setup: avoid linker warnings on Windows about multiple export specifications
The PyMODINIT_FUNC macro contains __declspec(dllexport), and then the build
process adds an "/EXPORT func" to the command line. The 64-bit linker flags
this [1].
Everything except zstd.c and bser.c are covered by redefining the macro in
util.h [2]. These modules aren't built with util.h in the #include path, so the
redefining hack would have to be open coded two more times.
After seeing that extra_linker_flags didn't work, I couldn't find anything
authoritative indicating why, though I did see an offhand comment on SO that
CFLAGS is also ignored on Windows. I also don't fully understand the
interaction between msvccompiler and msvc9compiler- I first subclassed the
latter, but it isn't used when building with VS2008.
I know the camelcase naming isn't the standard, but the HackedMingw32CCompiler
class above it was introduced 5 years ago (and I think the current style was
in place by then), so I assume that there's some reason for it.
[1] https://support.microsoft.com/en-us/help/835326/you-receive-an-lnk4197-error-in-the-64-bit-version-of-the-visual-c-compiler
[2] https://bugs.python.org/issue9709#msg120859
# policy.py - module policy logic for Mercurial.
#
# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import os
import sys
# Rules for how modules can be loaded. Values are:
#
# c - require C extensions
# allow - allow pure Python implementation when C loading fails
# cffi - required cffi versions (implemented within pure module)
# cffi-allow - allow pure Python implementation if cffi version is missing
# py - only load pure Python modules
#
# By default, fall back to the pure modules so the in-place build can
# run without recompiling the C extensions. This will be overridden by
# __modulepolicy__ generated by setup.py.
policy = b'allow'
_packageprefs = {
# policy: (versioned package, pure package)
b'c': (r'cext', None),
b'allow': (r'cext', r'pure'),
b'cffi': (r'cffi', None),
b'cffi-allow': (r'cffi', r'pure'),
b'py': (None, r'pure'),
}
try:
from . import __modulepolicy__
policy = __modulepolicy__.modulepolicy
except ImportError:
pass
# PyPy doesn't load C extensions.
#
# The canonical way to do this is to test platform.python_implementation().
# But we don't import platform and don't bloat for it here.
if r'__pypy__' in sys.builtin_module_names:
policy = b'cffi'
# Our C extensions aren't yet compatible with Python 3. So use pure Python
# on Python 3 for now.
if sys.version_info[0] >= 3:
policy = b'py'
# Environment variable can always force settings.
if sys.version_info[0] >= 3:
if r'HGMODULEPOLICY' in os.environ:
policy = os.environ[r'HGMODULEPOLICY'].encode(r'utf-8')
else:
policy = os.environ.get(r'HGMODULEPOLICY', policy)
def _importfrom(pkgname, modname):
# from .<pkgname> import <modname> (where . is looked through this module)
fakelocals = {}
pkg = __import__(pkgname, globals(), fakelocals, [modname], level=1)
try:
fakelocals[modname] = mod = getattr(pkg, modname)
except AttributeError:
raise ImportError(r'cannot import name %s' % modname)
# force import; fakelocals[modname] may be replaced with the real module
getattr(mod, r'__doc__', None)
return fakelocals[modname]
# keep in sync with "version" in C modules
_cextversions = {
(r'cext', r'base85'): 1,
(r'cext', r'bdiff'): 1,
(r'cext', r'diffhelpers'): 1,
(r'cext', r'mpatch'): 1,
(r'cext', r'osutil'): 1,
(r'cext', r'parsers'): 1,
}
def _checkmod(pkgname, modname, mod):
expected = _cextversions.get((pkgname, modname))
actual = getattr(mod, r'version', None)
if actual != expected:
raise ImportError(r'cannot import module %s.%s '
r'(expected version: %d, actual: %r)'
% (pkgname, modname, expected, actual))
def importmod(modname):
"""Import module according to policy and check API version"""
try:
verpkg, purepkg = _packageprefs[policy]
except KeyError:
raise ImportError(r'invalid HGMODULEPOLICY %r' % policy)
assert verpkg or purepkg
if verpkg:
try:
mod = _importfrom(verpkg, modname)
_checkmod(verpkg, modname, mod)
return mod
except ImportError:
if not purepkg:
raise
return _importfrom(purepkg, modname)