rebase: stop relying on having two parents to resume rebase

I'm about to make it so we don't have two parents when a rebase is
interrupted (unless we're just rebasing on a merge commit). The code
for detecting if we're resuming a rebase relied on having two parents,
so this patch rewrites that to instead set a boolean when we resume.

Note that `self.resume` in the new condition implies `not
self.inmemory` (rebase cannot be resumed in memory), so that's why
that part can be omitted.

Differential Revision: https://phab.mercurial-scm.org/D7826

hgext/rebase.py

@@ -1,2248 +1,2251 b''
 # rebase.py - rebasing feature for mercurial
 #
 # Copyright 2008 Stefano Tortarolo <stefano.tortarolo at gmail dot com>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 '''command to move sets of revisions to a different ancestor
 
 This extension lets you rebase changesets in an existing Mercurial
 repository.
 
 For more information:
 https://mercurial-scm.org/wiki/RebaseExtension
 '''
 
 from __future__ import absolute_import
 
 import errno
 import os
 
 from mercurial.i18n import _
 from mercurial.node import (
     nullrev,
     short,
 )
 from mercurial.pycompat import open
 from mercurial import (
     bookmarks,
     cmdutil,
     commands,
     copies,
     destutil,
     dirstateguard,
     error,
     extensions,
     hg,
     merge as mergemod,
     mergeutil,
     node as nodemod,
     obsolete,
     obsutil,
     patch,
     phases,
     pycompat,
     registrar,
     repair,
     revset,
     revsetlang,
     rewriteutil,
     scmutil,
     smartset,
     state as statemod,
     util,
 )
 
 # The following constants are used throughout the rebase module. The ordering of
 # their values must be maintained.
 
 # Indicates that a revision needs to be rebased
 revtodo = -1
 revtodostr = b'-1'
 
 # legacy revstates no longer needed in current code
 # -2: nullmerge, -3: revignored, -4: revprecursor, -5: revpruned
 legacystates = {b'-2', b'-3', b'-4', b'-5'}
 
 cmdtable = {}
 command = registrar.command(cmdtable)
 # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
 # extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
 # be specifying the version(s) of Mercurial they are tested with, or
 # leave the attribute unspecified.
 testedwith = b'ships-with-hg-core'
 
 
 def _nothingtorebase():
     return 1
 
 
 def _savegraft(ctx, extra):
     s = ctx.extra().get(b'source', None)
     if s is not None:
         extra[b'source'] = s
     s = ctx.extra().get(b'intermediate-source', None)
     if s is not None:
         extra[b'intermediate-source'] = s
 
 
 def _savebranch(ctx, extra):
     extra[b'branch'] = ctx.branch()
 
 
 def _destrebase(repo, sourceset, destspace=None):
     """small wrapper around destmerge to pass the right extra args
 
     Please wrap destutil.destmerge instead."""
     return destutil.destmerge(
         repo,
         action=b'rebase',
         sourceset=sourceset,
         onheadcheck=False,
         destspace=destspace,
     )
 
 
 revsetpredicate = registrar.revsetpredicate()
 
 
 @revsetpredicate(b'_destrebase')
 def _revsetdestrebase(repo, subset, x):
     # ``_rebasedefaultdest()``
 
     # default destination for rebase.
     # # XXX: Currently private because I expect the signature to change.
     # # XXX: - bailing out in case of ambiguity vs returning all data.
     # i18n: "_rebasedefaultdest" is a keyword
     sourceset = None
     if x is not None:
         sourceset = revset.getset(repo, smartset.fullreposet(repo), x)
     return subset & smartset.baseset([_destrebase(repo, sourceset)])
 
 
 @revsetpredicate(b'_destautoorphanrebase')
 def _revsetdestautoorphanrebase(repo, subset, x):
     # ``_destautoorphanrebase()``
 
     # automatic rebase destination for a single orphan revision.
     unfi = repo.unfiltered()
     obsoleted = unfi.revs(b'obsolete()')
 
     src = revset.getset(repo, subset, x).first()
 
     # Empty src or already obsoleted - Do not return a destination
     if not src or src in obsoleted:
         return smartset.baseset()
     dests = destutil.orphanpossibledestination(repo, src)
     if len(dests) > 1:
         raise error.Abort(
             _(b"ambiguous automatic rebase: %r could end up on any of %r")
             % (src, dests)
         )
     # We have zero or one destination, so we can just return here.
     return smartset.baseset(dests)
 
 
 def _ctxdesc(ctx):
     """short description for a context"""
     desc = b'%d:%s "%s"' % (
         ctx.rev(),
         ctx,
         ctx.description().split(b'\n', 1)[0],
     )
     repo = ctx.repo()
     names = []
     for nsname, ns in pycompat.iteritems(repo.names):
         if nsname == b'branches':
             continue
         names.extend(ns.names(repo, ctx.node()))
     if names:
         desc += b' (%s)' % b' '.join(names)
     return desc
 
 
 class rebaseruntime(object):
     """This class is a container for rebase runtime state"""
 
     def __init__(self, repo, ui, inmemory=False, opts=None):
         if opts is None:
             opts = {}
 
         # prepared: whether we have rebasestate prepared or not. Currently it
         # decides whether "self.repo" is unfiltered or not.
         # The rebasestate has explicit hash to hash instructions not depending
         # on visibility. If rebasestate exists (in-memory or on-disk), use
         # unfiltered repo to avoid visibility issues.
         # Before knowing rebasestate (i.e. when starting a new rebase (not
         # --continue or --abort)), the original repo should be used so
         # visibility-dependent revsets are correct.
         self.prepared = False
+        self.resume = False
         self._repo = repo
 
         self.ui = ui
         self.opts = opts
         self.originalwd = None
         self.external = nullrev
         # Mapping between the old revision id and either what is the new rebased
         # revision or what needs to be done with the old revision. The state
         # dict will be what contains most of the rebase progress state.
         self.state = {}
         self.activebookmark = None
         self.destmap = {}
         self.skipped = set()
 
         self.collapsef = opts.get(b'collapse', False)
         self.collapsemsg = cmdutil.logmessage(ui, opts)
         self.date = opts.get(b'date', None)
 
         e = opts.get(b'extrafn')  # internal, used by e.g. hgsubversion
         self.extrafns = [_savegraft]
         if e:
             self.extrafns = [e]
 
         self.backupf = ui.configbool(b'rewrite', b'backup-bundle')
         self.keepf = opts.get(b'keep', False)
         self.keepbranchesf = opts.get(b'keepbranches', False)
         self.obsoletenotrebased = {}
         self.obsoletewithoutsuccessorindestination = set()
         self.inmemory = inmemory
         self.stateobj = statemod.cmdstate(repo, b'rebasestate')
 
     @property
     def repo(self):
         if self.prepared:
             return self._repo.unfiltered()
         else:
             return self._repo
 
     def storestatus(self, tr=None):
         """Store the current status to allow recovery"""
         if tr:
             tr.addfilegenerator(
                 b'rebasestate',
                 (b'rebasestate',),
                 self._writestatus,
                 location=b'plain',
             )
         else:
             with self.repo.vfs(b"rebasestate", b"w") as f:
                 self._writestatus(f)
 
     def _writestatus(self, f):
         repo = self.repo
         assert repo.filtername is None
         f.write(repo[self.originalwd].hex() + b'\n')
         # was "dest". we now write dest per src root below.
         f.write(b'\n')
         f.write(repo[self.external].hex() + b'\n')
         f.write(b'%d\n' % int(self.collapsef))
         f.write(b'%d\n' % int(self.keepf))
         f.write(b'%d\n' % int(self.keepbranchesf))
         f.write(b'%s\n' % (self.activebookmark or b''))
         destmap = self.destmap
         for d, v in pycompat.iteritems(self.state):
             oldrev = repo[d].hex()
             if v >= 0:
                 newrev = repo[v].hex()
             else:
                 newrev = b"%d" % v
             destnode = repo[destmap[d]].hex()
             f.write(b"%s:%s:%s\n" % (oldrev, newrev, destnode))
         repo.ui.debug(b'rebase status stored\n')
 
     def restorestatus(self):
         """Restore a previously stored status"""
         if not self.stateobj.exists():
             cmdutil.wrongtooltocontinue(self.repo, _(b'rebase'))
 
         data = self._read()
         self.repo.ui.debug(b'rebase status resumed\n')
 
         self.originalwd = data[b'originalwd']
         self.destmap = data[b'destmap']
         self.state = data[b'state']
         self.skipped = data[b'skipped']
         self.collapsef = data[b'collapse']
         self.keepf = data[b'keep']
         self.keepbranchesf = data[b'keepbranches']
         self.external = data[b'external']
         self.activebookmark = data[b'activebookmark']
 
     def _read(self):
         self.prepared = True
         repo = self.repo
         assert repo.filtername is None
         data = {
             b'keepbranches': None,
             b'collapse': None,
             b'activebookmark': None,
             b'external': nullrev,
             b'keep': None,
             b'originalwd': None,
         }
         legacydest = None
         state = {}
         destmap = {}
 
