# HG changeset patch # User Martin von Zweigbergk # Date 1607474713 28800 # Node ID bdc2bf68f19e456574cefe36bc5c9b165bb2fbfc # Parent aa4dbc14f7354557933072c99967d43f6d9c3c22 mergetools: add new conflict marker format with diffs in I use 3-way conflict markers. Often when I resolve them, I manually compare one the base with one side and apply the differences to the other side. That can be hard when the conflict marker is large. This patch introduces a new type of conflict marker, which I'm hoping will make it easier to resolve conflicts. The new format uses `<<<<<<<` and `>>>>>>>` to open and close the markers, just like our existing 2-way and 3-way conflict markers. Instead of having 2 or 3 snapshots (left+right or left+base+right), it has a sequence of diffs. A diff looks like this: ``` ------- base +++++++ left a -b +c d ``` A diff that adds one side ("diff from nothing") has a `=======` header instead and does not have have `+` prefixed on its lines. A regular 3-way merge can be viewed as adding one side plus a diff between the base and the other side. It thus has two ways of being represented, depending on which side is being diffed: ``` <<<<<<< ======= left contents on left ------- base +++++++ right contents on -left +right >>>>>>> ``` or ``` <<<<<<< ------- base +++++++ left contents on -right +left ======= right contents on right >>>>>>> ``` I've made it so the new merge tool tries to pick a version that has the most common lines (no difference in the example above). I've called the new tool "mergediff" to stick to the convention of starting with "merge" if the tool tries a regular 3-way merge. The idea came from my pet VCS (placeholder name `jj`), which has support for octopus merges and other ways of ending up with merges of more than 3 versions. I wanted to be able to represent such conflicts in the working copy and therefore thought of this format (although I have not yet implemented it in my VCS). I then attended a meeting with Larry McVoy, who said BitKeeper has an option (`bk smerge -g`) for showing a similar format, which reminded me to actually attempt this in Mercurial. Differential Revision: https://phab.mercurial-scm.org/D9551 diff -r aa4dbc14f735 -r bdc2bf68f19e mercurial/filemerge.py --- a/mercurial/filemerge.py Thu Dec 10 14:39:22 2020 -0800 +++ b/mercurial/filemerge.py Tue Dec 08 16:45:13 2020 -0800 @@ -532,6 +532,33 @@ return _imerge(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels) +@internaltool( + b'mergediff', + fullmerge, + _( + b"warning: conflicts while merging %s! " + b"(edit, then use 'hg resolve --mark')\n" + ), + precheck=_mergecheck, +) +def _imerge_diff( + 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. The marker will have two sections, one with the + content from one side of the merge, and one with a diff from the base + content to the content on the other side. (experimental)""" + if not labels: + labels = _defaultconflictlabels + if len(labels) < 3: + labels.append(b'base') + return _merge( + repo, mynode, orig, fcd, fco, fca, toolconf, files, labels, b'mergediff' + ) + + def _imergeauto( repo, mynode, diff -r aa4dbc14f735 -r bdc2bf68f19e mercurial/simplemerge.py --- a/mercurial/simplemerge.py Thu Dec 10 14:39:22 2020 -0800 +++ b/mercurial/simplemerge.py Tue Dec 08 16:45:13 2020 -0800 @@ -455,6 +455,68 @@ return ctx.node() != nodemod.nullid +def _mergediff(m3, name_a, name_b, name_base): + lines = [] + conflicts = False + for group in m3.merge_groups(): + if group[0] == b'conflict': + base_lines, a_lines, b_lines = group[1:] + base_text = b''.join(base_lines) + b_blocks = list( + mdiff.allblocks( + base_text, + b''.join(b_lines), + lines1=base_lines, + lines2=b_lines, + ) + ) + a_blocks = list( + mdiff.allblocks( + base_text, + b''.join(a_lines), + lines1=base_lines, + lines2=b_lines, + ) + ) + + def matching_lines(blocks): + return sum( + block[1] - block[0] + for block, kind in blocks + if kind == b'=' + ) + + def diff_lines(blocks, lines1, lines2): + for block, kind in blocks: + if kind == b'=': + for line in lines1[block[0] : block[1]]: + yield b' ' + line + else: + for line in lines1[block[0] : block[1]]: + yield b'-' + line + for line in lines2[block[2] : block[3]]: + yield b'+' + line + + lines.append(b"<<<<<<<\n") + if