merge: expand environment variables and ~/ in tool.executable

hgrc(5) already implies that this works, so we might as well support it.

Another approach would be to implement this in util.findexe(): that
would benefit other callers of findexe(), e.g. convert and anyone
calling the user's editor. But findexe() is really implemented in
both posix.py and windows.py, so this would make both of those modules
depend on util.py: not good. So keep it narrow and only for merge
tools.

mercurial/filemerge.py

@@ -1,270 +1,271 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
 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)
 
 _internal = ['internal:' + s
              for s in 'fail local other merge prompt dump'.split()]
 
 def _findtool(ui, tool):
     if tool in _internal:
         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
-    return util.findexe(_toolstr(ui, tool, "executable", tool))
+    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, '"' + 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, '"' + 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, '"' + toolpath + '"')
     # internal merge as last resort
     return (not (symlink or binary) and "internal:merge" or None, 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)
 
 def filemerge(repo, mynode, orig, fcd, fco, fca):
     """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
 
     def isbin(ctx):
         try:
             return util.binary(ctx.data())
         except IOError:
             return False
 
     if not fco.cmp(fcd): # files identical?
         return None
 
     ui = repo.ui
     fd = fcd.path()
     binary = isbin(fcd) or isbin(fco) or isbin(fca)
     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 not tool or tool == 'internal:prompt':
         tool = "internal:local"
         if ui.promptchoice(_(" no tool found to merge %s\n"
                              "keep (l)ocal or take (o)ther?") % fd,
                            (_("&Local"), _("&Other")), 0):
             tool = "internal:other"
     if tool == "internal:local":
         return 0
     if tool == "internal:other":
         repo.wwrite(fd, fco.data(), fco.flags())
         return 0
     if tool == "internal:fail":
         return 1
 
     # do the actual merge
     a = repo.wjoin(fd)
     b = temp("base", fca)
     c = temp("other", fco)
     out = ""
     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))
 
     # do we attempt to simplemerge first?
     try:
         premerge = _toolbool(ui, tool, "premerge", not (binary or symlink))
     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)
         if not r:
             ui.debug(" premerge successful\n")
             os.unlink(back)
             os.unlink(b)
             os.unlink(c)
             return 0
         if premerge != 'keep':
             util.copyfile(back, a) # restore from backup and try again
 
     env = dict(HG_FILE=fd,
                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())
 
     if tool == "internal:merge":
         r = simplemerge.simplemerge(ui, a, b, c, label=['local', 'other'])
     elif tool == 'internal:dump':
         a = repo.wjoin(fd)
         util.copyfile(a, a + ".local")
         repo.wwrite(fd + ".other", fco.data(), fco.flags())
         repo.wwrite(fd + ".base", fca.data(), fca.flags())
         return 1 # unresolved
     else:
         args = _toolstr(ui, tool, "args", '$local $base $other')
         if "$output" in args:
             out, a = a, back # read input from backup, write to original
         replace = dict(local=a, base=b, other=c, output=out)
         args = util.interpolate(r'\$', replace, args,
                                 lambda s: '"%s"' % util.localpath(s))
         r = util.system(toolpath + ' ' + args, cwd=repo.root, environ=env,
                         out=ui.fout)
 
     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)?") % fd,
                            (_("&Yes"), _("&No")), 1):
             r = 1
 
     if not r and not checked and (_toolbool(ui, tool, "checkchanged") or
                                   'changed' in _toollist(ui, tool, "check")):
         if filecmp.cmp(repo.wjoin(fd), back):
             if ui.promptchoice(_(" output file %s appears unchanged\n"
                                  "was merge successful (yn)?") % fd,
                                (_("&Yes"), _("&No")), 1):
                 r = 1
 
     if _toolbool(ui, tool, "fixeol"):
         _matcheol(repo.wjoin(fd), back)
 
     if r:
         ui.warn(_("merging %s failed!\n") % fd)
     else:
         os.unlink(back)
 
     os.unlink(b)
     os.unlink(c)
     return r

tests/test-merge-tools.t

@@ -1,720 +1,744 b''
 test merge-tools configuration - mostly exercising filemerge.py
 