         if True:
             f = repo.vfs(b"rebasestate")
             for i, l in enumerate(f.read().splitlines()):
                 if i == 0:
                     data[b'originalwd'] = repo[l].rev()
                 elif i == 1:
                     # this line should be empty in newer version. but legacy
                     # clients may still use it
                     if l:
                         legacydest = repo[l].rev()
                 elif i == 2:
                     data[b'external'] = repo[l].rev()
                 elif i == 3:
                     data[b'collapse'] = bool(int(l))
                 elif i == 4:
                     data[b'keep'] = bool(int(l))
                 elif i == 5:
                     data[b'keepbranches'] = bool(int(l))
                 elif i == 6 and not (len(l) == 81 and b':' in l):
                     # line 6 is a recent addition, so for backwards
                     # compatibility check that the line doesn't look like the
                     # oldrev:newrev lines
                     data[b'activebookmark'] = l
                 else:
                     args = l.split(b':')
                     oldrev = repo[args[0]].rev()
                     newrev = args[1]
                     if newrev in legacystates:
                         continue
                     if len(args) > 2:
                         destrev = repo[args[2]].rev()
                     else:
                         destrev = legacydest
                     destmap[oldrev] = destrev
                     if newrev == revtodostr:
                         state[oldrev] = revtodo
                         # Legacy compat special case
                     else:
                         state[oldrev] = repo[newrev].rev()
 
         if data[b'keepbranches'] is None:
             raise error.Abort(_(b'.hg/rebasestate is incomplete'))
 
         data[b'destmap'] = destmap
         data[b'state'] = state
         skipped = set()
         # recompute the set of skipped revs
         if not data[b'collapse']:
             seen = set(destmap.values())
             for old, new in sorted(state.items()):
                 if new != revtodo and new in seen:
                     skipped.add(old)
                 seen.add(new)
         data[b'skipped'] = skipped
         repo.ui.debug(
             b'computed skipped revs: %s\n'
             % (b' '.join(b'%d' % r for r in sorted(skipped)) or b'')
         )
 
         return data
 
     def _handleskippingobsolete(self, obsoleterevs, destmap):
         """Compute structures necessary for skipping obsolete revisions
 
         obsoleterevs:   iterable of all obsolete revisions in rebaseset
         destmap:        {srcrev: destrev} destination revisions
         """
         self.obsoletenotrebased = {}
         if not self.ui.configbool(b'experimental', b'rebaseskipobsolete'):
             return
         obsoleteset = set(obsoleterevs)
         (
             self.obsoletenotrebased,
             self.obsoletewithoutsuccessorindestination,
             obsoleteextinctsuccessors,
         ) = _computeobsoletenotrebased(self.repo, obsoleteset, destmap)
         skippedset = set(self.obsoletenotrebased)
         skippedset.update(self.obsoletewithoutsuccessorindestination)
         skippedset.update(obsoleteextinctsuccessors)
         _checkobsrebase(self.repo, self.ui, obsoleteset, skippedset)
 
     def _prepareabortorcontinue(self, isabort, backup=True, suppwarns=False):
+        self.resume = True
         try:
             self.restorestatus()
             self.collapsemsg = restorecollapsemsg(self.repo, isabort)
         except error.RepoLookupError:
             if isabort:
                 clearstatus(self.repo)
                 clearcollapsemsg(self.repo)
                 self.repo.ui.warn(
                     _(
                         b'rebase aborted (no revision is removed,'
                         b' only broken state is cleared)\n'
                     )
                 )
                 return 0
             else:
                 msg = _(b'cannot continue inconsistent rebase')
                 hint = _(b'use "hg rebase --abort" to clear broken state')
                 raise error.Abort(msg, hint=hint)
 
         if isabort:
             backup = backup and self.backupf
             return self._abort(backup=backup, suppwarns=suppwarns)
 
     def _preparenewrebase(self, destmap):
         if not destmap:
             return _nothingtorebase()
 
         rebaseset = destmap.keys()
         if not self.keepf:
             try:
                 rewriteutil.precheck(self.repo, rebaseset, action=b'rebase')
             except error.Abort as e:
                 if e.hint is None:
                     e.hint = _(b'use --keep to keep original changesets')
                 raise e
 
         result = buildstate(self.repo, destmap, self.collapsef)
 
         if not result:
             # Empty state built, nothing to rebase
             self.ui.status(_(b'nothing to rebase\n'))
             return _nothingtorebase()
 
         (self.originalwd, self.destmap, self.state) = result
         if self.collapsef:
             dests = set(self.destmap.values())
             if len(dests) != 1:
                 raise error.Abort(
                     _(b'--collapse does not work with multiple destinations')
                 )
             destrev = next(iter(dests))
             destancestors = self.repo.changelog.ancestors(
                 [destrev], inclusive=True
             )
             self.external = externalparent(self.repo, self.state, destancestors)
 
         for destrev in sorted(set(destmap.values())):
             dest = self.repo[destrev]
             if dest.closesbranch() and not self.keepbranchesf:
                 self.ui.status(_(b'reopening closed branch head %s\n') % dest)
 
         self.prepared = True
 
     def _assignworkingcopy(self):
         if self.inmemory:
             from mercurial.context import overlayworkingctx
 
             self.wctx = overlayworkingctx(self.repo)
             self.repo.ui.debug(b"rebasing in-memory\n")
         else:
             self.wctx = self.repo[None]
             self.repo.ui.debug(b"rebasing on disk\n")
         self.repo.ui.log(
             b"rebase",
             b"using in-memory rebase: %r\n",
             self.inmemory,
             rebase_imm_used=self.inmemory,
         )
 
     def _performrebase(self, tr):
         self._assignworkingcopy()
         repo, ui = self.repo, self.ui
         if self.keepbranchesf:
             # insert _savebranch at the start of extrafns so if
             # there's a user-provided extrafn it can clobber branch if
             # desired
             self.extrafns.insert(0, _savebranch)
             if self.collapsef:
                 branches = set()
                 for rev in self.state:
                     branches.add(repo[rev].branch())
                     if len(branches) > 1:
                         raise error.Abort(
                             _(b'cannot collapse multiple named branches')
                         )
 
         # Calculate self.obsoletenotrebased
         obsrevs = _filterobsoleterevs(self.repo, self.state)
         self._handleskippingobsolete(obsrevs, self.destmap)
 
         # Keep track of the active bookmarks in order to reset them later
         self.activebookmark = self.activebookmark or repo._activebookmark
         if self.activebookmark:
             bookmarks.deactivate(repo)
 
         # Store the state before we begin so users can run 'hg rebase --abort'
         # if we fail before the transaction closes.
         self.storestatus()
         if tr:
             # When using single transaction, store state when transaction
             # commits.
             self.storestatus(tr)
 
         cands = [k for k, v in pycompat.iteritems(self.state) if v == revtodo]
         p = repo.ui.makeprogress(
             _(b"rebasing"), unit=_(b'changesets'), total=len(cands)
         )
 
         def progress(ctx):
             p.increment(item=(b"%d:%s" % (ctx.rev(), ctx)))
 
         allowdivergence = self.ui.configbool(
             b'experimental', b'evolution.allowdivergence'
         )
         for subset in sortsource(self.destmap):
             sortedrevs = self.repo.revs(b'sort(%ld, -topo)', subset)
             if not allowdivergence:
                 sortedrevs -= self.repo.revs(
                     b'descendants(%ld) and not %ld',
                     self.obsoletewithoutsuccessorindestination,
                     self.obsoletewithoutsuccessorindestination,
                 )
             for rev in sortedrevs:
                 self._rebasenode(tr, rev, allowdivergence, progress)
         p.complete()
         ui.note(_(b'rebase merging completed\n'))
 
     def _concludenode(self, rev, p1, p2, editor, commitmsg=None):
         '''Commit the wd changes with parents p1 and p2.
 
         Reuse commit info from rev but also store useful information in extra.
         Return node of committed revision.'''
         repo = self.repo
         ctx = repo[rev]
         if commitmsg is None:
             commitmsg = ctx.description()
         date = self.date
         if date is None:
             date = ctx.date()
         extra = {b'rebase_source': ctx.hex()}
         for c in self.extrafns:
             c(ctx, extra)
         keepbranch = self.keepbranchesf and repo[p1].branch() != ctx.branch()
         destphase = max(ctx.phase(), phases.draft)
         overrides = {(b'phases', b'new-commit'): destphase}
         if keepbranch:
             overrides[(b'ui', b'allowemptycommit')] = True
         with repo.ui.configoverride(overrides, b'rebase'):
             if self.inmemory:
                 newnode = commitmemorynode(
                     repo,
                     p1,
                     p2,
                     wctx=self.wctx,
                     extra=extra,
                     commitmsg=commitmsg,
                     editor=editor,
                     user=ctx.user(),
                     date=date,
                 )
                 mergemod.mergestate.clean(repo)
             else:
                 newnode = commitnode(
                     repo,
                     p1,
                     p2,
                     extra=extra,
                     commitmsg=commitmsg,
                     editor=editor,
                     user=ctx.user(),
                     date=date,
                 )
 
             if newnode is None:
                 # If it ended up being a no-op commit, then the normal
                 # merge state clean-up path doesn't happen, so do it
                 # here. Fix issue5494
                 mergemod.mergestate.clean(repo)
             return newnode
 