matching_lines(a_blocks) < matching_lines(b_blocks): + lines.append(b"======= %s\n" % name_a) + lines.extend(a_lines) + lines.append(b"------- %s\n" % name_base) + lines.append(b"+++++++ %s\n" % name_b) + lines.extend(diff_lines(b_blocks, base_lines, b_lines)) + else: + lines.append(b"------- %s\n" % name_base) + lines.append(b"+++++++ %s\n" % name_a) + lines.extend(diff_lines(a_blocks, base_lines, a_lines)) + lines.append(b"======= %s\n" % name_b) + lines.extend(b_lines) + lines.append(b">>>>>>>\n") + conflicts = True + else: + lines.extend(group[1]) + return lines, conflicts + + def simplemerge(ui, localctx, basectx, otherctx, **opts): """Performs the simplemerge algorithm. @@ -499,9 +561,15 @@ extrakwargs[b'name_base'] = name_base extrakwargs[b'minimize'] = False - lines = m3.merge_lines( - name_a=name_a, name_b=name_b, **pycompat.strkwargs(extrakwargs) - ) + if mode == b'mergediff': + lines, conflicts = _mergediff(m3, name_a, name_b, name_base) + else: + lines = list( + m3.merge_lines( + name_a=name_a, name_b=name_b, **pycompat.strkwargs(extrakwargs) + ) + ) + conflicts = m3.conflicts # merge flags if necessary flags = localctx.flags() @@ -519,5 +587,5 @@ else: localctx.write(mergedtext, flags) - if m3.conflicts and not mode == b'union': + if conflicts and not mode == b'union': return 1 diff -r aa4dbc14f735 -r bdc2bf68f19e relnotes/next --- a/relnotes/next Thu Dec 10 14:39:22 2020 -0800 +++ b/relnotes/next Tue Dec 08 16:45:13 2020 -0800 @@ -27,6 +27,13 @@ * The memory footprint per changeset during pull/unbundle operations has been further reduced. + * There is a new internal merge tool called `internal:mergediff` (can + be set as the value for the `merge` config in the `[ui]` + section). It resolves merges the same was as `internal:merge` and + `internal:merge3`, but it shows conflicts differently. Instead of + showing 2 or 3 snapshots of the conflicting pieces of code, it + shows one snapshot and a diff. This may be useful when at least one + side of the conflict is similar to the base. == New Experimental Features == diff -r aa4dbc14f735 -r bdc2bf68f19e tests/test-conflict.t --- a/tests/test-conflict.t Thu Dec 10 14:39:22 2020 -0800 +++ b/tests/test-conflict.t Tue Dec 08 16:45:13 2020 -0800 @@ -282,6 +282,80 @@ >>>>>>> merge rev Hop we are done. +internal:mergediff + + $ hg co -C 1 + 1 files updated, 0 files merged, 0 files removed, 0 files unresolved + $ cat << EOF > a + > Small Mathematical Series. + > 1 + > 2 + > 3 + > 4 + > 4.5 + > 5 + > Hop we are done. + > EOF + $ hg co -m 2 -t internal:mergediff + merging a + warning: conflicts while merging a! (edit, 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 + [1] + $ cat a + Small Mathematical Series. + 1 + 2 + 3 + <<<<<<< + ------- base + +++++++ working copy + 4 + +4.5 + 5 + ======= destination + 6 + 8 + >>>>>>> + Hop we are done. +Test the same thing as above but modify a bit more so we instead get the working +copy in full and the diff from base to destination. + $ hg co -C 1 + 1 files updated, 0 files merged, 0 files removed, 0 files unresolved + $ cat << EOF > a + > Small Mathematical Series. + > 1 + > 2 + > 3.5 + > 4.5 + > 5.5 + > Hop we are done. + > EOF + $ hg co -m 2 -t internal:mergediff + merging a + warning: conflicts while merging a! (edit, 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 + [1] + $ cat a + Small Mathematical Series. + 1 + 2 + <<<<<<< + ======= working copy + 3.5 + 4.5 + 5.5 + ------- base + +++++++ destination + 3 + -4 + -5 + +6 + +8 + >>>>>>> + Hop we are done. + Add some unconflicting changes on each head, to make sure we really are merging, unlike :local and :other diff -r aa4dbc14f735 -r bdc2bf68f19e tests/test-help.t --- a/tests/test-help.t Thu Dec 10 14:39:22 2020 -0800 +++ b/tests/test-help.t Tue Dec 08 16:45:13 2020 -0800 @@ -2057,6 +2057,13 @@ partially merged file. Marker will have three sections, one from each side of the merge and one for the base content. + ":mergediff" + 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. The marker will have two sections, one with the + content from one side of the merge, and one with a diff from the base + content to the content on the other side. (experimental) + ":other" Uses the other 'p2()' version of files as the merged version.