view mercurial/policy.py @ 32255:7e35d31b41fd

filemerge: add internal merge tool to dump files forcibly

Internal merge tool :dump implies premerge. Therefore, files aren't
dumped, if premerge runs successfully.

This undocumented behavior might confuse users, if they want to always
dump files. But just making :dump omit premerge might cause backward
compatibility issue for existing automation.

This patch adds new internal merge tool :forcedump, which works as
same as :dump, but omits premerge always.

Internal tools annotated with "nomerge" should merge "change and
delete" correctly, but _forcedump() can't. Therefore, it is annotated
with "mergeonly" to always omit premerge, even though it doesn't merge
files actually.

This patch also adds explanation about premerge to :dump, to clarify
how :dump actually works.

BTW, this patch specifies internal tools with "internal:" prefix in
newly added test scenario in test-merge-tools.t, even though this
prefix is already deprecated. This is only for similarity to other
tests in test-merge-tools.t.

# policy.py - module policy logic for Mercurial.
#
# Copyright 2015 Gregory Szorc <[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.

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'
policynoc = (b'cffi', b'cffi-allow', b'py')
policynocffi = (b'c', b'py')

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)