     def _rebasenode(self, tr, rev, allowdivergence, progressfn):
         repo, ui, opts = self.repo, self.ui, self.opts
         dest = self.destmap[rev]
         ctx = repo[rev]
         desc = _ctxdesc(ctx)
         if self.state[rev] == rev:
             ui.status(_(b'already rebased %s\n') % desc)
         elif (
             not allowdivergence
             and rev in self.obsoletewithoutsuccessorindestination
         ):
             msg = (
                 _(
                     b'note: not rebasing %s and its descendants as '
                     b'this would cause divergence\n'
                 )
                 % desc
             )
             repo.ui.status(msg)
             self.skipped.add(rev)
         elif rev in self.obsoletenotrebased:
             succ = self.obsoletenotrebased[rev]
             if succ is None:
                 msg = _(b'note: not rebasing %s, it has no successor\n') % desc
             else:
                 succdesc = _ctxdesc(repo[succ])
                 msg = _(
                     b'note: not rebasing %s, already in destination as %s\n'
                 ) % (desc, succdesc)
             repo.ui.status(msg)
             # Make clearrebased aware state[rev] is not a true successor
             self.skipped.add(rev)
             # Record rev as moved to its desired destination in self.state.
             # This helps bookmark and working parent movement.
             dest = max(
                 adjustdest(repo, rev, self.destmap, self.state, self.skipped)
             )
             self.state[rev] = dest
         elif self.state[rev] == revtodo:
             ui.status(_(b'rebasing %s\n') % desc)
             progressfn(ctx)
             p1, p2, base = defineparents(
                 repo,
                 rev,
                 self.destmap,
                 self.state,
                 self.skipped,
                 self.obsoletenotrebased,
             )
-            if not self.inmemory and len(repo[None].parents()) == 2:
+            if self.resume and self.wctx.p1().rev() == p1:
                 repo.ui.debug(b'resuming interrupted rebase\n')
+                self.resume = False
             else:
                 overrides = {(b'ui', b'forcemerge'): opts.get(b'tool', b'')}
                 with ui.configoverride(overrides, b'rebase'):
                     stats = rebasenode(
                         repo,
                         rev,
                         p1,
                         base,
                         self.collapsef,
                         dest,
                         wctx=self.wctx,
                     )
                     if stats.unresolvedcount > 0:
                         if self.inmemory:
                             raise error.InMemoryMergeConflictsError()
                         else:
                             raise error.InterventionRequired(
                                 _(
                                     b'unresolved conflicts (see hg '
                                     b'resolve, then hg rebase --continue)'
                                 )
                             )
             if not self.collapsef:
                 merging = p2 != nullrev
                 editform = cmdutil.mergeeditform(merging, b'rebase')
                 editor = cmdutil.getcommiteditor(
                     editform=editform, **pycompat.strkwargs(opts)
                 )
                 newnode = self._concludenode(rev, p1, p2, editor)
             else:
                 # Skip commit if we are collapsing
                 if self.inmemory:
                     self.wctx.setbase(repo[p1])
                 else:
                     repo.setparents(repo[p1].node())
                 newnode = None
             # Update the state
             if newnode is not None:
                 self.state[rev] = repo[newnode].rev()
                 ui.debug(b'rebased as %s\n' % short(newnode))
             else:
                 if not self.collapsef:
                     ui.warn(
                         _(
                             b'note: not rebasing %s, its destination already '
                             b'has all its changes\n'
                         )
                         % desc
                     )
                     self.skipped.add(rev)
                 self.state[rev] = p1
                 ui.debug(b'next revision set to %d\n' % p1)
         else:
             ui.status(
                 _(b'already rebased %s as %s\n') % (desc, repo[self.state[rev]])
             )
         if not tr:
             # When not using single transaction, store state after each
             # commit is completely done. On InterventionRequired, we thus
             # won't store the status. Instead, we'll hit the "len(parents) == 2"
             # case and realize that the commit was in progress.
             self.storestatus()
 
     def _finishrebase(self):
         repo, ui, opts = self.repo, self.ui, self.opts
         fm = ui.formatter(b'rebase', opts)
         fm.startitem()
         if self.collapsef:
             p1, p2, _base = defineparents(
                 repo,
                 min(self.state),
                 self.destmap,
                 self.state,
                 self.skipped,
                 self.obsoletenotrebased,
             )
             editopt = opts.get(b'edit')
             editform = b'rebase.collapse'
             if self.collapsemsg:
                 commitmsg = self.collapsemsg
             else:
                 commitmsg = b'Collapsed revision'
                 for rebased in sorted(self.state):
                     if rebased not in self.skipped:
                         commitmsg += b'\n* %s' % repo[rebased].description()
                 editopt = True
             editor = cmdutil.getcommiteditor(edit=editopt, editform=editform)
             revtoreuse = max(self.state)
 
             newnode = self._concludenode(
                 revtoreuse, p1, self.external, editor, commitmsg=commitmsg
             )
 
             if newnode is not None:
                 newrev = repo[newnode].rev()
                 for oldrev in self.state:
                     self.state[oldrev] = newrev
 
         if b'qtip' in repo.tags():
             updatemq(repo, self.state, self.skipped, **pycompat.strkwargs(opts))
 
         # restore original working directory
         # (we do this before stripping)
         newwd = self.state.get(self.originalwd, self.originalwd)
         if newwd < 0:
             # original directory is a parent of rebase set root or ignored
             newwd = self.originalwd
         if newwd not in [c.rev() for c in repo[None].parents()]:
             ui.note(_(b"update back to initial working directory parent\n"))
             hg.updaterepo(repo, newwd, overwrite=False)
 
         collapsedas = None
         if self.collapsef and not self.keepf:
             collapsedas = newnode
         clearrebased(
             ui,
             repo,
             self.destmap,
             self.state,
             self.skipped,
             collapsedas,
             self.keepf,
             fm=fm,
             backup=self.backupf,
         )
 
         clearstatus(repo)
         clearcollapsemsg(repo)
 
         ui.note(_(b"rebase completed\n"))
         util.unlinkpath(repo.sjoin(b'undo'), ignoremissing=True)
         if self.skipped:
             skippedlen = len(self.skipped)
             ui.note(_(b"%d revisions have been skipped\n") % skippedlen)
         fm.end()
 
         if (
             self.activebookmark
             and self.activebookmark in repo._bookmarks
             and repo[b'.'].node() == repo._bookmarks[self.activebookmark]
         ):
             bookmarks.activate(repo, self.activebookmark)
 
     def _abort(self, backup=True, suppwarns=False):
         '''Restore the repository to its original state.'''
 
         repo = self.repo
         try:
             # If the first commits in the rebased set get skipped during the
             # rebase, their values within the state mapping will be the dest
             # rev id. The rebased list must must not contain the dest rev
             # (issue4896)
             rebased = [
                 s
                 for r, s in self.state.items()
                 if s >= 0 and s != r and s != self.destmap[r]
             ]
             immutable = [d for d in rebased if not repo[d].mutable()]
             cleanup = True
             if immutable:
                 repo.ui.warn(
                     _(b"warning: can't clean up public changesets %s\n")
                     % b', '.join(bytes(repo[r]) for r in immutable),
                     hint=_(b"see 'hg help phases' for details"),
                 )
                 cleanup = False
 
             descendants = set()
             if rebased:
                 descendants = set(repo.changelog.descendants(rebased))
             if descendants - set(rebased):
                 repo.ui.warn(
                     _(
                         b"warning: new changesets detected on "
                         b"destination branch, can't strip\n"
                     )
                 )
                 cleanup = False
 
             if cleanup:
                 if rebased:
                     strippoints = [
                         c.node() for c in repo.set(b'roots(%ld)', rebased)
                     ]
 
                 updateifonnodes = set(rebased)
                 updateifonnodes.update(self.destmap.values())
                 updateifonnodes.add(self.originalwd)
                 shouldupdate = repo[b'.'].rev() in updateifonnodes
 
                 # Update away from the rebase if necessary
                 if shouldupdate:
                     mergemod.clean_update(repo[self.originalwd])
 
                 # Strip from the first rebased revision
                 if rebased:
                     repair.strip(repo.ui, repo, strippoints, backup=backup)
 
             if self.activebookmark and self.activebookmark in repo._bookmarks:
                 bookmarks.activate(repo, self.activebookmark)
 
         finally:
             clearstatus(repo)
             clearcollapsemsg(repo)
             if not suppwarns:
                 repo.ui.warn(_(b'rebase aborted\n'))
         return 0
 
 
 @command(
     b'rebase',
     [
         (
             b's',
             b'source',
             b'',
             _(b'rebase the specified changeset and descendants'),
             _(b'REV'),
         ),
         (
             b'b',
             b'base',
             b'',
             _(b'rebase everything from branching point of specified changeset'),
             _(b'REV'),
         ),
         (b'r', b'rev', [], _(b'rebase these revisions'), _(b'REV')),
         (
             b'd',
             b'dest',
             b'',
             _(b'rebase onto the specified changeset'),
             _(b'REV'),
         ),
         (b'', b'collapse', False, _(b'collapse the rebased changesets')),
         (
             b'm',
             b'message',
             b'',
             _(b'use text as collapse commit message'),
             _(b'TEXT'),
         ),
         (b'e', b'edit', False, _(b'invoke editor on commit messages')),
         (
             b'l',
             b'logfile',
             b'',
             _(b'read collapse commit message from file'),
             _(b'FILE'),
         ),
         (b'k', b'keep', False, _(b'keep original changesets')),
         (b'', b'keepbranches', False, _(b'keep original branch names')),
         (b'D', b'detach', False, _(b'(DEPRECATED)')),
         (b'i', b'interactive', False, _(b'(DEPRECATED)')),
         (b't', b'tool', b'', _(b'specify merge tool')),
         (b'', b'stop', False, _(b'stop interrupted rebase')),
         (b'c', b'continue', False, _(b'continue an interrupted rebase')),
         (b'a', b'abort', False, _(b'abort an interrupted rebase')),
         (
             b'',
             b'auto-orphans',
             b'',
             _(
                 b'automatically rebase orphan revisions '
                 b'in the specified revset (EXPERIMENTAL)'
             ),
         ),
     ]
     + cmdutil.dryrunopts
     + cmdutil.formatteropts
     + cmdutil.confirmopts,
     _(b'[-s REV | -b REV] [-d REV] [OPTION]'),
     helpcategory=command.CATEGORY_CHANGE_MANAGEMENT,
 )
 def rebase(ui, repo, **opts):
     """move changeset (and descendants) to a different branch
 
     Rebase uses repeated merging to graft changesets from one part of
     history (the source) onto another (the destination). This can be
     useful for linearizing *local* changes relative to a master
     development tree.
 
