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
$ 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 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 or 'hg merge --abort' to abandon
[1]
$ hg id
618808747361+c0c68e4fe667+ tip
$ echo "[commands]" >> $HGRCPATH
$ echo "status.verbose=true" >> $HGRCPATH
$ hg status
M a
? a.orig
# The repository is in an unfinished *merge* state.
# Unresolved merge conflicts:
#
# a
#
# To mark files as resolved: hg resolve --mark FILE
# To continue: hg commit
# To abort: hg merge --abort
$ hg status -Tjson
[
{
"itemtype": "file",
"path": "a",
"status": "M",
"unresolved": true
},
{
"itemtype": "file",
"path": "a.orig",
"status": "?"
},
{
"itemtype": "morestatus",
"unfinished": "merge",
"unfinishedmsg": "To continue: hg commit\nTo abort: hg merge --abort"
}
]
$ hg status -0
M a\x00? a.orig\x00 (no-eol) (esc)
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< working copy: 618808747361 - test: branch2
6
8
=======
4
5
>>>>>>> merge rev: c0c68e4fe667 - test: branch1
Hop we are done.
$ hg status --config commands.status.verbose=0
M a
? a.orig
Verify custom conflict markers
$ hg up -q --clean .
$ cat <<EOF >> .hg/hgrc
> [command-templates]
> mergemarker = '{author} {rev}'
> EOF
$ hg merge 1
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 or 'hg merge --abort' to abandon
[1]
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< working copy: test 2
6
8
=======
4
5
>>>>>>> merge rev: test 1
Hop we are done.
Verify custom conflict markers with legacy config name
$ hg up -q --clean .
$ cat <<EOF >> .hg/hgrc
> [ui]
> mergemarkertemplate = '{author} {rev}'
> EOF
$ hg merge 1
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 or 'hg merge --abort' to abandon
[1]
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< working copy: test 2
6
8
=======
4
5
>>>>>>> merge rev: 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
> [command-templates]
> mergemarker={author} {rev}\nfoo\nbar\nbaz
> EOF
$ hg -q merge 1
warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
[1]
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< working copy: test 2
6
8
=======
4
5
>>>>>>> merge rev: 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', 'wb')
> fp.write(b'12345678901234567890123456789012345678901234567890' +
> b'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
> [command-templates]
> mergemarker={desc|firstline}
> EOF
$ hg -q --encoding utf-8 merge 1
warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
[1]
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< working copy: 1234567890123456789012345678901234567890123456789012345...
6
8
=======
4
5
>>>>>>> merge rev: 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 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 or 'hg merge --abort' to abandon
[1]
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< working copy
6
8
=======
4
5
>>>>>>> merge rev
Hop we are done.
internal:merge3
$ hg up -q --clean .
$ hg merge 1 --tool internal:merge3
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 or 'hg merge --abort' to abandon
[1]
$ cat a
Small Mathematical Series.
<<<<<<< working copy
1
2
3
6
8
||||||| base
One
Two
Three
Four
Five
=======
1
2
3
4
5
>>>>>>> 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
$ hg up -C
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
updated to "e0693e20f496: 123456789012345678901234567890123456789012345678901234567890????"
1 other heads for branch "default"
$ printf "\n\nEnd of file\n" >> a
$ hg ci -m "Add some stuff at the end"
$ hg up -r 1
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ printf "Start of file\n\n\n" > tmp
$ cat a >> tmp
$ mv tmp a
$ hg ci -m "Add some stuff at the beginning"
Now test :merge-other and :merge-local
$ hg merge
merging a
warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
1 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
[1]
$ hg resolve --tool :merge-other a
merging a
(no more unresolved files)
$ cat a
Start of file
Small Mathematical Series.
1
2
3
6
8
Hop we are done.
End of file
$ hg up -C
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
updated to "18b51d585961: Add some stuff at the beginning"
1 other heads for branch "default"
$ hg merge --tool :merge-local
merging a
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat a
Start of file
Small Mathematical Series.
1
2
3
4
5
Hop we are done.
End of file