hgdemandimport/__init__.py

setup: drop legacy osx compiler tuning to enable universal builds

This was triggering deprecation warnings about migrating to `packaging.version`
from `distutils` Version classes with `make local`.  But rather than migrate
that code, let's just get rid of some ~10-12 year old workarounds.  As a bonus,
the cext libraries that are built are now universal binaries containing x86_64
and arm64 images (at least when built on macOS 11.4 with Xcode 12.5 and the
universal version of Python 3.9.13).

Several things to note here:

   - Apple dropped support for 10.15 in Nov 2022, and OS X Lion that is
     referenced is 10.7 (unsupported since late 2014)
   - `xcode4` was basically always True because of the `>=` check (10.8 used
     Xcode 5, and I have Xcode 10.2 on 10.14)
   - `xcode51` was always False for modern-ish Xcode, because of the exact
     version string matching
   - Python 3.8 only supports OS X 10.9+; the Python 3.9.1+ universal installer
     is macOS 11+ only, and Python 3.10 drops the x86_64 installer to deliver
     only the universal installer.

All of this is to say, the only thing lost by dropping this code on modern Xcode
is that `os.environ['ARCHFLAGS'] = ''` is no longer set.  But we probably
shouldn't be setting that anymore, as shown by the universal libraries now being
generated.  I was able to `make local` and `python3 run-tests.py --local` with
python 3.9.9, Xcode 10.2, and macOS 10.14.6, and didn't incur any more than the
usual few test errors, so this should still work on some older versions of
macOS.

# hgdemandimport - global demand-loading of modules for Mercurial
#
# Copyright 2017 Facebook Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''demandimport - automatic demand-loading of modules'''

# This is in a separate package from mercurial because in Python 3,
# demand loading is per-package. Keeping demandimport in the mercurial package
# would disable demand loading for any modules in mercurial.


import os
import sys

from . import demandimportpy3 as demandimport

# Full module names which can't be lazy imported.
# Extensions can add to this set.
IGNORES = {
    '__future__',
    '_hashlib',
    # ImportError during pkg_resources/__init__.py:fixup_namespace_package
    '_imp',
    '_xmlplus',
    'fcntl',
    'nt',  # pathlib2 tests the existence of built-in 'nt' module
    'win32com.gen_py',
    'win32com.shell',  # 'appdirs' tries to import win32com.shell
    '_winreg',  # 2.7 mimetypes needs immediate ImportError
    'pythoncom',
    # imported by tarfile, not available under Windows
    'pwd',
    'grp',
    # imported by profile, itself imported by hotshot.stats,
    # not available under Windows
    'resource',
    # this trips up many extension authors
    'gtk',
    # setuptools' pkg_resources.py expects "from __main__ import x" to
    # raise ImportError if x not defined
    '__main__',
    '_ast',  # https://bugs.python.org/issue41631
    '_ssl',  # conditional imports in the stdlib, issue1964
    '_sre',  # issue4920
    'rfc822',
    'mimetools',
    'sqlalchemy.events',  # has import-time side effects (issue5085)
    'sqlalchemy.dialects',  # similar problems as above
    # setuptools 8 expects this module to explode early when not on windows
    'distutils.msvc9compiler',
    '__builtin__',
    'builtins',
    'urwid.command_map',  # for pudb
    'lzma',
}

_pypy = '__pypy__' in sys.builtin_module_names

if _pypy:
    # _ctypes.pointer is shadowed by "from ... import pointer" (PyPy 5)
    IGNORES.add('_ctypes.pointer')
    # pure Python module on PyPy, must be loaded to raise ModuleNotFoundError
    # on non-Windows platforms
    IGNORES.add('msvcrt')

demandimport.init(IGNORES)

# Re-export.
isenabled = demandimport.isenabled
disable = demandimport.disable
deactivated = demandimport.deactivated


def enable():
    # chg pre-imports modules so do not enable demandimport for it
    if (
        'CHGINTERNALMARK' not in os.environ
        and os.environ.get('HGDEMANDIMPORT') != 'disable'
    ):
        demandimport.enable()