     Published commits cannot be rebased (see :hg:`help phases`).
     To copy commits, see :hg:`help graft`.
 
     If you don't specify a destination changeset (``-d/--dest``), rebase
     will use the same logic as :hg:`merge` to pick a destination.  if
     the current branch contains exactly one other head, the other head
     is merged with by default.  Otherwise, an explicit revision with
     which to merge with must be provided.  (destination changeset is not
     modified by rebasing, but new changesets are added as its
     descendants.)
 
     Here are the ways to select changesets:
 
       1. Explicitly select them using ``--rev``.
 
       2. Use ``--source`` to select a root changeset and include all of its
          descendants.
 
       3. Use ``--base`` to select a changeset; rebase will find ancestors
          and their descendants which are not also ancestors of the destination.
 
       4. If you do not specify any of ``--rev``, ``--source``, or ``--base``,
          rebase will use ``--base .`` as above.
 
     If ``--source`` or ``--rev`` is used, special names ``SRC`` and ``ALLSRC``
     can be used in ``--dest``. Destination would be calculated per source
     revision with ``SRC`` substituted by that single source revision and
     ``ALLSRC`` substituted by all source revisions.
 
     Rebase will destroy original changesets unless you use ``--keep``.
     It will also move your bookmarks (even if you do).
 
     Some changesets may be dropped if they do not contribute changes
     (e.g. merges from the destination branch).
 
     Unlike ``merge``, rebase will do nothing if you are at the branch tip of
     a named branch with two heads. You will need to explicitly specify source
     and/or destination.
 
     If you need to use a tool to automate merge/conflict decisions, you
     can specify one with ``--tool``, see :hg:`help merge-tools`.
     As a caveat: the tool will not be used to mediate when a file was
     deleted, there is no hook presently available for this.
 
     If a rebase is interrupted to manually resolve a conflict, it can be
     continued with --continue/-c, aborted with --abort/-a, or stopped with
     --stop.
 
     .. container:: verbose
 
       Examples:
 
       - move "local changes" (current commit back to branching point)
         to the current branch tip after a pull::
 
           hg rebase
 
       - move a single changeset to the stable branch::
 
           hg rebase -r 5f493448 -d stable
 
       - splice a commit and all its descendants onto another part of history::
 
           hg rebase --source c0c3 --dest 4cf9
 
       - rebase everything on a branch marked by a bookmark onto the
         default branch::
 
           hg rebase --base myfeature --dest default
 
       - collapse a sequence of changes into a single commit::
 
           hg rebase --collapse -r 1520:1525 -d .
 
       - move a named branch while preserving its name::
 
           hg rebase -r "branch(featureX)" -d 1.3 --keepbranches
 
       - stabilize orphaned changesets so history looks linear::
 
           hg rebase -r 'orphan()-obsolete()'\
  -d 'first(max((successors(max(roots(ALLSRC) & ::SRC)^)-obsolete())::) +\
  max(::((roots(ALLSRC) & ::SRC)^)-obsolete()))'
 
     Configuration Options:
 
     You can make rebase require a destination if you set the following config
     option::
 
       [commands]
       rebase.requiredest = True
 
     By default, rebase will close the transaction after each commit. For
     performance purposes, you can configure rebase to use a single transaction
     across the entire rebase. WARNING: This setting introduces a significant
     risk of losing the work you've done in a rebase if the rebase aborts
     unexpectedly::
 
       [rebase]
       singletransaction = True
 
     By default, rebase writes to the working copy, but you can configure it to
     run in-memory for better performance. When the rebase is not moving the
     parent(s) of the working copy (AKA the "currently checked out changesets"),
     this may also allow it to run even if the working copy is dirty::
 
       [rebase]
       experimental.inmemory = True
 
     Return Values:
 
     Returns 0 on success, 1 if nothing to rebase or there are
     unresolved conflicts.
 
     """
     opts = pycompat.byteskwargs(opts)
     inmemory = ui.configbool(b'rebase', b'experimental.inmemory')
     action = cmdutil.check_at_most_one_arg(opts, b'abort', b'stop', b'continue')
     if action:
         cmdutil.check_incompatible_arguments(
             opts, action, [b'confirm', b'dry_run']
         )
         cmdutil.check_incompatible_arguments(
             opts, action, [b'rev', b'source', b'base', b'dest']
         )
     cmdutil.check_at_most_one_arg(opts, b'confirm', b'dry_run')
     cmdutil.check_at_most_one_arg(opts, b'rev', b'source', b'base')
 
     if action or repo.currenttransaction() is not None:
         # in-memory rebase is not compatible with resuming rebases.
         # (Or if it is run within a transaction, since the restart logic can
         # fail the entire transaction.)
         inmemory = False
 
     if opts.get(b'auto_orphans'):
         disallowed_opts = set(opts) - {b'auto_orphans'}
         cmdutil.check_incompatible_arguments(
             opts, b'auto_orphans', disallowed_opts
         )
 
         userrevs = list(repo.revs(opts.get(b'auto_orphans')))
         opts[b'rev'] = [revsetlang.formatspec(b'%ld and orphan()', userrevs)]
         opts[b'dest'] = b'_destautoorphanrebase(SRC)'
 
     if opts.get(b'dry_run') or opts.get(b'confirm'):
         return _dryrunrebase(ui, repo, action, opts)
     elif action == b'stop':
         rbsrt = rebaseruntime(repo, ui)
         with repo.wlock(), repo.lock():
             rbsrt.restorestatus()
             if rbsrt.collapsef:
                 raise error.Abort(_(b"cannot stop in --collapse session"))
             allowunstable = obsolete.isenabled(repo, obsolete.allowunstableopt)
             if not (rbsrt.keepf or allowunstable):
                 raise error.Abort(
                     _(
                         b"cannot remove original changesets with"
                         b" unrebased descendants"
                     ),
                     hint=_(
                         b'either enable obsmarkers to allow unstable '
                         b'revisions or use --keep to keep original '
                         b'changesets'
                     ),
                 )
             # update to the current working revision
             # to clear interrupted merge
             hg.updaterepo(repo, rbsrt.originalwd, overwrite=True)
             rbsrt._finishrebase()
             return 0
     elif inmemory:
         try:
             # in-memory merge doesn't support conflicts, so if we hit any, abort
             # and re-run as an on-disk merge.
             overrides = {(b'rebase', b'singletransaction'): True}
             with ui.configoverride(overrides, b'rebase'):
                 return _dorebase(ui, repo, action, opts, inmemory=inmemory)
         except error.InMemoryMergeConflictsError:
             ui.warn(
                 _(
                     b'hit merge conflicts; re-running rebase without in-memory'
                     b' merge\n'
                 )
             )
             # TODO: Make in-memory merge not use the on-disk merge state, so
             # we don't have to clean it here
             mergemod.mergestate.clean(repo)
             clearstatus(repo)
             clearcollapsemsg(repo)
             return _dorebase(ui, repo, action, opts, inmemory=False)
     else:
         return _dorebase(ui, repo, action, opts)
 
 
 def _dryrunrebase(ui, repo, action, opts):
     rbsrt = rebaseruntime(repo, ui, inmemory=True, opts=opts)
     confirm = opts.get(b'confirm')
     if confirm:
         ui.status(_(b'starting in-memory rebase\n'))
     else:
         ui.status(
             _(b'starting dry-run rebase; repository will not be changed\n')
         )
     with repo.wlock(), repo.lock():
         needsabort = True
         try:
             overrides = {(b'rebase', b'singletransaction'): True}
             with ui.configoverride(overrides, b'rebase'):
                 _origrebase(
                     ui,
                     repo,
                     action,
                     opts,
                     rbsrt,
                     inmemory=True,
                     leaveunfinished=True,
                 )
         except error.InMemoryMergeConflictsError:
             ui.status(_(b'hit a merge conflict\n'))
             return 1
         except error.Abort:
             needsabort = False
             raise
         else:
             if confirm:
                 ui.status(_(b'rebase completed successfully\n'))
                 if not ui.promptchoice(_(b'apply changes (yn)?$$ &Yes $$ &No')):
                     # finish unfinished rebase
                     rbsrt._finishrebase()
                 else:
                     rbsrt._prepareabortorcontinue(
                         isabort=True, backup=False, suppwarns=True
                     )
                 needsabort = False
             else:
                 ui.status(
                     _(
                         b'dry-run rebase completed successfully; run without'
                         b' -n/--dry-run to perform this rebase\n'
                     )
                 )
             return 0
         finally:
             if needsabort:
                 # no need to store backup in case of dryrun
                 rbsrt._prepareabortorcontinue(
                     isabort=True, backup=False, suppwarns=True
                 )
 
