view mercurial/typelib.py @ 51833:6388fd855f66 stable

setup: handle removal of old MSVC compiler from setuptools 65.0 (issue6910)

It was removed a few years ago[1].  When trying to reproduce locally using a
clean py3.12 as called out in the bug report, `setuptools` wasn't installed at
all, and needed a `pip install` to fix a `ModuleNotFoundError` when building
locally.  Maybe that needs to be in the requirements clause now.

It looks like this "private" module was added in setuptools 48.0.[2]  I can't
find a changelog of what version was included in which version of python, and
the changelog for pip has a huge gap between when it called out 67.6.1 in `pip`
23.1 (2023-04-15), and 41.4.0 in `pip` 19.3 (2019-10-14).[3]  So, we'll just add
to the existing code instead of replacing it, for safety.

[1] https://github.com/pypa/setuptools/commit/cc017c77948737d131f683e0c25cd37bc639b8fc
[2] https://github.com/pypa/setuptools/commit/d034a5ec7f707499139f90eb846b9e720923124c
[3] https://pip.pypa.io/en/stable/news/

# typelib.py - type hint aliases and support
#
# Copyright 2022 Matt Harbison <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

import typing

# Note: this is slightly different from pycompat.TYPE_CHECKING, as using
# pycompat causes the BinaryIO_Proxy type to be resolved to ``object`` when
# used as the base class during a pytype run.
TYPE_CHECKING = typing.TYPE_CHECKING


# The BinaryIO class provides empty methods, which at runtime means that
# ``__getattr__`` on the proxy classes won't get called for the methods that
# should delegate to the internal object.  So to avoid runtime changes because
# of the required typing inheritance, just use BinaryIO when typechecking, and
# ``object`` otherwise.
if TYPE_CHECKING:
    from typing import (
        BinaryIO,
    )

    BinaryIO_Proxy = BinaryIO
else:
    BinaryIO_Proxy = object