filemerge: use non-minimal conflict marker regions (BC)

As extensively detailed by Pierre-Yves[1], simplemerge's minimal
markers can result in hopeless confusion for many common merges. As it
happens, we accidentally inherited this behavior when we borrowed
simplemerge from bzr; it is not the behavior used by RCS's merge(1),

Since merge(1) (and not bzr) is what we aim to emulate when emulating
RCS's merge markers, we simply turn this feature off. This brings us
in line with the behavior of CVS, SVN, and Git as a bonus.

(NB: using conflict markers with Mercurial is discouraged.)

[1] http://markmail.org/message/wj5mh3lc46czlvld

convert glob tessa

mercurial/filemerge.py

@@ -1,436 +1,436 b''
 # filemerge.py - file-level merge handling for Mercurial
 #
 # Copyright 2006, 2007, 2008 Matt Mackall <[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 node import short
 from i18n import _
 import util, simplemerge, match, error, templater, templatekw
 import os, tempfile, re, filecmp
 
 def _toolstr(ui, tool, part, default=""):
     return ui.config("merge-tools", tool + "." + part, default)
 
 def _toolbool(ui, tool, part, default=False):
     return ui.configbool("merge-tools", tool + "." + part, default)
 
 def _toollist(ui, tool, part, default=[]):
     return ui.configlist("merge-tools", tool + "." + part, default)
 
 internals = {}
 
 def internaltool(name, trymerge, onfailure=None):
     '''return a decorator for populating internal merge tool table'''
     def decorator(func):
         fullname = 'internal:' + name
         func.__doc__ = "``%s``\n" % fullname + func.__doc__.strip()
         internals[fullname] = func
         func.trymerge = trymerge
         func.onfailure = onfailure
         return func
     return decorator
 
 def _findtool(ui, tool):
     if tool in internals:
         return tool
     for kn in ("regkey", "regkeyalt"):
         k = _toolstr(ui, tool, kn)
         if not k:
             continue
         p = util.lookupreg(k, _toolstr(ui, tool, "regname"))
         if p:
             p = util.findexe(p + _toolstr(ui, tool, "regappend"))
             if p:
                 return p
     exe = _toolstr(ui, tool, "executable", tool)
     return util.findexe(util.expandpath(exe))
 
 def _picktool(repo, ui, path, binary, symlink):
     def check(tool, pat, symlink, binary):
         tmsg = tool
         if pat:
             tmsg += " specified for " + pat
         if not _findtool(ui, tool):
             if pat: # explicitly requested tool deserves a warning
                 ui.warn(_("couldn't find merge tool %s\n") % tmsg)
             else: # configured but non-existing tools are more silent
                 ui.note(_("couldn't find merge tool %s\n") % tmsg)
         elif symlink and not _toolbool(ui, tool, "symlink"):
             ui.warn(_("tool %s can't handle symlinks\n") % tmsg)
         elif binary and not _toolbool(ui, tool, "binary"):
             ui.warn(_("tool %s can't handle binary\n") % tmsg)
         elif not util.gui() and _toolbool(ui, tool, "gui"):
             ui.warn(_("tool %s requires a GUI\n") % tmsg)
         else:
             return True
         return False
 
     # forcemerge comes from command line arguments, highest priority
     force = ui.config('ui', 'forcemerge')
     if force:
         toolpath = _findtool(ui, force)
         if toolpath:
             return (force, util.shellquote(toolpath))
         else:
             # mimic HGMERGE if given tool not found
             return (force, force)
 
     # HGMERGE takes next precedence
     hgmerge = os.environ.get("HGMERGE")
     if hgmerge:
         return (hgmerge, hgmerge)
 
     # then patterns
     for pat, tool in ui.configitems("merge-patterns"):
         mf = match.match(repo.root, '', [pat])
         if mf(path) and check(tool, pat, symlink, False):
             toolpath = _findtool(ui, tool)
             return (tool, util.shellquote(toolpath))
 