 
 def _dorebase(ui, repo, action, opts, inmemory=False):
     rbsrt = rebaseruntime(repo, ui, inmemory, opts)
     return _origrebase(ui, repo, action, opts, rbsrt, inmemory=inmemory)
 
 
 def _origrebase(
     ui, repo, action, opts, rbsrt, inmemory=False, leaveunfinished=False
 ):
     assert action != b'stop'
     with repo.wlock(), repo.lock():
         if opts.get(b'interactive'):
             try:
                 if extensions.find(b'histedit'):
                     enablehistedit = b''
             except KeyError:
                 enablehistedit = b" --config extensions.histedit="
             help = b"hg%s help -e histedit" % enablehistedit
             msg = (
                 _(
                     b"interactive history editing is supported by the "
                     b"'histedit' extension (see \"%s\")"
                 )
                 % help
             )
             raise error.Abort(msg)
 
         if rbsrt.collapsemsg and not rbsrt.collapsef:
             raise error.Abort(_(b'message can only be specified with collapse'))
 
         if action:
             if rbsrt.collapsef:
                 raise error.Abort(
                     _(b'cannot use collapse with continue or abort')
                 )
             if action == b'abort' and opts.get(b'tool', False):
                 ui.warn(_(b'tool option will be ignored\n'))
             if action == b'continue':
                 ms = mergemod.mergestate.read(repo)
                 mergeutil.checkunresolved(ms)
 
             retcode = rbsrt._prepareabortorcontinue(
                 isabort=(action == b'abort')
             )
             if retcode is not None:
                 return retcode
         else:
             # search default destination in this space
             # used in the 'hg pull --rebase' case, see issue 5214.
             destspace = opts.get(b'_destspace')
             destmap = _definedestmap(
                 ui,
                 repo,
                 inmemory,
                 opts.get(b'dest', None),
                 opts.get(b'source', None),
                 opts.get(b'base', None),
                 opts.get(b'rev', []),
                 destspace=destspace,
             )
             retcode = rbsrt._preparenewrebase(destmap)
             if retcode is not None:
                 return retcode
             storecollapsemsg(repo, rbsrt.collapsemsg)
 
         tr = None
 
         singletr = ui.configbool(b'rebase', b'singletransaction')
         if singletr:
             tr = repo.transaction(b'rebase')
 
         # If `rebase.singletransaction` is enabled, wrap the entire operation in
         # one transaction here. Otherwise, transactions are obtained when
         # committing each node, which is slower but allows partial success.
         with util.acceptintervention(tr):
             # Same logic for the dirstate guard, except we don't create one when
             # rebasing in-memory (it's not needed).
             dsguard = None
             if singletr and not inmemory:
                 dsguard = dirstateguard.dirstateguard(repo, b'rebase')
             with util.acceptintervention(dsguard):
                 rbsrt._performrebase(tr)
                 if not leaveunfinished:
                     rbsrt._finishrebase()
 
 
 def _definedestmap(
     ui,
     repo,
     inmemory,
     destf=None,
     srcf=None,
     basef=None,
     revf=None,
     destspace=None,
 ):
     """use revisions argument to define destmap {srcrev: destrev}"""
     if revf is None:
         revf = []
 
     # destspace is here to work around issues with `hg pull --rebase` see
     # issue5214 for details
 
     cmdutil.checkunfinished(repo)
     if not inmemory:
         cmdutil.bailifchanged(repo)
 
     if ui.configbool(b'commands', b'rebase.requiredest') and not destf:
         raise error.Abort(
             _(b'you must specify a destination'),
             hint=_(b'use: hg rebase -d REV'),
         )
 
     dest = None
 
     if revf:
         rebaseset = scmutil.revrange(repo, revf)
         if not rebaseset:
             ui.status(_(b'empty "rev" revision set - nothing to rebase\n'))
             return None
     elif srcf:
         src = scmutil.revrange(repo, [srcf])
         if not src:
             ui.status(_(b'empty "source" revision set - nothing to rebase\n'))
             return None
         rebaseset = repo.revs(b'(%ld)::', src) or src
     else:
         base = scmutil.revrange(repo, [basef or b'.'])
         if not base:
             ui.status(
                 _(b'empty "base" revision set - ' b"can't compute rebase set\n")
             )
             return None
         if destf:
             # --base does not support multiple destinations
             dest = scmutil.revsingle(repo, destf)
         else:
             dest = repo[_destrebase(repo, base, destspace=destspace)]
             destf = bytes(dest)
 
         roots = []  # selected children of branching points
         bpbase = {}  # {branchingpoint: [origbase]}
         for b in base:  # group bases by branching points
             bp = repo.revs(b'ancestor(%d, %d)', b, dest.rev()).first()
             bpbase[bp] = bpbase.get(bp, []) + [b]
         if None in bpbase:
             # emulate the old behavior, showing "nothing to rebase" (a better
             # behavior may be abort with "cannot find branching point" error)
             bpbase.clear()
         for bp, bs in pycompat.iteritems(bpbase):  # calculate roots
             roots += list(repo.revs(b'children(%d) & ancestors(%ld)', bp, bs))
 
         rebaseset = repo.revs(b'%ld::', roots)
 
         if not rebaseset:
             # transform to list because smartsets are not comparable to
             # lists. This should be improved to honor laziness of
             # smartset.
             if list(base) == [dest.rev()]:
                 if basef:
                     ui.status(
                         _(
                             b'nothing to rebase - %s is both "base"'
                             b' and destination\n'
                         )
                         % dest
                     )
                 else:
                     ui.status(
                         _(
                             b'nothing to rebase - working directory '
                             b'parent is also destination\n'
                         )
                     )
             elif not repo.revs(b'%ld - ::%d', base, dest.rev()):
                 if basef:
                     ui.status(
                         _(
                             b'nothing to rebase - "base" %s is '
                             b'already an ancestor of destination '
                             b'%s\n'
                         )
                         % (b'+'.join(bytes(repo[r]) for r in base), dest)
                     )
                 else:
                     ui.status(
                         _(
                             b'nothing to rebase - working '
                             b'directory parent is already an '
                             b'ancestor of destination %s\n'
                         )
                         % dest
                     )
             else:  # can it happen?
                 ui.status(
                     _(b'nothing to rebase from %s to %s\n')
                     % (b'+'.join(bytes(repo[r]) for r in base), dest)
                 )
             return None
 
     if nodemod.wdirrev in rebaseset:
         raise error.Abort(_(b'cannot rebase the working copy'))
     rebasingwcp = repo[b'.'].rev() in rebaseset
     ui.log(
         b"rebase",
         b"rebasing working copy parent: %r\n",
         rebasingwcp,
         rebase_rebasing_wcp=rebasingwcp,
     )
     if inmemory and rebasingwcp:
         # Check these since we did not before.
         cmdutil.checkunfinished(repo)
         cmdutil.bailifchanged(repo)
 
     if not destf:
         dest = repo[_destrebase(repo, rebaseset, destspace=destspace)]
         destf = bytes(dest)
 
     allsrc = revsetlang.formatspec(b'%ld', rebaseset)
     alias = {b'ALLSRC': allsrc}
 
     if dest is None:
         try:
             # fast path: try to resolve dest without SRC alias
             dest = scmutil.revsingle(repo, destf, localalias=alias)
         except error.RepoLookupError:
             # multi-dest path: resolve dest for each SRC separately
             destmap = {}
             for r in rebaseset:
                 alias[b'SRC'] = revsetlang.formatspec(b'%d', r)
                 # use repo.anyrevs instead of scmutil.revsingle because we
                 # don't want to abort if destset is empty.
                 destset = repo.anyrevs([destf], user=True, localalias=alias)
                 size = len(destset)
                 if size == 1:
                     destmap[r] = destset.first()
                 elif size == 0:
                     ui.note(_(b'skipping %s - empty destination\n') % repo[r])
                 else:
                     raise error.Abort(
                         _(b'rebase destination for %s is not unique') % repo[r]
                     )
 
     if dest is not None:
         # single-dest case: assign dest to each rev in rebaseset
         destrev = dest.rev()
         destmap = {r: destrev for r in rebaseset}  # {srcrev: destrev}
 
     if not destmap:
         ui.status(_(b'nothing to rebase - empty destination\n'))
         return None
 
     return destmap
 
 
 def externalparent(repo, state, destancestors):
     """Return the revision that should be used as the second parent
     when the revisions in state is collapsed on top of destancestors.
     Abort if there is more than one parent.
     """
     parents = set()
     source = min(state)
     for rev in state:
         if rev == source:
             continue
         for p in repo[rev].parents():
             if p.rev() not in state and p.rev() not in destancestors:
                 parents.add(p.rev())
     if not parents:
         return nullrev
     if len(parents) == 1:
         return parents.pop()
     raise error.Abort(
         _(
             b'unable to collapse on top of %d, there is more '
             b'than one external parent: %s'
         )
         % (max(destancestors), b', '.join(b"%d" % p for p in sorted(parents)))
     )
 
 
 def commitmemorynode(repo, p1, p2, wctx, editor, extra, user, date, commitmsg):
     '''Commit the memory changes with parents p1 and p2.
     Return node of committed revision.'''
     # Replicates the empty check in ``repo.commit``.
     if wctx.isempty() and not repo.ui.configbool(b'ui', b'allowemptycommit'):
         return None
 
