view tests/test-state-extension.t @ 48507:58a3be48ddd2

simplemerge: stop merging file flags

As 384df4db6520 (merge: merge file flags together with file content,
2013-01-09) explains, we shouldn't do a 3-way merge of the
symlink. However, since 84614212ae39 (flags: actually merge flags in
simplemerge, 2020-05-16), we do that in
`simplemerge.simplemerge()`. What's more, the merging of the
executable flag there isn't actually necessary; it was made a no-op by
the very next commit, i.e. 4234c9af515d (flags: read flag from
dirstate/disk for workingcopyctx (issue5743), 2020-05-16).

I found the overall flag-merging code (not the bit in
`simplemerge.py`) very hard to follow, but I think I now finally
understand how it works. `mergestate.resolve()` calculates the merged
file flags and sets them on the local side of the merge (confusingly
by calling `_restore_backup()`). Then it calls
`filemerge.filemerge()`, which in turn calls
`simplemerge.simplemerge()` (if premerge is enabled). That means that
the flags on the local side `fcs.flags()` are already correct when the
flag-merging code in `simplemerge.simplemerge()` runs. Interestingly,
that code still works when the local side already has the merged
value, it just doesn't change the value. Here's a truth table to
explain why:

```
BLOMCAR
0000000
0011111
0101011
0111111
1000000
1010000
1100000
1111101
```

B: Base
L: Local
O: Other
M: Merged flags from `mergestate.resolve()`, i.e. what's called "local"
   when we get to `simplemerge.simplemerge()`
C: `commonflags` in `simplemerge.simplemerge()`, i.e. `M & O`
A: `addedflags` in `simplemerge.simplemerge()`, i.e. `(M ^ O) - B`
R: Re-merged flags `simplemerge.simplemerge()`, i.e. `C | A`

As you can see, the re-merged flags are always unchanged compared to
the initial merged flags (R equals M).

Therefore, this patch effectively backs out 84614212ae39. (I might
later refactor this code to have the flags explicitly passed in.)

`simplemerge.simplemerge()` is also called from
`contrib/simplemerge.py`, but that code never passes any flags.

Differential Revision: https://phab.mercurial-scm.org/D11879

Test extension of unfinished states support.
  $ mkdir chainify
  $ cd chainify
  $ cat >> chainify.py <<EOF
  > from mercurial import cmdutil, error, extensions, exthelper, node, scmutil, state
  > from hgext import rebase
  > 
  > eh = exthelper.exthelper()
  > 
  > extsetup = eh.finalextsetup
  > cmdtable = eh.cmdtable
  > 
  > # Rebase calls addunfinished in uisetup, so we have to call it in extsetup.
  > # Ideally there'd by an 'extensions.afteruisetup()' just like
  > # 'extensions.afterloaded()' to allow nesting multiple commands.
  > @eh.extsetup
  > def _extsetup(ui):
  >     state.addunfinished(
  >         b'chainify',
  >         b'chainify.state',
  >         continueflag=True,
  >         childopnames=[b'rebase'])
  > 
  > def _node(repo, arg):
  >     return node.hex(scmutil.revsingle(repo, arg).node())
  > 
  > @eh.command(
  >     b'chainify',
  >     [(b'r', b'revs', [], b'revs to chain', b'REV'),
  >      (b'', b'continue', False, b'continue op')],
  >     b'chainify [-r REV] +',
  >     inferrepo=True)
  > def chainify(ui, repo, **opts):
  >     """Rebases r1, r2, r3, etc. into a chain."""
  >     with repo.wlock(), repo.lock():
  >         cmdstate = state.cmdstate(repo, b'chainify.state')
  >         if opts['continue']:
  >             if not cmdstate.exists():
  >                 raise error.Abort(b'no chainify in progress')
  >         else:
  >             cmdutil.checkunfinished(repo)
  >             data = {
  >                 b'tip': _node(repo, opts['revs'][0]),
  >                 b'revs': b','.join(_node(repo, r) for r in opts['revs'][1:]),
  >             }
  >             cmdstate.save(1, data)
  > 
  >         data = cmdstate.read()
  >         while data[b'revs']:
  >             tip = data[b'tip']
  >             revs = data[b'revs'].split(b',')
  >             with state.delegating(repo, b'chainify', b'rebase'):
  >                 ui.status(b'rebasing %s onto %s\n' % (revs[0][:12], tip[:12]))
  >                 if state.ischildunfinished(repo, b'chainify', b'rebase'):
  >                     rc = state.continuechild(ui, repo, b'chainify', b'rebase')
  >                 else:
  >                     rc = rebase.rebase(ui, repo, rev=[revs[0]], dest=tip)
  >                 if rc and rc != 0:
  >                     raise error.Abort(b'rebase failed (rc: %d)' % rc)
  >             data[b'tip'] = _node(repo, b'tip')
  >             data[b'revs'] = b','.join(revs[1:])
  >             cmdstate.save(1, data)
  >         cmdstate.delete()
  >         ui.status(b'done chainifying\n')
  > EOF

  $ chainifypath=`pwd`/chainify.py
  $ echo '[extensions]' >> $HGRCPATH
  $ echo "chainify = $chainifypath" >> $HGRCPATH
  $ echo "rebase =" >> $HGRCPATH

  $ cd $TESTTMP
  $ hg init a
  $ cd a
  $ echo base > base.txt
  $ hg commit -Aqm 'base commit'
  $ echo foo > file1
  $ hg commit -Aqm 'add file'
  $ hg co -q ".^"
  $ echo bar > file2
  $ hg commit -Aqm 'add other file'
  $ hg co -q ".^"
  $ echo foo2 > file1
  $ hg commit -Aqm 'add conflicting file'
  $ hg co -q ".^"
  $ hg log --graph --template '{rev} {files}'
  o  3 file1
  |
  | o  2 file2
  |/
  | o  1 file1
  |/
  @  0 base.txt
  
  $ hg chainify -r 8430cfdf77c2 -r f8596309dff8 -r a858b338b3e9
  rebasing f8596309dff8 onto 8430cfdf77c2
  rebasing 2:f8596309dff8 "add other file"
  saved backup bundle to $TESTTMP/* (glob)
  rebasing a858b338b3e9 onto 83c722183a8e
  rebasing 2:a858b338b3e9 "add conflicting file"
  merging file1
  warning: conflicts while merging file1! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see 'hg resolve', then 'hg chainify --continue')
  [240]
  $ hg status --config commands.status.verbose=True
  M file1
  ? file1.orig
  # The repository is in an unfinished *chainify* state.
  
  # Unresolved merge conflicts:
  # 
  #     file1
  # 
  # To mark files as resolved:  hg resolve --mark FILE
  
  # To continue:    hg chainify --continue
  # To abort:       hg chainify --abort
  
  $ echo foo3 > file1
  $ hg resolve --mark file1
  (no more unresolved files)
  continue: hg chainify --continue
  $ hg chainify --continue
  rebasing a858b338b3e9 onto 83c722183a8e
  rebasing 2:a858b338b3e9 "add conflicting file"
  saved backup bundle to $TESTTMP/* (glob)
  done chainifying
  $ hg log --graph --template '{rev} {files}'
  o  3 file1
  |
  o  2 file2
  |
  o  1 file1
  |
  @  0 base.txt