     # then merge tools
     tools = {}
     for k, v in ui.configitems("merge-tools"):
         t = k.split('.')[0]
         if t not in tools:
             tools[t] = int(_toolstr(ui, t, "priority", "0"))
     names = tools.keys()
     tools = sorted([(-p, t) for t, p in tools.items()])
     uimerge = ui.config("ui", "merge")
     if uimerge:
         if uimerge not in names:
             return (uimerge, uimerge)
         tools.insert(0, (None, uimerge)) # highest priority
     tools.append((None, "hgmerge")) # the old default, if found
     for p, t in tools:
         if check(t, None, symlink, binary):
             toolpath = _findtool(ui, t)
             return (t, util.shellquote(toolpath))
 
     # internal merge or prompt as last resort
     if symlink or binary:
         return "internal:prompt", None
     return "internal:merge", None
 
 def _eoltype(data):
     "Guess the EOL type of a file"
     if '\0' in data: # binary
         return None
     if '\r\n' in data: # Windows
         return '\r\n'
     if '\r' in data: # Old Mac
         return '\r'
     if '\n' in data: # UNIX
         return '\n'
     return None # unknown
 
 def _matcheol(file, origfile):
     "Convert EOL markers in a file to match origfile"
     tostyle = _eoltype(util.readfile(origfile))
     if tostyle:
         data = util.readfile(file)
         style = _eoltype(data)
         if style:
             newdata = data.replace(style, tostyle)
             if newdata != data:
                 util.writefile(file, newdata)
 
 @internaltool('prompt', False)
 def _iprompt(repo, mynode, orig, fcd, fco, fca, toolconf):
     """Asks the user which of the local or the other version to keep as
     the merged version."""
     ui = repo.ui
     fd = fcd.path()
 
     if ui.promptchoice(_(" no tool found to merge %s\n"
                          "keep (l)ocal or take (o)ther?"
                          "$$ &Local $$ &Other") % fd, 0):
         return _iother(repo, mynode, orig, fcd, fco, fca, toolconf)
     else:
         return _ilocal(repo, mynode, orig, fcd, fco, fca, toolconf)
 
 @internaltool('local', False)
 def _ilocal(repo, mynode, orig, fcd, fco, fca, toolconf):
     """Uses the local version of files as the merged version."""
     return 0
 
 @internaltool('other', False)
 def _iother(repo, mynode, orig, fcd, fco, fca, toolconf):
     """Uses the other version of files as the merged version."""
     repo.wwrite(fcd.path(), fco.data(), fco.flags())
     return 0
 
 @internaltool('fail', False)
 def _ifail(repo, mynode, orig, fcd, fco, fca, toolconf):
     """
     Rather than attempting to merge files that were modified on both
     branches, it marks them as unresolved. The resolve command must be
     used to resolve these conflicts."""
     return 1
 
 def _premerge(repo, toolconf, files, labels=None):
     tool, toolpath, binary, symlink = toolconf
     if symlink:
         return 1
     a, b, c, back = files
 
     ui = repo.ui
 
     # do we attempt to simplemerge first?
     try:
         premerge = _toolbool(ui, tool, "premerge", not binary)
     except error.ConfigError:
         premerge = _toolstr(ui, tool, "premerge").lower()
         valid = 'keep'.split()
         if premerge not in valid:
             _valid = ', '.join(["'" + v + "'" for v in valid])
             raise error.ConfigError(_("%s.premerge not valid "
                                       "('%s' is neither boolean nor %s)") %
                                     (tool, premerge, _valid))
 
     if premerge:
         r = simplemerge.simplemerge(ui, a, b, c, quiet=True, label=labels)
         if not r:
             ui.debug(" premerge successful\n")
             return 0
         if premerge != 'keep':
             util.copyfile(back, a) # restore from backup and try again
     return 1 # continue merging
 
 @internaltool('merge', True,
               _("merging %s incomplete! "
                 "(edit conflicts, then use 'hg resolve --mark')\n"))
 def _imerge(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):
     """
     Uses the internal non-interactive simple merge algorithm for merging
     files. It will fail if there are any conflicts and leave markers in
     the partially merged file."""
     tool, toolpath, binary, symlink = toolconf
     if symlink:
         repo.ui.warn(_('warning: internal:merge cannot merge symlinks '
                        'for %s\n') % fcd.path())
         return False, 1
     r = _premerge(repo, toolconf, files, labels=labels)
     if r:
         a, b, c, back = files
 
         ui = repo.ui
 
-        r = simplemerge.simplemerge(ui, a, b, c, label=labels)
+        r = simplemerge.simplemerge(ui, a, b, c, label=labels, no_minimal=True)
         return True, r
     return False, 0
 
