rebase: do not add second parent to rebased changeset (drop detach option) (BC)

Rebase now behaves as if --detach was always passed. Non-merges are
rebased as non-merges, regardless of their parent being an ancestor of
the destination. Merges will usually be rebased as merges unless both of
their parents are ancestors of the destination, or one of their parents
is pruned when rebased.

This only alters the behavior of rebase when using the --source/--rev
options. --detach option is deprecated.

All test changes were carefully validated.

hgext/rebase.py

@@ -48,8 +48,7 b" testedwith = 'internal'"
      _('read collapse commit message from file'), _('FILE')),
     ('', 'keep', False, _('keep original changesets')),
     ('', 'keepbranches', False, _('keep original branch names')),
-    ('D', 'detach', False, _('force detaching of source from its original '
-                            'branch')),
+    ('D', 'detach', False, _('(DEPRECATED)')),
     ('t', 'tool', '', _('specify merge tool')),
     ('c', 'continue', False, _('continue an interrupted rebase')),
     ('a', 'abort', False, _('abort an interrupted rebase'))] +
@@ -131,7 +130,6 b' def rebase(ui, repo, **opts):'
         extrafn = opts.get('extrafn') # internal, used by e.g. hgsubversion
         keepf = opts.get('keep', False)
         keepbranchesf = opts.get('keepbranches', False)
-        detachf = opts.get('detach', False)
         # keepopen is not meant for use on the command line, but by
         # other extensions
         keepopen = opts.get('keepopen', False)
@@ -146,8 +144,6 b' def rebase(ui, repo, **opts):'
             if collapsef:
                 raise util.Abort(
                     _('cannot use collapse with continue or abort'))
-            if detachf:
-                raise util.Abort(_('cannot use detach with continue or abort'))
             if srcf or basef or destf:
                 raise util.Abort(
                     _('abort and continue do not allow specifying revisions'))
@@ -168,12 +164,6 b' def rebase(ui, repo, **opts):'
             if revf and srcf:
                 raise util.Abort(_('cannot specify both a '
                                    'revision and a source'))
-            if detachf:
-                if not (srcf or revf):
-                    raise util.Abort(
-                        _('detach requires a revision to be specified'))
-                if basef:
-                    raise util.Abort(_('cannot specify a base with detach'))
 
             cmdutil.bailifchanged(repo)
 
@@ -215,7 +205,7 b' def rebase(ui, repo, **opts):'
                                  % repo[root],
                                  hint=_('see hg help phases for details'))
             else:
-                result = buildstate(repo, dest, rebaseset, detachf, collapsef)
+                result = buildstate(repo, dest, rebaseset, collapsef)
 
             if not result:
                 # Empty state built, nothing to rebase
@@ -592,13 +582,13 b' def abort(repo, originalwd, target, stat'
         repo.ui.warn(_('rebase aborted\n'))
         return 0
 
-def buildstate(repo, dest, rebaseset, detach, collapse):
+def buildstate(repo, dest, rebaseset, collapse):
     '''Define which revisions are going to be rebased and where
 
     repo: repo
     dest: context
     rebaseset: set of rev
-    detach: boolean'''
+    '''
 
     # This check isn't strictly necessary, since mq detects commits over an
     # applied patch. But it prevents messing up the working directory when
@@ -607,7 +597,6 b' def buildstate(repo, dest, rebaseset, de'
                             [s.node for s in repo.mq.applied]):
         raise util.Abort(_('cannot rebase onto an applied mq patch'))
 
-    detachset = set()
     roots = list(repo.set('roots(%ld)', rebaseset))
     if not roots:
         raise util.Abort(_('no matching revisions'))
@@ -623,14 +612,50 b' def buildstate(repo, dest, rebaseset, de'
         if not collapse and samebranch and root in dest.children():
             repo.ui.debug('source is a child of destination\n')
             return None
-        # rebase on ancestor, force detach
-        detach = True
-    if detach:
-        detachset = repo.revs('::%d - ::%d - %d', root, commonbase, root)
 