     # By convention, ``extra['branch']`` (set by extrafn) clobbers
     # ``branch`` (used when passing ``--keepbranches``).
     branch = None
     if b'branch' in extra:
         branch = extra[b'branch']
 
     wctx.setparents(repo[p1].node(), repo[p2].node())
     memctx = wctx.tomemctx(
         commitmsg,
         date=date,
         extra=extra,
         user=user,
         branch=branch,
         editor=editor,
     )
     commitres = repo.commitctx(memctx)
     wctx.clean()  # Might be reused
     return commitres
 
 
 def commitnode(repo, p1, p2, editor, extra, user, date, commitmsg):
     '''Commit the wd changes with parents p1 and p2.
     Return node of committed revision.'''
     dsguard = util.nullcontextmanager()
     if not repo.ui.configbool(b'rebase', b'singletransaction'):
         dsguard = dirstateguard.dirstateguard(repo, b'rebase')
     with dsguard:
         repo.setparents(repo[p1].node(), repo[p2].node())
 
         # Commit might fail if unresolved files exist
         newnode = repo.commit(
             text=commitmsg, user=user, date=date, extra=extra, editor=editor
         )
 
         repo.dirstate.setbranch(repo[newnode].branch())
         return newnode
 
 
 def rebasenode(repo, rev, p1, base, collapse, dest, wctx):
     """Rebase a single revision rev on top of p1 using base as merge ancestor"""
     # Merge phase
     # Update to destination and merge it with local
     p1ctx = repo[p1]
     if wctx.isinmemory():
         wctx.setbase(p1ctx)
     else:
         if repo[b'.'].rev() != p1:
             repo.ui.debug(b" update to %d:%s\n" % (p1, p1ctx))
             mergemod.clean_update(p1ctx)
         else:
             repo.ui.debug(b" already in destination\n")
         # This is, alas, necessary to invalidate workingctx's manifest cache,
         # as well as other data we litter on it in other places.
         wctx = repo[None]
         repo.dirstate.write(repo.currenttransaction())
     ctx = repo[rev]
     repo.ui.debug(b" merge against %d:%s\n" % (rev, ctx))
     if base is not None:
         repo.ui.debug(b"   detach base %d:%s\n" % (base, repo[base]))
 
     # See explanation in merge.graft()
     mergeancestor = repo.changelog.isancestor(p1ctx.node(), ctx.node())
     stats = mergemod.update(
         repo,
         rev,
         branchmerge=True,
         force=True,
         ancestor=base,
         mergeancestor=mergeancestor,
         labels=[b'dest', b'source'],
         wc=wctx,
     )
     if collapse:
         copies.graftcopies(wctx, ctx, repo[dest])
     else:
         # If we're not using --collapse, we need to
         # duplicate copies between the revision we're
         # rebasing and its first parent.
         copies.graftcopies(wctx, ctx, ctx.p1())
     return stats
 
 
 def adjustdest(repo, rev, destmap, state, skipped):
     r"""adjust rebase destination given the current rebase state
 
     rev is what is being rebased. Return a list of two revs, which are the
     adjusted destinations for rev's p1 and p2, respectively. If a parent is
     nullrev, return dest without adjustment for it.
 
     For example, when doing rebasing B+E to F, C to G, rebase will first move B
     to B1, and E's destination will be adjusted from F to B1.
 
         B1 <- written during rebasing B
         |
         F <- original destination of B, E
         |
         | E <- rev, which is being rebased
         | |
         | D <- prev, one parent of rev being checked
         | |
         | x <- skipped, ex. no successor or successor in (::dest)
         | |
         | C <- rebased as C', different destination
         | |
         | B <- rebased as B1     C'
         |/                       |
         A                        G <- destination of C, different
 
     Another example about merge changeset, rebase -r C+G+H -d K, rebase will
     first move C to C1, G to G1, and when it's checking H, the adjusted
     destinations will be [C1, G1].
 
             H       C1 G1
            /|       | /
           F G       |/
         K | |  ->   K
         | C D       |
         | |/        |
         | B         | ...
         |/          |/
         A           A
 
     Besides, adjust dest according to existing rebase information. For example,
 
       B C D    B needs to be rebased on top of C, C needs to be rebased on top
        \|/     of D. We will rebase C first.
         A
 
           C'   After rebasing C, when considering B's destination, use C'
           |    instead of the original C.
       B   D
        \ /
         A
     """
     # pick already rebased revs with same dest from state as interesting source
     dest = destmap[rev]
     source = [
         s
         for s, d in state.items()
         if d > 0 and destmap[s] == dest and s not in skipped
     ]
 
     result = []
     for prev in repo.changelog.parentrevs(rev):
         adjusted = dest
         if prev != nullrev:
             candidate = repo.revs(b'max(%ld and (::%d))', source, prev).first()
             if candidate is not None:
                 adjusted = state[candidate]
         if adjusted == dest and dest in state:
             adjusted = state[dest]
             if adjusted == revtodo:
                 # sortsource should produce an order that makes this impossible
                 raise error.ProgrammingError(
                     b'rev %d should be rebased already at this time' % dest
                 )
         result.append(adjusted)
     return result
 
 
 def _checkobsrebase(repo, ui, rebaseobsrevs, rebaseobsskipped):
     """
     Abort if rebase will create divergence or rebase is noop because of markers
 
     `rebaseobsrevs`: set of obsolete revision in source
     `rebaseobsskipped`: set of revisions from source skipped because they have
     successors in destination or no non-obsolete successor.
     """
     # Obsolete node with successors not in dest leads to divergence
     divergenceok = ui.configbool(b'experimental', b'evolution.allowdivergence')
     divergencebasecandidates = rebaseobsrevs - rebaseobsskipped
 
     if divergencebasecandidates and not divergenceok:
         divhashes = (bytes(repo[r]) for r in divergencebasecandidates)
         msg = _(b"this rebase will cause divergences from: %s")
         h = _(
             b"to force the rebase please set "
             b"experimental.evolution.allowdivergence=True"
         )
         raise error.Abort(msg % (b",".join(divhashes),), hint=h)
 
 
 def successorrevs(unfi, rev):
     """yield revision numbers for successors of rev"""
     assert unfi.filtername is None
     get_rev = unfi.changelog.index.get_rev
     for s in obsutil.allsuccessors(unfi.obsstore, [unfi[rev].node()]):
         r = get_rev(s)
         if r is not None:
             yield r
 
 
 def defineparents(repo, rev, destmap, state, skipped, obsskipped):
     """Return new parents and optionally a merge base for rev being rebased
 
     The destination specified by "dest" cannot always be used directly because
     previously rebase result could affect destination. For example,
 
           D E    rebase -r C+D+E -d B
           |/     C will be rebased to C'
         B C      D's new destination will be C' instead of B
         |/       E's new destination will be C' instead of B
         A
 
     The new parents of a merge is slightly more complicated. See the comment
     block below.
     """
     # use unfiltered changelog since successorrevs may return filtered nodes
     assert repo.filtername is None
     cl = repo.changelog
     isancestor = cl.isancestorrev
 
     dest = destmap[rev]
     oldps = repo.changelog.parentrevs(rev)  # old parents
     newps = [nullrev, nullrev]  # new parents
     dests = adjustdest(repo, rev, destmap, state, skipped)
     bases = list(oldps)  # merge base candidates, initially just old parents
 
     if all(r == nullrev for r in oldps[1:]):
         # For non-merge changeset, just move p to adjusted dest as requested.
         newps[0] = dests[0]
     else:
         # For merge changeset, if we move p to dests[i] unconditionally, both
         # parents may change and the end result looks like "the merge loses a
         # parent", which is a surprise. This is a limit because "--dest" only
         # accepts one dest per src.
         #
         # Therefore, only move p with reasonable conditions (in this order):
         #   1. use dest, if dest is a descendent of (p or one of p's successors)
         #   2. use p's rebased result, if p is rebased (state[p] > 0)
         #
         # Comparing with adjustdest, the logic here does some additional work:
         #   1. decide which parents will not be moved towards dest
         #   2. if the above decision is "no", should a parent still be moved
         #      because it was rebased?
         #
         # For example:
         #
         #     C    # "rebase -r C -d D" is an error since none of the parents
         #    /|    # can be moved. "rebase -r B+C -d D" will move C's parent
         #   A B D  # B (using rule "2."), since B will be rebased.
         #
         # The loop tries to be not rely on the fact that a Mercurial node has
         # at most 2 parents.
         for i, p in enumerate(oldps):
             np = p  # new parent
             if any(isancestor(x, dests[i]) for x in successorrevs(repo, p)):
                 np = dests[i]
             elif p in state and state[p] > 0:
                 np = state[p]
 
             # If one parent becomes an ancestor of the other, drop the ancestor
             for j, x in enumerate(newps[:i]):
                 if x == nullrev:
                     continue
                 if isancestor(np, x):  # CASE-1
                     np = nullrev
                 elif isancestor(x, np):  # CASE-2
                     newps[j] = np
                     np = nullrev
                     # New parents forming an ancestor relationship does not
                     # mean the old parents have a similar relationship. Do not
                     # set bases[x] to nullrev.
                     bases[j], bases[i] = bases[i], bases[j]
 
             newps[i] = np
 
         # "rebasenode" updates to new p1, and the old p1 will be used as merge
         # base. If only p2 changes, merging using unchanged p1 as merge base is
         # suboptimal. Therefore swap parents to make the merge sane.
         if newps[1] != nullrev and oldps[0] == newps[0]:
             assert len(newps) == 2 and len(oldps) == 2
             newps.reverse()
             bases.reverse()
 
