Tuple[A, B] + Tuple[C] = Tuple[Any, …] instead of Tuple[A, B, C]

[bwo]

from typing import Tuple 

x = (1, 't', 2)  # type: Tuple[int, str, int]

z = ('t', 3)  # type: Tuple[str, int]

xz = x + z  # type: Tuple[int, str, int, str, int]

Not only is Tuple[Any, …] the inferred type of xz, mypy won't accept the provided annotation:

error: Incompatible types in assignment (expression has type "Tuple[Any, ...]", variable has type "Tuple[int, str, int, str, int]")

Running this program through mypy:

from typing import TypeVar, Type, Mapping, Sequence, Generator, Tuple  # noqa


x = (1, 't', 2)  # type: Tuple[int, str, int]

z = ('t', 3)  # type: Tuple[str, int]

xz = x + z

reveal_type(xz[0])

shows that the type of xz[0] is now Any (consistent with the inferred type).

IMO if it's not type-theoretically onerous the inferred type of xz should be Tuple[int, str, int, str, int].

[JukkaL]

Closing as duplicate of #224.