Fix todo in tarfile for modes with pipe char

[kbaikov]

Fixes #12182

@srittau please take a look.

PS.
Why do you have an overload for name: StrOrBytesPath | None = None and name: StrOrBytesPath | None ?

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

vision (https://github.com/pytorch/vision)
+ torchvision/datasets/utils.py:215: note:     def open(name: str | bytes | PathLike[str] | PathLike[bytes] | Buffer | None = ..., *, mode: Literal['r|*', 'r|', 'r|gz', 'r|bz2', 'r|xz'], fileobj: IO[bytes] | None = ..., bufsize: int = ..., format: int | None = ..., tarinfo: type[TarInfo] | None = ..., dereference: bool | None = ..., ignore_zeros: bool | None = ..., encoding: str | None = ..., errors: str = ..., pax_headers: Mapping[str, str] | None = ..., debug: int | None = ..., errorlevel: int | None = ..., preset: int | None = ...) -> TarFile
- torchvision/datasets/utils.py:215: note:     def open(name: str | bytes | PathLike[str] | PathLike[bytes] | None = ..., *, mode: str, fileobj: IO[bytes] | None = ..., bufsize: int = ..., format: int | None = ..., tarinfo: type[TarInfo] | None = ..., dereference: bool | None = ..., ignore_zeros: bool | None = ..., encoding: str | None = ..., errors: str = ..., pax_headers: Mapping[str, str] | None = ..., debug: int | None = ..., errorlevel: int | None = ..., preset: int | None = ...) -> TarFile
+ torchvision/datasets/utils.py:215: note:     def open(name: str | bytes | PathLike[str] | PathLike[bytes] | Buffer | None = ..., *, mode: Literal['w|', 'w|gz', 'w|bz2', 'w|xz'], fileobj: IO[bytes] | None = ..., bufsize: int = ..., format: int | None = ..., tarinfo: type[TarInfo] | None = ..., dereference: bool | None = ..., ignore_zeros: bool | None = ..., encoding: str | None = ..., errors: str = ..., pax_headers: Mapping[str, str] | None = ..., debug: int | None = ..., errorlevel: int | None = ..., preset: int | None = ...) -> TarFile

pip (https://github.com/pypa/pip)
+ src/pip/_internal/utils/unpacking.py:179: note:     def open(name: str | bytes | PathLike[str] | PathLike[bytes] | Buffer | None = ..., *, mode: Literal['r|*', 'r|', 'r|gz', 'r|bz2', 'r|xz'], fileobj: IO[bytes] | None = ..., bufsize: int = ..., format: int | None = ..., tarinfo: type[TarInfo] | None = ..., dereference: bool | None = ..., ignore_zeros: bool | None = ..., encoding: str | None = ..., errors: str = ..., pax_headers: Mapping[str, str] | None = ..., debug: int | None = ..., errorlevel: int | None = ..., preset: int | None = ...) -> TarFile
- src/pip/_internal/utils/unpacking.py:179: note:     def open(name: str | bytes | PathLike[str] | PathLike[bytes] | None = ..., *, mode: str, fileobj: IO[bytes] | None = ..., bufsize: int = ..., format: int | None = ..., tarinfo: type[TarInfo] | None = ..., dereference: bool | None = ..., ignore_zeros: bool | None = ..., encoding: str | None = ..., errors: str = ..., pax_headers: Mapping[str, str] | None = ..., debug: int | None = ..., errorlevel: int | None = ..., preset: int | None = ...) -> TarFile
+ src/pip/_internal/utils/unpacking.py:179: note:     def open(name: str | bytes | PathLike[str] | PathLike[bytes] | Buffer | None = ..., *, mode: Literal['w|', 'w|gz', 'w|bz2', 'w|xz'], fileobj: IO[bytes] | None = ..., bufsize: int = ..., format: int | None = ..., tarinfo: type[TarInfo] | None = ..., dereference: bool | None = ..., ignore_zeros: bool | None = ..., encoding: str | None = ..., errors: str = ..., pax_headers: Mapping[str, str] | None = ..., debug: int | None = ..., errorlevel: int | None = ..., preset: int | None = ...) -> TarFile

[kbaikov]

@srittau could you please take a look at this PR? Not sure if i am forgetting an overload or not.

[srittau]

Why do you have an overload for name: StrOrBytesPath | None = None and name: StrOrBytesPath | None ?

This is a hack, since arguments without default can't follow arguments with default. For example, we need the overload with default so that open(mode="x") is accepted. On the other hand, the overload without default is used when calling open() positionally: open("foo.tar", "x"). In that case we can't use a default for name, because we can't have a default for mode. Ideally we would just have one overload, but that is a syntax error:

@overload
def open(
    name: StrOrBytesPath | None = None,
    mode: Literal["x", "x:", "a", "a:", "w", "w:"],
    fileobj: _Fileobj | None = None,
    ...
) -> TarFile: ...