mercurial/diffutil.py

copies: choose target directory based on longest match

If one side of a merge renames `dir1/` to `dir2/` and the subdirectory
`dir1/subdir1/` to `dir2/subdir2/`, and the other side of the merge
adds a file in `dir1/subdir1/`, we should clearly move that into
`dir2/subdir2/`. We already detect the directories correctly before
this patch, but we iterate over them in arbitrary order. That results
in the new file sometimes ending up in `dir2/subdir1/` instead. This
patch fixes it by iterating over the source directories by visiting
subdirectories first. That's achieved by simply iterating over them in
reverse lexicographical order.

Without the fix, the test case still passes on Python 2 but fails on
Python 3. It depends on the iteration order of the dict. I did not
look into how it's built up and why it behaved differently before the
fix. I could probably have gotten it to fail on Python 2 as well by
choosing different directory names.

Differential Revision: https://phab.mercurial-scm.org/D10115

# diffutil.py - utility functions related to diff and patch
#
# Copyright 2006 Brendan Cully <[e-mail]>
# Copyright 2007 Chris Mason <[e-mail]>
# Copyright 2018 Octobus <[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

from .i18n import _

from . import (
    mdiff,
    pycompat,
)


def diffallopts(
    ui, opts=None, untrusted=False, section=b'diff', configprefix=b''
):
    '''return diffopts with all features supported and parsed'''
    return difffeatureopts(
        ui,
        opts=opts,
        untrusted=untrusted,
        section=section,
        git=True,
        whitespace=True,
        formatchanging=True,
        configprefix=configprefix,
    )


def difffeatureopts(
    ui,
    opts=None,
    untrusted=False,
    section=b'diff',
    git=False,
    whitespace=False,
    formatchanging=False,
    configprefix=b'',
):
    """return diffopts with only opted-in features parsed

    Features:
    - git: git-style diffs
    - whitespace: whitespace options like ignoreblanklines and ignorews
    - formatchanging: options that will likely break or cause correctness issues
      with most diff parsers
    """

    def get(key, name=None, getter=ui.configbool, forceplain=None):
        if opts:
            v = opts.get(key)
            # diffopts flags are either None-default (which is passed
            # through unchanged, so we can identify unset values), or
            # some other falsey default (eg --unified, which defaults
            # to an empty string). We only want to override the config
            # entries from hgrc with command line values if they
            # appear to have been set, which is any truthy value,
            # True, or False.
            if v or isinstance(v, bool):
                return v
        if forceplain is not None and ui.plain():
            return forceplain
        return getter(
            section, configprefix + (name or key), untrusted=untrusted
        )

    # core options, expected to be understood by every diff parser
    buildopts = {
        b'nodates': get(b'nodates'),
        b'showfunc': get(b'show_function', b'showfunc'),
        b'context': get(b'unified', getter=ui.config),
    }
    buildopts[b'xdiff'] = ui.configbool(b'experimental', b'xdiff')

    if git:
        buildopts[b'git'] = get(b'git')

        # since this is in the experimental section, we need to call
        # ui.configbool directory
        buildopts[b'showsimilarity'] = ui.configbool(
            b'experimental', b'extendedheader.similarity'
        )

        # need to inspect the ui object instead of using get() since we want to
        # test for an int
        hconf = ui.config(b'experimental', b'extendedheader.index')
        if hconf is not None:
            hlen = None
            try:
                # the hash config could be an integer (for length of hash) or a
                # word (e.g. short, full, none)
                hlen = int(hconf)
                if hlen < 0 or hlen > 40:
                    msg = _(b"invalid length for extendedheader.index: '%d'\n")
                    ui.warn(msg % hlen)
            except ValueError:
                # default value
                if hconf == b'short' or hconf == b'':
                    hlen = 12
                elif hconf == b'full':
                    hlen = 40
                elif hconf != b'none':
                    msg = _(b"invalid value for extendedheader.index: '%s'\n")
                    ui.warn(msg % hconf)
            finally:
                buildopts[b'index'] = hlen

    if whitespace:
        buildopts[b'ignorews'] = get(b'ignore_all_space', b'ignorews')
        buildopts[b'ignorewsamount'] = get(
            b'ignore_space_change', b'ignorewsamount'
        )
        buildopts[b'ignoreblanklines'] = get(
            b'ignore_blank_lines', b'ignoreblanklines'
        )
        buildopts[b'ignorewseol'] = get(b'ignore_space_at_eol', b'ignorewseol')
    if formatchanging:
        buildopts[b'text'] = opts and opts.get(b'text')
        binary = None if opts is None else opts.get(b'binary')
        buildopts[b'nobinary'] = (
            not binary
            if binary is not None
            else get(b'nobinary', forceplain=False)
        )
        buildopts[b'noprefix'] = get(b'noprefix', forceplain=False)
        buildopts[b'worddiff'] = get(
            b'word_diff', b'word-diff', forceplain=False
        )

    return mdiff.diffopts(**pycompat.strkwargs(buildopts))