view tests/test-rebase-conflicts.t @ 17103:5146de7bce96

convert: keep branch switching merges with ancestors (issue3340)

When running convert with a filemap, merge parents which are ancestors
of other parents are ignored. This is hardly a problem when parents
belong to the same branch, but the result could be confusing when named
branches are involved. With:

  -o-a1-a2-a3...     <- A
    \           \
     b1-b2-b3...-m-  <- B

If all b* revisions are discarded, it is useful to preserve 'm' even if
it is empty after filtering to record the branch switch.

This patch makes filemap preserve "ancestor parents" if there is no
"non-ancestor parent" on the same branch than the merge revision.

Remarks:
- I am not completely convinced by the reasons given above and those
  detailed by Matt in this thread:

http://selenic.com/pipermail/mercurial-devel/2012-May/040627.html

  The properties we try to preserve are not clearly defined. That said,
  I know this patch already helped someone on IRC and the tests output
  look reasonable.

- This is a new version of the original "convert: filemap must preserve
  fast-forward merges" patch. It has exactly the same output for 2
  parents merges, the additional complexity is here to handle more than
  two parents.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > graphlog=
  > rebase=
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog = log -G --template "{rev}:{phase} '{desc}' {branches}\n"
  > EOF

  $ hg init a
  $ cd a
  $ echo c1 >common
  $ hg add common
  $ hg ci -m C1

  $ echo c2 >>common
  $ hg ci -m C2

  $ echo c3 >>common
  $ hg ci -m C3

  $ hg up -q -C 1

  $ echo l1 >>extra
  $ hg add extra
  $ hg ci -m L1
  created new head

  $ sed -e 's/c2/l2/' common > common.new
  $ mv common.new common
  $ hg ci -m L2

  $ echo l3 >> extra2
  $ hg add extra2
  $ hg ci -m L3

  $ hg phase --force --secret 4

  $ hg tglog
  @  5:secret 'L3'
  |
  o  4:secret 'L2'
  |
  o  3:draft 'L1'
  |
  | o  2:draft 'C3'
  |/
  o  1:draft 'C2'
  |
  o  0:draft 'C1'
  
Try to call --continue:

  $ hg rebase --continue
  abort: no rebase in progress
  [255]

Conflicting rebase:

  $ hg rebase -s 3 -d 2
  merging common
  warning: conflicts during merge.
  merging common incomplete! (edit conflicts, then use 'hg resolve --mark')
  abort: unresolved conflicts (see hg resolve, then hg rebase --continue)
  [255]

Try to continue without solving the conflict:

  $ hg rebase --continue 
  abort: unresolved merge conflicts (see hg help resolve)
  [255]

Conclude rebase:

  $ echo 'resolved merge' >common
  $ hg resolve -m common
  $ hg rebase --continue
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  5:secret 'L3'
  |
  o  4:secret 'L2'
  |
  o  3:draft 'L1'
  |
  o  2:draft 'C3'
  |
  o  1:draft 'C2'
  |
  o  0:draft 'C1'
  
Check correctness:

  $ hg cat -r 0 common
  c1

  $ hg cat -r 1 common
  c1
  c2

  $ hg cat -r 2 common
  c1
  c2
  c3

  $ hg cat -r 3 common
  c1
  c2
  c3

  $ hg cat -r 4 common
  resolved merge

  $ hg cat -r 5 common
  resolved merge

  $ cd ..