         # No parent change might be an error because we fail to make rev a
         # descendent of requested dest. This can happen, for example:
         #
         #     C    # rebase -r C -d D
         #    /|    # None of A and B will be changed to D and rebase fails.
         #   A B D
         if set(newps) == set(oldps) and dest not in newps:
             raise error.Abort(
                 _(
                     b'cannot rebase %d:%s without '
                     b'moving at least one of its parents'
                 )
                 % (rev, repo[rev])
             )
 
     # Source should not be ancestor of dest. The check here guarantees it's
     # impossible. With multi-dest, the initial check does not cover complex
     # cases since we don't have abstractions to dry-run rebase cheaply.
     if any(p != nullrev and isancestor(rev, p) for p in newps):
         raise error.Abort(_(b'source is ancestor of destination'))
 
     # Check if the merge will contain unwanted changes. That may happen if
     # there are multiple special (non-changelog ancestor) merge bases, which
     # cannot be handled well by the 3-way merge algorithm. For example:
     #
     #     F
     #    /|
     #   D E  # "rebase -r D+E+F -d Z", when rebasing F, if "D" was chosen
     #   | |  # as merge base, the difference between D and F will include
     #   B C  # C, so the rebased F will contain C surprisingly. If "E" was
     #   |/   #  chosen, the rebased F will contain B.
     #   A Z
     #
     # But our merge base candidates (D and E in above case) could still be
     # better than the default (ancestor(F, Z) == null). Therefore still
     # pick one (so choose p1 above).
     if sum(1 for b in set(bases) if b != nullrev and b not in newps) > 1:
         unwanted = [None, None]  # unwanted[i]: unwanted revs if choose bases[i]
         for i, base in enumerate(bases):
             if base == nullrev or base in newps:
                 continue
             # Revisions in the side (not chosen as merge base) branch that
             # might contain "surprising" contents
             other_bases = set(bases) - {base}
             siderevs = list(
                 repo.revs(b'(%ld %% (%d+%d))', other_bases, base, dest)
             )
 
             # If those revisions are covered by rebaseset, the result is good.
             # A merge in rebaseset would be considered to cover its ancestors.
             if siderevs:
                 rebaseset = [
                     r for r, d in state.items() if d > 0 and r not in obsskipped
                 ]
                 merges = [
                     r for r in rebaseset if cl.parentrevs(r)[1] != nullrev
                 ]
                 unwanted[i] = list(
                     repo.revs(
                         b'%ld - (::%ld) - %ld', siderevs, merges, rebaseset
                     )
                 )
 
         if any(revs is not None for revs in unwanted):
             # Choose a merge base that has a minimal number of unwanted revs.
             l, i = min(
                 (len(revs), i)
                 for i, revs in enumerate(unwanted)
                 if revs is not None
             )
 
             # The merge will include unwanted revisions. Abort now. Revisit this if
             # we have a more advanced merge algorithm that handles multiple bases.
             if l > 0:
                 unwanteddesc = _(b' or ').join(
                     (
                         b', '.join(b'%d:%s' % (r, repo[r]) for r in revs)
                         for revs in unwanted
                         if revs is not None
                     )
                 )
                 raise error.Abort(
                     _(b'rebasing %d:%s will include unwanted changes from %s')
                     % (rev, repo[rev], unwanteddesc)
                 )
 
             # newps[0] should match merge base if possible. Currently, if newps[i]
             # is nullrev, the only case is newps[i] and newps[j] (j < i), one is
             # the other's ancestor. In that case, it's fine to not swap newps here.
             # (see CASE-1 and CASE-2 above)
             if i != 0:
                 if newps[i] != nullrev:
                     newps[0], newps[i] = newps[i], newps[0]
                 bases[0], bases[i] = bases[i], bases[0]
 
     # "rebasenode" updates to new p1, use the corresponding merge base.
     base = bases[0]
 
     repo.ui.debug(b" future parents are %d and %d\n" % tuple(newps))
 
     return newps[0], newps[1], base
 
 
 def isagitpatch(repo, patchname):
     """Return true if the given patch is in git format"""
     mqpatch = os.path.join(repo.mq.path, patchname)
     for line in patch.linereader(open(mqpatch, b'rb')):
         if line.startswith(b'diff --git'):
             return True
     return False
 
 
 def updatemq(repo, state, skipped, **opts):
     """Update rebased mq patches - finalize and then import them"""
     mqrebase = {}
     mq = repo.mq
     original_series = mq.fullseries[:]
     skippedpatches = set()
 
     for p in mq.applied:
         rev = repo[p.node].rev()
         if rev in state:
             repo.ui.debug(
                 b'revision %d is an mq patch (%s), finalize it.\n'
                 % (rev, p.name)
             )
             mqrebase[rev] = (p.name, isagitpatch(repo, p.name))
         else:
             # Applied but not rebased, not sure this should happen
             skippedpatches.add(p.name)
 
     if mqrebase:
         mq.finish(repo, mqrebase.keys())
 
         # We must start import from the newest revision
         for rev in sorted(mqrebase, reverse=True):
             if rev not in skipped:
                 name, isgit = mqrebase[rev]
                 repo.ui.note(
                     _(b'updating mq patch %s to %d:%s\n')
                     % (name, state[rev], repo[state[rev]])
                 )
                 mq.qimport(
                     repo,
                     (),
                     patchname=name,
                     git=isgit,
                     rev=[b"%d" % state[rev]],
                 )
             else:
                 # Rebased and skipped
                 skippedpatches.add(mqrebase[rev][0])
 
         # Patches were either applied and rebased and imported in
         # order, applied and removed or unapplied. Discard the removed
         # ones while preserving the original series order and guards.
         newseries = [
             s
             for s in original_series
             if mq.guard_re.split(s, 1)[0] not in skippedpatches
         ]
         mq.fullseries[:] = newseries
         mq.seriesdirty = True
         mq.savedirty()
 
 
 def storecollapsemsg(repo, collapsemsg):
     """Store the collapse message to allow recovery"""
     collapsemsg = collapsemsg or b''
     f = repo.vfs(b"last-message.txt", b"w")
     f.write(b"%s\n" % collapsemsg)
     f.close()
 
 
 def clearcollapsemsg(repo):
     """Remove collapse message file"""
     repo.vfs.unlinkpath(b"last-message.txt", ignoremissing=True)
 
 
 def restorecollapsemsg(repo, isabort):
     """Restore previously stored collapse message"""
     try:
         f = repo.vfs(b"last-message.txt")
         collapsemsg = f.readline().strip()
         f.close()
     except IOError as err:
         if err.errno != errno.ENOENT:
             raise
         if isabort:
             # Oh well, just abort like normal
             collapsemsg = b''
         else:
             raise error.Abort(_(b'missing .hg/last-message.txt for rebase'))
     return collapsemsg
 
 
 def clearstatus(repo):
     """Remove the status files"""
     # Make sure the active transaction won't write the state file
     tr = repo.currenttransaction()
     if tr:
         tr.removefilegenerator(b'rebasestate')
     repo.vfs.unlinkpath(b"rebasestate", ignoremissing=True)
 
 
 def sortsource(destmap):
     """yield source revisions in an order that we only rebase things once
 
     If source and destination overlaps, we should filter out revisions
     depending on other revisions which hasn't been rebased yet.
 
     Yield a sorted list of revisions each time.
 
     For example, when rebasing A to B, B to C. This function yields [B], then
     [A], indicating B needs to be rebased first.
 
     Raise if there is a cycle so the rebase is impossible.
     """
     srcset = set(destmap)
     while srcset:
         srclist = sorted(srcset)
         result = []
         for r in srclist:
             if destmap[r] not in srcset:
                 result.append(r)
         if not result:
             raise error.Abort(_(b'source and destination form a cycle'))
         srcset -= set(result)
         yield result
 
 
 def buildstate(repo, destmap, collapse):
     '''Define which revisions are going to be rebased and where
 
     repo: repo
     destmap: {srcrev: destrev}
     '''
     rebaseset = destmap.keys()
     originalwd = repo[b'.'].rev()
 
     # This check isn't strictly necessary, since mq detects commits over an
     # applied patch. But it prevents messing up the working directory when
     # a partially completed rebase is blocked by mq.
     if b'qtip' in repo.tags():
         mqapplied = set(repo[s.node].rev() for s in repo.mq.applied)
         if set(destmap.values()) & mqapplied:
             raise error.Abort(_(b'cannot rebase onto an applied mq patch'))
 
     # Get "cycle" error early by exhausting the generator.
     sortedsrc = list(sortsource(destmap))  # a list of sorted revs
     if not sortedsrc:
         raise error.Abort(_(b'no matching revisions'))
 
     # Only check the first batch of revisions to rebase not depending on other
     # rebaseset. This means "source is ancestor of destination" for the second
     # (and following) batches of revisions are not checked here. We rely on
     # "defineparents" to do that check.
     roots = list(repo.set(b'roots(%ld)', sortedsrc[0]))
     if not roots:
         raise error.Abort(_(b'no matching revisions'))
 
     def revof(r):
         return r.rev()
 
     roots = sorted(roots, key=revof)
     state = dict.fromkeys(rebaseset, revtodo)
     emptyrebase = len(sortedsrc) == 1
     for root in roots:
         dest = repo[destmap[root.rev()]]
         commonbase = root.ancestor(dest)
         if commonbase == root:
             raise error.Abort(_(b'source is ancestor of destination'))
         if commonbase == dest:
             wctx = repo[None]
             if dest == wctx.p1():
                 # when rebasing to '.', it will use the current wd branch name
                 samebranch = root.branch() == wctx.branch()
             else:
                 samebranch = root.branch() == dest.branch()
             if not collapse and samebranch and dest in root.parents():
                 # mark the revision as done by setting its new revision
                 # equal to its old (current) revisions
                 state[root.rev()] = root.rev()
                 repo.ui.debug(b'source is a child of destination\n')
                 continue
 
         emptyrebase = False
         repo.ui.debug(b'rebase onto %s starting from %s\n' % (dest, root))
     if emptyrebase:
         return None
     for rev in sorted(state):
         parents = [p for p in repo.changelog.parentrevs(rev) if p != nullrev]
         # if all parents of this revision are done, then so is this revision
         if parents and all((state.get(p) == p for p in parents)):
             state[rev] = rev
     return originalwd, destmap, state
 
 
 def clearrebased(
     ui,
     repo,
     destmap,
     state,
     skipped,
     collapsedas=None,
     keepf=False,
     fm=None,
     backup=True,
 ):
     """dispose of rebased revision at the end of the rebase
 
     If `collapsedas` is not None, the rebase was a collapse whose result if the
     `collapsedas` node.
 