   $ unset HGMERGE # make sure HGMERGE doesn't interfere with the test
   $ hg init
 
 revision 0
 
   $ echo "revision 0" > f
   $ echo "space" >> f
   $ hg commit -Am "revision 0"
   adding f
 
 revision 1
 
   $ echo "revision 1" > f
   $ echo "space" >> f
   $ hg commit -Am "revision 1"
   $ hg update 0 > /dev/null
 
 revision 2
 
   $ echo "revision 2" > f
   $ echo "space" >> f
   $ hg commit -Am "revision 2"
   created new head
   $ hg update 0 > /dev/null
 
 revision 3 - simple to merge
 
   $ echo "revision 3" >> f
   $ hg commit -Am "revision 3"
   created new head
   $ echo "[merge-tools]" > .hg/hgrc
 
   $ beforemerge() {
   >   cat .hg/hgrc
   >   echo "# hg update -C 1"
   >   hg update -C 1 > /dev/null
   > }
   $ aftermerge() {
   >   echo "# cat f"
   >   cat f
   >   echo "# hg stat"
   >   hg stat
   >   rm -f f.orig
   > }
   $ domerge() {
   >   beforemerge
   >   echo "# hg merge $*"
   >   hg merge $*
   >   aftermerge
   > }
 
 Tool selection
 
 default is internal merge:
 
   $ beforemerge
   [merge-tools]
   # hg update -C 1
 
 hg merge -r 2
 override $PATH to ensure hgmerge not visible; use $PYTHON in case we're
 running from a devel copy, not a temp installation
 
   $ PATH="$BINDIR" $PYTHON "$BINDIR"/hg merge -r 2
   merging f
   warning: conflicts during merge.
   merging f failed!
   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]
   $ aftermerge
   # cat f
   <<<<<<< local
   revision 1
   =======
   revision 2
   >>>>>>> other
   space
   # hg stat
   M f
   ? f.orig
 
 simplest hgrc using false for merge:
 
   $ echo "false.whatever=" >> .hg/hgrc
   $ domerge -r 2
   [merge-tools]
   false.whatever=
   # hg update -C 1
   # hg merge -r 2
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 true with higher .priority gets precedence:
 
   $ echo "true.priority=1" >> .hg/hgrc
   $ domerge -r 2
   [merge-tools]
   false.whatever=
   true.priority=1
   # hg update -C 1
   # hg merge -r 2
   merging f
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   # cat f
   revision 1
   space
   # hg stat
   M f
 
 unless lowered on command line:
 
   $ domerge -r 2 --config merge-tools.true.priority=-7
   [merge-tools]
   false.whatever=
   true.priority=1
   # hg update -C 1
   # hg merge -r 2 --config merge-tools.true.priority=-7
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 or false set higher on command line:
 
   $ domerge -r 2 --config merge-tools.false.priority=117
   [merge-tools]
   false.whatever=
   true.priority=1
   # hg update -C 1
   # hg merge -r 2 --config merge-tools.false.priority=117
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 or true.executable not found in PATH:
 
   $ domerge -r 2 --config merge-tools.true.executable=nonexistingmergetool
   [merge-tools]
   false.whatever=
   true.priority=1
   # hg update -C 1
   # hg merge -r 2 --config merge-tools.true.executable=nonexistingmergetool
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 or true.executable with bogus path:
 
   $ domerge -r 2 --config merge-tools.true.executable=/nonexisting/mergetool
   [merge-tools]
   false.whatever=
   true.priority=1
   # hg update -C 1
   # hg merge -r 2 --config merge-tools.true.executable=/nonexisting/mergetool
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 but true.executable set to cat found in PATH works:
 