     repo.ui.debug('rebase onto %d starting from %d\n' % (dest, root))
     state = dict.fromkeys(rebaseset, nullrev)
-    state.update(dict.fromkeys(detachset, nullmerge))
+    # Rebase tries to turn <dest> into a parent of <root> while
+    # preserving the number of parents of rebased changesets:
+    #
+    # - A changeset with a single parent will always be rebased as a
+    #   changeset with a single parent.
+    #
+    # - A merge will be rebased as merge unless its parents are both
+    #   ancestors of <dest> or are themselves in the rebased set and
+    #   pruned while rebased.
+    #
+    # If one parent of <root> is an ancestor of <dest>, the rebased
+    # version of this parent will be <dest>. This is always true with
+    # --base option.
+    #
+    # Otherwise, we need to *replace* the original parents with
+    # <dest>. This "detaches" the rebased set from its former location
+    # and rebases it onto <dest>. Changes introduced by ancestors of
+    # <root> not common with <dest> (the detachset, marked as
+    # nullmerge) are "removed" from the rebased changesets.
+    #
+    # - If <root> has a single parent, set it to <dest>.
+    #
+    # - If <root> is a merge, we cannot decide which parent to
+    #   replace, the rebase operation is not clearly defined.
+    #
+    # The table below sums up this behavior:
+    #
+    # +--------------------+----------------------+-------------------------+
+    # |                    |     one parent       |  merge                  |
+    # +--------------------+----------------------+-------------------------+
+    # | parent in ::<dest> | new parent is <dest> | parents in ::<dest> are |
+    # |                    |                      | remapped to <dest>      |
+    # +--------------------+----------------------+-------------------------+
+    # | unrelated source   | new parent is <dest> | ambiguous, abort        |
+    # +--------------------+----------------------+-------------------------+
+    #
+    # The actual abort is handled by `defineparents`
+    if len(root.parents()) <= 1:
+        # (strict) ancestors of <root> not ancestors of <dest>
+        detachset = repo.revs('::%d - ::%d - %d', root, commonbase, root)
+        state.update(dict.fromkeys(detachset, nullmerge))
     return repo['.'].rev(), dest.rev(), state
 
 def pullrebase(orig, ui, repo, *args, **opts):

tests/test-bookmarks-rebase.t

@@ -39,11 +39,10 b' rebase'
   saved backup bundle to $TESTTMP/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg log
-  changeset:   3:9163974d1cb5
+  changeset:   3:42e5ed2cdcf4
   bookmark:    two
   tag:         tip
   parent:      1:925d80f479bb
-  parent:      2:db815d6d32e6
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     3

tests/test-rebase-bookmarks.t

@@ -54,7 +54,7 b' Move only rebased bookmarks'
   $ cd a1
   $ hg up -q Z
 
-  $ hg rebase --detach -s Y -d 3
+  $ hg rebase -s Y -d 3
   saved backup bundle to $TESTTMP/a1/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg tglog 

tests/test-rebase-cache.t

@@ -104,7 +104,7 b' Rebase part of branch2 (5-6) onto branch'
   2: 'B' branch1
   0: 'A' 
 
-  $ hg rebase --detach -s 5 -d 8
+  $ hg rebase -s 5 -d 8
   saved backup bundle to $TESTTMP/a1/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg branches
@@ -165,7 +165,7 b' Rebase head of branch3 (8) onto branch2 '
   |/
   o  0: 'A'
   
-  $ hg rebase --detach -s 8 -d 6
+  $ hg rebase -s 8 -d 6
   saved backup bundle to $TESTTMP/a2/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg branches
@@ -229,7 +229,7 b' Rebase entire branch3 (7-8) onto branch2'
   |/
   o  0: 'A'
   
-  $ hg rebase --detach -s 7 -d 6
+  $ hg rebase -s 7 -d 6
   saved backup bundle to $TESTTMP/a3/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg branches

tests/test-rebase-collapse.t

@@ -230,7 +230,7 b' Rebase and collapse - more than one exte'
 
 Rebase and collapse - E onto H:
 
-  $ hg rebase -s 4 --collapse
+  $ hg rebase -s 4 --collapse # root (4) is not a merge
   saved backup bundle to $TESTTMP/b1/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg tglog
@@ -250,7 +250,6 b' Rebase and collapse - E onto H:'
   
   $ hg manifest
   A
-  B
   C
   D
   E
@@ -340,7 +339,7 b' Rebase and collapse - E onto I:'
   $ hg clone -q -u . c c1
   $ cd c1
 
-  $ hg rebase -s 4 --collapse
+  $ hg rebase -s 4 --collapse # root (4) is not a merge
   merging E
   saved backup bundle to $TESTTMP/c1/.hg/strip-backup/*-backup.hg (glob)
 
@@ -362,7 +361,6 b' Rebase and collapse - E onto I:'
   
   $ hg manifest
   A
-  B
   C
   D
   E

tests/test-rebase-detach.t

@@ -48,7 +48,7 b' Rebasing D onto H detaching from C:'
   o  0: 'A'
   