     If `keepf` is not True, the rebase has --keep set and no nodes should be
     removed (but bookmarks still need to be moved).
 
     If `backup` is False, no backup will be stored when stripping rebased
     revisions.
     """
     tonode = repo.changelog.node
     replacements = {}
     moves = {}
     stripcleanup = not obsolete.isenabled(repo, obsolete.createmarkersopt)
 
     collapsednodes = []
     for rev, newrev in sorted(state.items()):
         if newrev >= 0 and newrev != rev:
             oldnode = tonode(rev)
             newnode = collapsedas or tonode(newrev)
             moves[oldnode] = newnode
             succs = None
             if rev in skipped:
                 if stripcleanup or not repo[rev].obsolete():
                     succs = ()
             elif collapsedas:
                 collapsednodes.append(oldnode)
             else:
                 succs = (newnode,)
             if succs is not None:
                 replacements[(oldnode,)] = succs
     if collapsednodes:
         replacements[tuple(collapsednodes)] = (collapsedas,)
     if fm:
         hf = fm.hexfunc
         fl = fm.formatlist
         fd = fm.formatdict
         changes = {}
         for oldns, newn in pycompat.iteritems(replacements):
             for oldn in oldns:
                 changes[hf(oldn)] = fl([hf(n) for n in newn], name=b'node')
         nodechanges = fd(changes, key=b"oldnode", value=b"newnodes")
         fm.data(nodechanges=nodechanges)
     if keepf:
         replacements = {}
     scmutil.cleanupnodes(repo, replacements, b'rebase', moves, backup=backup)
 
 
 def pullrebase(orig, ui, repo, *args, **opts):
     """Call rebase after pull if the latter has been invoked with --rebase"""
     if opts.get('rebase'):
         if ui.configbool(b'commands', b'rebase.requiredest'):
             msg = _(b'rebase destination required by configuration')
             hint = _(b'use hg pull followed by hg rebase -d DEST')
             raise error.Abort(msg, hint=hint)
 
         with repo.wlock(), repo.lock():
             if opts.get('update'):
                 del opts['update']
                 ui.debug(
                     b'--update and --rebase are not compatible, ignoring '
                     b'the update flag\n'
                 )
 
             cmdutil.checkunfinished(repo, skipmerge=True)
             cmdutil.bailifchanged(
                 repo,
                 hint=_(
                     b'cannot pull with rebase: '
                     b'please commit or shelve your changes first'
                 ),
             )
 
             revsprepull = len(repo)
             origpostincoming = commands.postincoming
 
             def _dummy(*args, **kwargs):
                 pass
 
             commands.postincoming = _dummy
             try:
                 ret = orig(ui, repo, *args, **opts)
             finally:
                 commands.postincoming = origpostincoming
             revspostpull = len(repo)
             if revspostpull > revsprepull:
                 # --rev option from pull conflict with rebase own --rev
                 # dropping it
                 if 'rev' in opts:
                     del opts['rev']
                 # positional argument from pull conflicts with rebase's own
                 # --source.
                 if 'source' in opts:
                     del opts['source']
                 # revsprepull is the len of the repo, not revnum of tip.
                 destspace = list(repo.changelog.revs(start=revsprepull))
                 opts['_destspace'] = destspace
                 try:
                     rebase(ui, repo, **opts)
                 except error.NoMergeDestAbort:
                     # we can maybe update instead
                     rev, _a, _b = destutil.destupdate(repo)
                     if rev == repo[b'.'].rev():
                         ui.status(_(b'nothing to rebase\n'))
                     else:
                         ui.status(_(b'nothing to rebase - updating instead\n'))
                         # not passing argument to get the bare update behavior
                         # with warning and trumpets
                         commands.update(ui, repo)
     else:
         if opts.get('tool'):
             raise error.Abort(_(b'--tool can only be used with --rebase'))
         ret = orig(ui, repo, *args, **opts)
 
     return ret
 
 
 def _filterobsoleterevs(repo, revs):
     """returns a set of the obsolete revisions in revs"""
     return set(r for r in revs if repo[r].obsolete())
 
 
 def _computeobsoletenotrebased(repo, rebaseobsrevs, destmap):
     """Return (obsoletenotrebased, obsoletewithoutsuccessorindestination).
 
     `obsoletenotrebased` is a mapping mapping obsolete => successor for all
     obsolete nodes to be rebased given in `rebaseobsrevs`.
 
     `obsoletewithoutsuccessorindestination` is a set with obsolete revisions
     without a successor in destination.
 
     `obsoleteextinctsuccessors` is a set of obsolete revisions with only
     obsolete successors.
     """
     obsoletenotrebased = {}
     obsoletewithoutsuccessorindestination = set()
     obsoleteextinctsuccessors = set()
 
     assert repo.filtername is None
     cl = repo.changelog
     get_rev = cl.index.get_rev
     extinctrevs = set(repo.revs(b'extinct()'))
     for srcrev in rebaseobsrevs:
         srcnode = cl.node(srcrev)
         # XXX: more advanced APIs are required to handle split correctly
         successors = set(obsutil.allsuccessors(repo.obsstore, [srcnode]))
         # obsutil.allsuccessors includes node itself
         successors.remove(srcnode)
         succrevs = {get_rev(s) for s in successors}
         succrevs.discard(None)
         if succrevs.issubset(extinctrevs):
             # all successors are extinct
             obsoleteextinctsuccessors.add(srcrev)
         if not successors:
             # no successor
             obsoletenotrebased[srcrev] = None
         else:
             dstrev = destmap[srcrev]
             for succrev in succrevs:
                 if cl.isancestorrev(succrev, dstrev):
                     obsoletenotrebased[srcrev] = succrev
                     break
             else:
                 # If 'srcrev' has a successor in rebase set but none in
                 # destination (which would be catched above), we shall skip it
                 # and its descendants to avoid divergence.
                 if srcrev in extinctrevs or any(s in destmap for s in succrevs):
                     obsoletewithoutsuccessorindestination.add(srcrev)
 
     return (
         obsoletenotrebased,
         obsoletewithoutsuccessorindestination,
         obsoleteextinctsuccessors,
     )
 
 
 def abortrebase(ui, repo):
     with repo.wlock(), repo.lock():
         rbsrt = rebaseruntime(repo, ui)
         rbsrt._prepareabortorcontinue(isabort=True)
 
 
 def continuerebase(ui, repo):
     with repo.wlock(), repo.lock():
         rbsrt = rebaseruntime(repo, ui)
         ms = mergemod.mergestate.read(repo)
         mergeutil.checkunresolved(ms)
         retcode = rbsrt._prepareabortorcontinue(isabort=False)
         if retcode is not None:
             return retcode
         rbsrt._performrebase(None)
         rbsrt._finishrebase()
 
 
 def summaryhook(ui, repo):
     if not repo.vfs.exists(b'rebasestate'):
         return
     try:
         rbsrt = rebaseruntime(repo, ui, {})
         rbsrt.restorestatus()
         state = rbsrt.state
     except error.RepoLookupError:
         # i18n: column positioning for "hg summary"
         msg = _(b'rebase: (use "hg rebase --abort" to clear broken state)\n')
         ui.write(msg)
         return
     numrebased = len([i for i in pycompat.itervalues(state) if i >= 0])
     # i18n: column positioning for "hg summary"
     ui.write(
         _(b'rebase: %s, %s (rebase --continue)\n')
         % (
             ui.label(_(b'%d rebased'), b'rebase.rebased') % numrebased,
             ui.label(_(b'%d remaining'), b'rebase.remaining')
             % (len(state) - numrebased),
         )
     )
 
 
 def uisetup(ui):
     # Replace pull with a decorator to provide --rebase option
     entry = extensions.wrapcommand(commands.table, b'pull', pullrebase)
     entry[1].append(
         (b'', b'rebase', None, _(b"rebase working directory to branch head"))
     )
     entry[1].append((b't', b'tool', b'', _(b"specify merge tool for rebase")))
     cmdutil.summaryhooks.add(b'rebase', summaryhook)
     statemod.addunfinished(
         b'rebase',
         fname=b'rebasestate',
         stopflag=True,
         continueflag=True,
         abortfunc=abortrebase,
         continuefunc=continuerebase,
     )