   $ echo "true.executable=cat" >> .hg/hgrc
   $ domerge -r 2
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2
   merging f
   revision 1
   space
   revision 0
   space
   revision 2
   space
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   # cat f
   revision 1
   space
   # hg stat
   M f
 
 and true.executable set to cat with path works:
 
   $ domerge -r 2 --config merge-tools.true.executable=cat
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config merge-tools.true.executable=cat
   merging f
   revision 1
   space
   revision 0
   space
   revision 2
   space
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   # cat f
   revision 1
   space
   # hg stat
   M f
 
+environment variables in true.executable are handled:
+
+  $ cat > $HGTMP/merge.sh <<EOF
+  > #!/bin/sh
+  > echo 'custom merge tool'
+  > EOF
+  $ chmod +x $HGTMP/merge.sh
+  $ domerge -r 2 --config merge-tools.true.executable='$HGTMP/merge.sh'
+  [merge-tools]
+  false.whatever=
+  true.priority=1
+  true.executable=cat
+  # hg update -C 1
+  # hg merge -r 2 --config merge-tools.true.executable=$HGTMP/merge.sh
+  merging f
+  custom merge tool
+  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  # cat f
+  revision 1
+  space
+  # hg stat
+  M f
+
 Tool selection and merge-patterns
 
 merge-patterns specifies new tool false:
 
   $ domerge -r 2 --config merge-patterns.f=false
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config merge-patterns.f=false
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 merge-patterns specifies executable not found in PATH and gets warning:
 
   $ domerge -r 2 --config merge-patterns.f=true --config merge-tools.true.executable=nonexistingmergetool
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config merge-patterns.f=true --config merge-tools.true.executable=nonexistingmergetool
   couldn't find merge tool true specified for f
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 merge-patterns specifies executable with bogus path and gets warning:
 
   $ domerge -r 2 --config merge-patterns.f=true --config merge-tools.true.executable=/nonexisting/mergetool
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config merge-patterns.f=true --config merge-tools.true.executable=/nonexisting/mergetool
   couldn't find merge tool true specified for f
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 ui.merge overrules priority
 
 ui.merge specifies false:
 
   $ domerge -r 2 --config ui.merge=false
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config ui.merge=false
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 ui.merge specifies internal:fail:
 
   $ domerge -r 2 --config ui.merge=internal:fail
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config ui.merge=internal:fail
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
 
 ui.merge specifies internal:local:
 
   $ domerge -r 2 --config ui.merge=internal:local
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config ui.merge=internal:local
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   # cat f
   revision 1
   space
   # hg stat
   M f
 
 ui.merge specifies internal:other:
 
   $ domerge -r 2 --config ui.merge=internal:other
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config ui.merge=internal:other
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   # cat f
   revision 2
   space
   # hg stat
   M f
 
 ui.merge specifies internal:prompt:
 
   $ domerge -r 2 --config ui.merge=internal:prompt
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config ui.merge=internal:prompt
    no tool found to merge f
   keep (l)ocal or take (o)ther? l
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   # cat f
   revision 1
   space
   # hg stat
   M f
 
 ui.merge specifies internal:dump:
 
   $ domerge -r 2 --config ui.merge=internal:dump
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config ui.merge=internal:dump
   merging f
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.base
   ? f.local
   ? f.orig
   ? f.other
 
 f.base:
 
   $ cat f.base
   revision 0
   space
 
 f.local:
 
   $ cat f.local
   revision 1
   space
 
 f.other:
 
   $ cat f.other
   revision 2
   space
   $ rm f.base f.local f.other
 
 ui.merge specifies internal:other but is overruled by pattern for false:
 
   $ domerge -r 2 --config ui.merge=internal:other --config merge-patterns.f=false
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config ui.merge=internal:other --config merge-patterns.f=false
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 Premerge
 
 ui.merge specifies internal:other but is overruled by --tool=false
 
   $ domerge -r 2 --config ui.merge=internal:other --tool=false
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --config ui.merge=internal:other --tool=false
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
 HGMERGE specifies internal:other but is overruled by --tool=false
 