   $ hg phase --force --secret 3
-  $ hg rebase --detach -s 3 -d 7
+  $ hg rebase -s 3 -d 7
   saved backup bundle to $TESTTMP/a1/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg log -G --template "{rev}:{phase} '{desc}' {branches}\n"
@@ -99,7 +99,7 b' Rebasing C onto H detaching from B:'
   |/
   o  0: 'A'
   
-  $ hg rebase --detach -s 2 -d 7
+  $ hg rebase -s 2 -d 7
   saved backup bundle to $TESTTMP/a2/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg tglog
@@ -151,7 +151,7 b' Rebasing B onto H using detach (same as '
   |/
   o  0: 'A'
   
-  $ hg rebase --detach -s 1 -d 7
+  $ hg rebase -s 1 -d 7
   saved backup bundle to $TESTTMP/a3/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg tglog
@@ -205,7 +205,7 b' Rebasing C onto H detaching from B and c'
   |/
   o  0: 'A'
   
-  $ hg rebase --detach --collapse -s 2 -d 7
+  $ hg rebase --collapse -s 2 -d 7
   saved backup bundle to $TESTTMP/a4/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg  log -G --template "{rev}:{phase} '{desc}' {branches}\n"
@@ -264,7 +264,7 b' Rebasing across null as ancestor'
   |/
   o  0: 'A'
   
-  $ hg rebase --detach -s 1 -d tip
+  $ hg rebase -s 1 -d tip
   saved backup bundle to $TESTTMP/a5/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg tglog
@@ -325,7 +325,7 b' Verify that target is not selected as ex'
   $ echo "J" >> F
   $ hg ci -m "J"
 
-  $ hg rebase -s 8 -d 7 --collapse --detach --config ui.merge=internal:other
+  $ hg rebase -s 8 -d 7 --collapse --config ui.merge=internal:other
   remote changed E which local deleted
   use (c)hanged version or leave (d)eleted? c
   saved backup bundle to $TESTTMP/a6/.hg/strip-backup/*-backup.hg (glob)
@@ -370,7 +370,7 b' Ensure --continue restores a correct sta'
   $ hg ci -A -m 'H2'
   adding H
   $ hg phase --force --secret 8
-  $ hg rebase -s 8 -d 7 --detach --config ui.merge=internal:fail
+  $ hg rebase -s 8 -d 7 --config ui.merge=internal:fail
   merging H
   warning: conflicts during merge.
   merging H incomplete! (edit conflicts, then use 'hg resolve --mark')

tests/test-rebase-parameters.t

@@ -199,19 +199,19 b' Specify only source (from 2 onto 8):'
   $ hg tglog
   @  8: 'D'
   |
-  o    7: 'C'
-  |\
-  | o  6: 'I'
-  | |
-  | o  5: 'H'
+  o  7: 'C'
+  |
+  o  6: 'I'
+  |
+  o  5: 'H'
+  |
+  | o  4: 'G'
+  |/|
+  o |  3: 'F'
   | |
-  | | o  4: 'G'
-  | |/|
-  | o |  3: 'F'
-  | | |
-  | | o  2: 'E'
-  | |/
-  o |  1: 'B'
+  | o  2: 'E'
+  |/
+  | o  1: 'B'
   |/
   o  0: 'A'
   
@@ -283,7 +283,7 b' Specify source and dest (from 2 onto 7):'
   $ hg clone -q -u . a a7
   $ cd a7
 
-  $ hg rebase --detach --source 2 --dest 7
+  $ hg rebase --source 2 --dest 7
   saved backup bundle to $TESTTMP/a7/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg tglog
@@ -349,19 +349,19 b' Specify only revs (from 2 onto 8)'
   $ hg tglog
   @  8: 'D'
   |
-  o    7: 'C'
-  |\
-  | o  6: 'I'
-  | |
-  | o  5: 'H'
+  o  7: 'C'
+  |
+  o  6: 'I'
+  |
+  o  5: 'H'
+  |
+  | o  4: 'G'
+  |/|
+  o |  3: 'F'
   | |
-  | | o  4: 'G'
-  | |/|
-  | o |  3: 'F'
-  | | |
-  | | o  2: 'E'
-  | |/
-  o |  1: 'B'
+  | o  2: 'E'
+  |/
+  | o  1: 'B'
   |/
   o  0: 'A'
   

tests/test-rebase-scenario-global.t

@@ -52,19 +52,19 b' D onto H - simple rebase:'
   saved backup bundle to $TESTTMP/a1/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg tglog
-  @    7: 'D'
-  |\
-  | o  6: 'H'
+  @  7: 'D'
+  |
+  o  6: 'H'
+  |
+  | o  5: 'G'
+  |/|
+  o |  4: 'F'
   | |
-  | | o  5: 'G'
-  | |/|
-  | o |  4: 'F'
-  | | |
-  | | o  3: 'E'
-  | |/
-  o |  2: 'C'
+  | o  3: 'E'
+  |/
+  | o  2: 'C'
   | |
-  o |  1: 'B'
+  | o  1: 'B'
   |/
   o  0: 'A'
   
