D2889: filemerge: make the 'local' path match the format that 'base' and 'other' use

[spectral (Kyle Lippincott)]

spectral created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  If we pass a separate '$output' arg to the merge tool, we produce four files:
  local, base, other, and output.  In this situation, 'output' will be the
  original filename, 'base' and 'other' are temporary files, and previously
  'local' would be the backup file (so if 'output' was foo.txt, 'local' would be
  foo.txt.orig).
  
  This change makes it so that 'local' follows the same pattern as 'base' and
  'other' - it will be a temporary file either in the
  `experimental.mergetempdirprefix`-controlled directory with a name like
  foo~local.txt, or in the normal system-wide temp dir with a name like
  foo~local.RaNd0m.txt.
  
  For the cases where the merge tool does not use an '$output' arg, 'local' is
  still the destination filename, and 'base' and 'other' are unchanged.
  
  The hope is that this is much easier for people to reason about; rather than
  having a tool like Meld pop up with three panes, one of them with the filename
  "foo.txt.orig", one with the filename "foo.txt", and one with
  "foo~other.StuFf2.txt", we can (when the merge temp dir stuff is enabled) make
  it show up as "foo~local.txt", "foo.txt" and "foo~other.txt", respectively.
  
  This also opens the door to future customization, such as getting the
  operation-provided labels and a hash prefix into the filenames (so we see
  something like "foo~dest.abc123", "foo.txt", and "foo~src.d4e5f6").

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2889

AFFECTED FILES
  mercurial/filemerge.py
  tests/test-merge-tools.t

CHANGE DETAILS

diff --git a/tests/test-merge-tools.t b/tests/test-merge-tools.t
--- a/tests/test-merge-tools.t
+++ b/tests/test-merge-tools.t
@@ -1585,7 +1585,7 @@
   $ hg update -q -C 2
   $ hg merge -y -r tip --tool echo --config merge-tools.echo.args='$base $local $other $output'
   merging f and f.txt to f.txt
-  */f~base.?????? $TESTTMP/f.txt.orig */f~other.??????.txt $TESTTMP/f.txt (glob)
+  */f~base.?????? */f~local.??????.txt */f~other.??????.txt $TESTTMP/f.txt (glob)
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
@@ -1600,7 +1600,7 @@
   >    --config merge-tools.echo.args='$base $local $other $output' \
   >    --config experimental.mergetempdirprefix=$TESTTMP/hgmerge.
   merging f and f.txt to f.txt
-  $TESTTMP/hgmerge.??????/f~base $TESTTMP/f.txt.orig $TESTTMP/hgmerge.??????/f~other.txt $TESTTMP/f.txt (glob)
+  $TESTTMP/hgmerge.??????/f~base $TESTTMP/hgmerge.??????/f~local.txt $TESTTMP/hgmerge.??????/f~other.txt $TESTTMP/f.txt (glob)
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 Check that debugpicktool examines which merge tool is chosen for
diff --git a/mercurial/filemerge.py b/mercurial/filemerge.py
--- a/mercurial/filemerge.py
+++ b/mercurial/filemerge.py
@@ -512,8 +512,11 @@
         return False, 1, None
     unused, unused, unused, back = files
     localpath = _workingpath(repo, fcd)
-    with _maketempfiles(repo, fco, fca) as temppaths:
-        basepath, otherpath = temppaths
+    args = _toolstr(repo.ui, tool, "args")
+
+    with _maketempfiles(repo, fco, fca, repo.wvfs.join(back.path()),
+                        "$output" in args) as temppaths:
+        basepath, otherpath, localoutputpath = temppaths
         outpath = ""
         mylabel, otherlabel = labels[:2]
         if len(labels) >= 3:
@@ -533,11 +536,10 @@
                }
         ui = repo.ui
 
-        args = _toolstr(ui, tool, "args")
         if "$output" in args:
             # read input from backup, write to original
             outpath = localpath
-            localpath = repo.wvfs.join(back.path())
+            localpath = localoutputpath
         replace = {'local': localpath, 'base': basepath, 'other': otherpath,
                    'output': outpath, 'labellocal': mylabel,
                    'labelother': otherlabel, 'labelbase': baselabel}
@@ -665,41 +667,59 @@
         return context.arbitraryfilectx(back, repo=repo)
 
 @contextlib.contextmanager
-def _maketempfiles(repo, fco, fca):
-    """Writes out `fco` and `fca` as temporary files, so an external merge
-    tool may use them.
+def _maketempfiles(repo, fco, fca, localpath, uselocalpath):
+    """Writes out `fco` and `fca` as temporary files, and (if not None) copies
+    `localpath` to another temporary file, so an external merge tool may use
+    them.
     """
     tmproot = None
     tmprootprefix = repo.ui.config('experimental', 'mergetempdirprefix')
     if tmprootprefix:
         tmproot = tempfile.mkdtemp(prefix=tmprootprefix)
 
-    def temp(prefix, ctx):
-        fullbase, ext = os.path.splitext(ctx.path())
+    def maketempfrompath(prefix, path):
+        fullbase, ext = os.path.splitext(path)
         pre = "%s~%s" % (os.path.basename(fullbase), prefix)
         if tmproot:
             name = os.path.join(tmproot, pre)
             if ext:
                 name += ext
             f = open(name, r"wb")
         else:
-            (fd, name) = tempfile.mkstemp(prefix=pre + '.', suffix=ext)
+            fd, name = tempfile.mkstemp(prefix=pre + '.', suffix=ext)
             f = os.fdopen(fd, r"wb")
+        return f, name
+
+    def tempfromcontext(prefix, ctx):
+        f, name = maketempfrompath(prefix, ctx.path())
         data = repo.wwritedata(ctx.path(), ctx.data())
         f.write(data)
         f.close()
         return name
 
-    b = temp("base", fca)
-    c = temp("other", fco)
+    b = tempfromcontext("base", fca)
+    c = tempfromcontext("other", fco)
+    d = localpath
+    if uselocalpath:
+        if d.endswith('.orig'):
+            d, _ = os.path.splitext(d)
+        f, d = maketempfrompath("local", d)
+        with open(localpath, 'rb') as src:
+            f.write(src.read())
+        f.close()
+
     try:
-        yield b, c
+        yield b, c, d
     finally:
         if tmproot:
             shutil.rmtree(tmproot)
         else:
             util.unlink(b)
             util.unlink(c)
+            # if not uselocalpath, d is the 'orig'/backup file which we
+            # shouldn't delete.
+            if d and uselocalpath:
+                util.unlink(d)
 
 def _filemerge(premerge, repo, wctx, mynode, orig, fcd, fco, fca, labels=None):
     """perform a 3-way merge in the working directory



To: spectral, #hg-reviewers
Cc: mercurial-devel