 @internaltool('dump', True)
 def _idump(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):
     """
     Creates three versions of the files to merge, containing the
     contents of local, other and base. These files can then be used to
     perform a merge manually. If the file to be merged is named
     ``a.txt``, these files will accordingly be named ``a.txt.local``,
     ``a.txt.other`` and ``a.txt.base`` and they will be placed in the
     same directory as ``a.txt``."""
     r = _premerge(repo, toolconf, files, labels=labels)
     if r:
         a, b, c, back = files
 
         fd = fcd.path()
 
         util.copyfile(a, a + ".local")
         repo.wwrite(fd + ".other", fco.data(), fco.flags())
         repo.wwrite(fd + ".base", fca.data(), fca.flags())
     return False, r
 
 def _xmerge(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):
     r = _premerge(repo, toolconf, files, labels=labels)
     if r:
         tool, toolpath, binary, symlink = toolconf
         a, b, c, back = files
         out = ""
         env = {'HG_FILE': fcd.path(),
                'HG_MY_NODE': short(mynode),
                'HG_OTHER_NODE': str(fco.changectx()),
                'HG_BASE_NODE': str(fca.changectx()),
                'HG_MY_ISLINK': 'l' in fcd.flags(),
                'HG_OTHER_ISLINK': 'l' in fco.flags(),
                'HG_BASE_ISLINK': 'l' in fca.flags(),
                }
 
         ui = repo.ui
 
         args = _toolstr(ui, tool, "args", '$local $base $other')
         if "$output" in args:
             out, a = a, back # read input from backup, write to original
         replace = {'local': a, 'base': b, 'other': c, 'output': out}
         args = util.interpolate(r'\$', replace, args,
                                 lambda s: util.shellquote(util.localpath(s)))
         r = util.system(toolpath + ' ' + args, cwd=repo.root, environ=env,
                         out=ui.fout)
         return True, r
     return False, 0
 
 def _formatconflictmarker(repo, ctx, template, label, pad):
     """Applies the given template to the ctx, prefixed by the label.
 
     Pad is the minimum width of the label prefix, so that multiple markers
     can have aligned templated parts.
     """
     if ctx.node() is None:
         ctx = ctx.p1()
 
     props = templatekw.keywords.copy()
     props['templ'] = template
     props['ctx'] = ctx
     props['repo'] = repo
     templateresult = template('conflictmarker', **props)
 
     label = ('%s:' % label).ljust(pad + 1)
     mark = '%s %s' % (label, templater.stringify(templateresult))
 
     if mark:
         mark = mark.splitlines()[0] # split for safety
 
     # 8 for the prefix of conflict marker lines (e.g. '<<<<<<< ')
     return util.ellipsis(mark, 80 - 8)
 
 _defaultconflictmarker = ('{node|short} ' +
     '{ifeq(tags, "tip", "", "{tags} ")}' +
     '{if(bookmarks, "{bookmarks} ")}' +
     '{ifeq(branch, "default", "", "{branch} ")}' +
     '- {author|user}: {desc|firstline}')
 
 _defaultconflictlabels = ['local', 'other']
 
 def _formatlabels(repo, fcd, fco, labels):
     """Formats the given labels using the conflict marker template.
 
     Returns a list of formatted labels.
     """
     cd = fcd.changectx()
     co = fco.changectx()
 
     ui = repo.ui
     template = ui.config('ui', 'mergemarkertemplate', _defaultconflictmarker)
     template = templater.parsestring(template, quoted=False)
     tmpl = templater.templater(None, cache={ 'conflictmarker' : template })
 
     pad = max(len(labels[0]), len(labels[1]))
 
     return [_formatconflictmarker(repo, cd, tmpl, labels[0], pad),
             _formatconflictmarker(repo, co, tmpl, labels[1], pad)]
 
 def filemerge(repo, mynode, orig, fcd, fco, fca, labels=None):
     """perform a 3-way merge in the working directory
 
     mynode = parent node before merge
     orig = original local filename before merge
     fco = other file context
     fca = ancestor file context
     fcd = local file context for current/destination file
     """
 
