but mypy and pyright can use#`-> tuple[*A, *tuple[*R]]` to solve `R`)->tuple[*A,*tuple[*R]]: ...deff(a:int,b:str,c:bytes,/)->tuple[float,None]: ...reveal_type(concat_args_and_ret(f))# tuple[int, str, bytes, float, None]

The ambiguity mentioned in the specs,x: Array[int, str, bool] # Ts1 = ???, Ts2 = ???, seems to only apply when type arguments are provided to a generic type likeArray (or in C++ terminology,explicit rather thandeduced). The ambiguity currently does not even seem possible with functions/methods, as they can't be subscripted. So,

1. Can we still expect multipleTypeVarTuples to be allowed for generic functions/methods (def concat_args_and_ret[*A, *R]) in the future?
2. If 1. is true, can we expect some level of support for solving items like-> tuple[*A, *R] (perhaps indirectly, like -> tuple[*A, *tuple[*R]])?