annotate tests/test-conflict.t @ 28072:c3e9269d9602

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.

  $ 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