     def temp(prefix, ctx):
         pre = "%s~%s." % (os.path.basename(ctx.path()), prefix)
         (fd, name) = tempfile.mkstemp(prefix=pre)
         data = repo.wwritedata(ctx.path(), ctx.data())
         f = os.fdopen(fd, "wb")
         f.write(data)
         f.close()
         return name
 
     if not fco.cmp(fcd): # files identical?
         return None
 
     ui = repo.ui
     fd = fcd.path()
     binary = fcd.isbinary() or fco.isbinary() or fca.isbinary()
     symlink = 'l' in fcd.flags() + fco.flags()
     tool, toolpath = _picktool(repo, ui, fd, binary, symlink)
     ui.debug("picked tool '%s' for %s (binary %s symlink %s)\n" %
                (tool, fd, binary, symlink))
 
     if tool in internals:
         func = internals[tool]
         trymerge = func.trymerge
         onfailure = func.onfailure
     else:
         func = _xmerge
         trymerge = True
         onfailure = _("merging %s failed!\n")
 
     toolconf = tool, toolpath, binary, symlink
 
     if not trymerge:
         return func(repo, mynode, orig, fcd, fco, fca, toolconf)
 
     a = repo.wjoin(fd)
     b = temp("base", fca)
     c = temp("other", fco)
     back = a + ".orig"
     util.copyfile(a, back)
 
     if orig != fco.path():
         ui.status(_("merging %s and %s to %s\n") % (orig, fco.path(), fd))
     else:
         ui.status(_("merging %s\n") % fd)
 
     ui.debug("my %s other %s ancestor %s\n" % (fcd, fco, fca))
 
     markerstyle = ui.config('ui', 'mergemarkers', 'basic')
     if markerstyle == 'basic':
         formattedlabels = _defaultconflictlabels
     else:
         if not labels:
             labels = _defaultconflictlabels
 
         formattedlabels = _formatlabels(repo, fcd, fco, labels)
 
     needcheck, r = func(repo, mynode, orig, fcd, fco, fca, toolconf,
                         (a, b, c, back), labels=formattedlabels)
     if not needcheck:
         if r:
             if onfailure:
                 ui.warn(onfailure % fd)
         else:
             util.unlink(back)
 
         util.unlink(b)
         util.unlink(c)
         return r
 
     if not r and (_toolbool(ui, tool, "checkconflicts") or
                   'conflicts' in _toollist(ui, tool, "check")):
         if re.search("^(<<<<<<< .*|=======|>>>>>>> .*)$", fcd.data(),
                      re.MULTILINE):
             r = 1
 
     checked = False
     if 'prompt' in _toollist(ui, tool, "check"):
         checked = True
         if ui.promptchoice(_("was merge of '%s' successful (yn)?"
                              "$$ &Yes $$ &No") % fd, 1):
             r = 1
 
     if not r and not checked and (_toolbool(ui, tool, "checkchanged") or
                                   'changed' in _toollist(ui, tool, "check")):
         if filecmp.cmp(a, back):
             if ui.promptchoice(_(" output file %s appears unchanged\n"
                                  "was merge successful (yn)?"
                                  "$$ &Yes $$ &No") % fd, 1):
                 r = 1
 
     if _toolbool(ui, tool, "fixeol"):
         _matcheol(a, back)
 
     if r:
         if onfailure:
             ui.warn(onfailure % fd)
     else:
         util.unlink(back)
 
     util.unlink(b)
     util.unlink(c)
     return r
 
 # tell hggettext to extract docstrings from these functions:
 i18nfunctions = internals.values()

tests/test-conflict.t

@@ -1,185 +1,200 b''
   $ hg init
   $ cat << EOF > a
   > Small Mathematical Series.
   > One
   > Two
   > Three
   > Four
   > Five
   > Hop we are done.
   > EOF
   $ hg add a
   $ hg commit -m ancestor
   $ cat << EOF > a
   > Small Mathematical Series.
   > 1
   > 2
   > 3
   > 4
   > 5
   > Hop we are done.
   > EOF
   $ hg commit -m branch1
   $ hg co 0
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ cat << EOF > a
   > Small Mathematical Series.
   > 1
   > 2
   > 3
   > 6
   > 8
   > Hop we are done.
   > EOF
   $ hg commit -m branch2
   created new head
 