@@ -80,19 +80,19 b' D onto F - intermediate point:'
   saved backup bundle to $TESTTMP/a2/.hg/strip-backup/*-backup.hg (glob)
 
   $ hg tglog
-  @    7: 'D'
-  |\
-  | | o  6: 'H'
-  | |/
-  | | o  5: 'G'
-  | |/|
-  | o |  4: 'F'
-  | | |
-  | | o  3: 'E'
-  | |/
-  o |  2: 'C'
+  @  7: 'D'
+  |
+  | o  6: 'H'
+  |/
+  | o  5: 'G'
+  |/|
+  o |  4: 'F'
   | |
-  o |  1: 'B'
+  | o  3: 'E'
+  |/
+  | o  2: 'C'
+  | |
+  | o  1: 'B'
   |/
   o  0: 'A'
   
@@ -303,9 +303,9 b' Source phase greater or equal to destina'
   $ hg log --template "{phase}\n" -r 9
   secret
 Source phase lower than destination phase: new changeset get the phase of destination:
-  $ hg rebase -s7 -d9
-  saved backup bundle to $TESTTMP/a7/.hg/strip-backup/c9659aac0000-backup.hg (glob)
-  $ hg log --template "{phase}\n" -r 9
+  $ hg rebase -s8 -d9
+  saved backup bundle to $TESTTMP/a7/.hg/strip-backup/6d4f22462821-backup.hg
+  $ hg log --template "{phase}\n" -r 'rev(9)'
   secret
 
   $ cd ..
@@ -404,20 +404,20 b' Base on have one descendant heads we ask'
   |
   o  10: 'G'
   |
-  o    9: 'D'
-  |\
-  | | o  8: 'I'
-  | | |
-  | | o  7: 'H'
+  o  9: 'D'
+  |
+  | o  8: 'I'
+  | |
+  | o  7: 'H'
+  | |
+  | o  6: 'G'
+  | |
+  | | o  5: 'F'
   | | |
-  | | o  6: 'G'
-  | | |
-  | | | o  5: 'F'
-  | | | |
-  | | | o  4: 'E'
-  | | |/
-  | | o  3: 'D'
+  | | o  4: 'E'
   | |/
+  | o  3: 'D'
+  | |
   | o  2: 'C'
   | |
   o |  1: 'B'
@@ -441,20 +441,20 b' rebase subset'
   |
   o  10: 'G'
   |
-  o    9: 'D'
-  |\
-  | | o  8: 'I'
-  | | |
-  | | o  7: 'H'
+  o  9: 'D'
+  |
+  | o  8: 'I'
+  | |
+  | o  7: 'H'
+  | |
+  | o  6: 'G'
+  | |
+  | | o  5: 'F'
   | | |
-  | | o  6: 'G'
-  | | |
-  | | | o  5: 'F'
-  | | | |
-  | | | o  4: 'E'
-  | | |/
-  | | o  3: 'D'
+  | | o  4: 'E'
   | |/
+  | o  3: 'D'
+  | |
   | o  2: 'C'
   | |
   o |  1: 'B'
@@ -482,20 +482,20 b' rebase subset with multiple head'
   | |
   | o  10: 'E'
   |/
-  o    9: 'D'
-  |\
-  | | o  8: 'I'
-  | | |
-  | | o  7: 'H'
+  o  9: 'D'
+  |
+  | o  8: 'I'
+  | |
+  | o  7: 'H'
+  | |
+  | o  6: 'G'
+  | |
+  | | o  5: 'F'
   | | |
-  | | o  6: 'G'
-  | | |
-  | | | o  5: 'F'
-  | | | |
-  | | | o  4: 'E'
-  | | |/
-  | | o  3: 'D'
+  | | o  4: 'E'
   | |/
+  | o  3: 'D'
+  | |
   | o  2: 'C'
   | |
   o |  1: 'B'