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merge: minimize conflicts when common base is not shown (issue4447)...
merge: minimize conflicts when common base is not shown (issue4447) Previously, two changes that were nearly, but not quite, identical would result in large merge conflict regions that looked very similar, and were thus very confusing to users, and lead people used to other source control systems to claim that "mercurial's merge algorithms suck". In the relatively common case of a new file being introduced in two branches with very slight modifications, the old behavior would show the entire file as a conflict, and it would be very difficult for a user to determine what was going on. In the past, mercurial attempted to solve this with a "very smart" algorithm that would find all common lines, but this has significant problems as described in 2ea6d906cf9b. Instead, we use a "very dumb" algorithm introduced in the previous patch that simply matches lines at the periphery of conflict regions. This minimizes most conflict regions well, though there may still be some degenerate edge cases, like small modification to the beginning and end of a large file.

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r28072:c3e9269d default
r28072:c3e9269d default
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test-conflict.t
276 lines | 5.3 KiB | text/troff | Tads3Lexer
$ 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 update -C .' to abandon
[1]
$ hg id
618808747361+c0c68e4fe667+ tip
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< local: 618808747361 - test: branch2
6
8
=======
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 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 update -C .' to abandon
[1]
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< local: test 2
6
8
=======
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 while merging a! (edit, then use 'hg resolve --mark')
[1]
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< local: test 2
6
8
=======
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 while merging a! (edit, then use 'hg resolve --mark')
[1]
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< local: 123456789012345678901234567890123456789012345678901234567890\xe3\x81\x82... (esc)
6
8
=======
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 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 update -C .' to abandon
[1]
$ cat a
Small Mathematical Series.
1
2
3
<<<<<<< local
6
8
=======
4
5
>>>>>>> other
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 update -C .' to abandon
[1]
$ cat a
Small Mathematical Series.
<<<<<<< local
1
2
3
6
8
||||||| base
One
Two
Three
Four
Five
=======
1
2
3
4
5
>>>>>>> other
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
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 update -C .' 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
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