   $ hg merge 1
   merging a
   warning: conflicts during merge.
   merging a incomplete! (edit conflicts, then use 'hg resolve --mark')
   0 files updated, 0 files merged, 0 files removed, 1 files unresolved
   use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
   [1]
 
   $ hg id
   618808747361+c0c68e4fe667+ tip
 
   $ cat a
   Small Mathematical Series.
+  <<<<<<< local: 618808747361 - test: branch2
   1
   2
   3
-  <<<<<<< local: 618808747361 - test: branch2
   6
   8
   =======
+  1
+  2
+  3
   4
   5
   >>>>>>> other: c0c68e4fe667  - test: branch1
   Hop we are done.
 
   $ hg status
   M a
   ? a.orig
 
 Verify custom conflict markers
 
   $ hg up -q --clean .
   $ printf "\n[ui]\nmergemarkertemplate={author} {rev}\n" >> .hg/hgrc
 
   $ hg merge 1
   merging a
   warning: conflicts during merge.
   merging a incomplete! (edit conflicts, then use 'hg resolve --mark')
   0 files updated, 0 files merged, 0 files removed, 1 files unresolved
   use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
   [1]
 
   $ cat a
   Small Mathematical Series.
+  <<<<<<< local: test 2
   1
   2
   3
-  <<<<<<< local: test 2
   6
   8
   =======
+  1
+  2
+  3
   4
   5
   >>>>>>> other: test 1
   Hop we are done.
 
 Verify line splitting of custom conflict marker which causes multiple lines
 
   $ hg up -q --clean .
   $ cat >> .hg/hgrc <<EOF
   > [ui]
   > mergemarkertemplate={author} {rev}\nfoo\nbar\nbaz
   > EOF
 
   $ hg -q merge 1
   warning: conflicts during merge.
   merging a incomplete! (edit conflicts, then use 'hg resolve --mark')
   [1]
 
   $ cat a
   Small Mathematical Series.
+  <<<<<<< local: test 2
   1
   2
   3
-  <<<<<<< local: test 2
   6
   8
   =======
+  1
+  2
+  3
   4
   5
   >>>>>>> other: test 1
   Hop we are done.
 
 Verify line trimming of custom conflict marker using multi-byte characters
 
   $ hg up -q --clean .
   $ python <<EOF
   > fp = open('logfile', 'w')
   > fp.write('12345678901234567890123456789012345678901234567890' +
   >          '1234567890') # there are 5 more columns for 80 columns
   > 
   > # 2 x 4 = 8 columns, but 3 x 4 = 12 bytes
   > fp.write(u'\u3042\u3044\u3046\u3048'.encode('utf-8'))
   > 
   > fp.close()
   > EOF
   $ hg add logfile
   $ hg --encoding utf-8 commit --logfile logfile
 
   $ cat >> .hg/hgrc <<EOF
   > [ui]
   > mergemarkertemplate={desc|firstline}
   > EOF
 
   $ hg -q --encoding utf-8 merge 1
   warning: conflicts during merge.
   merging a incomplete! (edit conflicts, then use 'hg resolve --mark')
   [1]
 
   $ cat a
   Small Mathematical Series.
+  <<<<<<< local: 123456789012345678901234567890123456789012345678901234567890\xe3\x81\x82... (esc)
   1
   2
   3
-  <<<<<<< local: 123456789012345678901234567890123456789012345678901234567890\xe3\x81\x82... (esc)
   6
   8
   =======
+  1
+  2
+  3
   4
   5
   >>>>>>> other: branch1
   Hop we are done.
 
 Verify basic conflict markers
 
   $ hg up -q --clean 2
   $ printf "\n[ui]\nmergemarkers=basic\n" >> .hg/hgrc
 
   $ hg merge 1
   merging a
   warning: conflicts during merge.
   merging a incomplete! (edit conflicts, then use 'hg resolve --mark')
   0 files updated, 0 files merged, 0 files removed, 1 files unresolved
   use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
   [1]
 
   $ cat a
   Small Mathematical Series.
+  <<<<<<< local
   1
   2
   3
-  <<<<<<< local
   6
   8
   =======
+  1
+  2
+  3
   4
   5
   >>>>>>> other
   Hop we are done.