   $ HGMERGE=internal:other ; export HGMERGE
   $ domerge -r 2 --tool=false
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 2 --tool=false
   merging f
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig
 
   $ unset HGMERGE # make sure HGMERGE doesn't interfere with remaining tests
 
 Default is silent simplemerge:
 
   $ domerge -r 3
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 3
   merging f
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   # cat f
   revision 1
   space
   revision 3
   # hg stat
   M f
 
 .premerge=True is same:
 
   $ domerge -r 3 --config merge-tools.true.premerge=True
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 3 --config merge-tools.true.premerge=True
   merging f
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   # cat f
   revision 1
   space
   revision 3
   # hg stat
   M f
 
 .premerge=False executes merge-tool:
 
   $ domerge -r 3 --config merge-tools.true.premerge=False
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -r 3 --config merge-tools.true.premerge=False
   merging f
   revision 1
   space
   revision 0
   space
   revision 0
   space
   revision 3
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   # cat f
   revision 1
   space
   # hg stat
   M f
 
 Tool execution
 
 set tools.args explicit to include $base $local $other $output:
 
   $ beforemerge
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   $ hg merge -r 2 --config merge-tools.true.executable=head --config merge-tools.true.args='$base $local $other $output' \
   >   | sed 's,==> .* <==,==> ... <==,g'
   merging f
   ==> ... <==
   revision 0
   space
   
   ==> ... <==
   revision 1
   space
   
   ==> ... <==
   revision 2
   space
   
   ==> ... <==
   revision 1
   space
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ aftermerge
   # cat f
   revision 1
   space
   # hg stat
   M f
 
 Merge with "echo mergeresult > $local":
 
   $ beforemerge
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   $ hg merge -r 2 --config merge-tools.true.executable=echo --config merge-tools.true.args='mergeresult > $local'
   merging f
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ aftermerge
   # cat f
   mergeresult
   # hg stat
   M f
 
 - and $local is the file f:
 
   $ beforemerge
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   $ hg merge -r 2 --config merge-tools.true.executable=echo --config merge-tools.true.args='mergeresult > f'
   merging f
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ aftermerge
   # cat f
   mergeresult
   # hg stat
   M f
 
 Merge with "echo mergeresult > $output" - the variable is a bit magic:
 
   $ beforemerge
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   $ hg merge -r 2 --config merge-tools.true.executable=echo --config merge-tools.true.args='mergeresult > $output'
   merging f
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ aftermerge
   # cat f
   mergeresult
   # hg stat
   M f
 
 Merge using tool with a path that must be quoted:
 
   $ beforemerge
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   $ cat <<EOF > 'my merge tool'
   > #!/bin/sh
   > cat "\$1" "\$2" "\$3" > "\$4"
   > EOF
   $ chmod +x 'my merge tool'
   $ hg merge -r 2 --config merge-tools.true.executable='./my merge tool' --config merge-tools.true.args='$base $local $other $output'
   merging f
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ rm -f 'my merge tool'
   $ aftermerge
   # cat f
   revision 0
   space
   revision 1
   space
   revision 2
   space
   # hg stat
   M f
 
 Merge post-processing
 
 cat is a bad merge-tool and doesn't change:
 
   $ domerge -y -r 2 --config merge-tools.true.checkchanged=1
   [merge-tools]
   false.whatever=
   true.priority=1
   true.executable=cat
   # hg update -C 1
   # hg merge -y -r 2 --config merge-tools.true.checkchanged=1
   merging f
   revision 1
   space
   revision 0
   space
   revision 2
   space
    output file f appears unchanged
   was merge successful (yn)? n
   merging f failed!
   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
   # cat f
   revision 1
   space
   # hg stat
   M f
   ? f.orig