mercurial/destutil.py

rebase: choose default destination the same way as 'hg merge' (BC)

This changeset finally make 'hg rebase' choose its default destination using the
same logic as 'hg merge'. The previous default was "tipmost changeset on the
current branch", the new default is "the other head if there is only one".  This
change has multiple consequences:

- Multiple tests which were not rebasing anything (rebasing from tipmost head)
  are now rebasing on the other "lower" branch. This is the expected new
  behavior.

- A test is now explicitly aborting when there is too many heads on the branch.
  This is the expected behavior.

- We gained a better detection of the "nothing to rebase" case while performing
  'hg pull --rebase' so the message have been updated. Making clearer than an
  update was performed and why. This is beneficial side-effect.

- Rebasing from an active bookmark will behave the same as 'hg merge' from a
  bookmark.

# destutil.py - Mercurial utility function for command destination
#
#  Copyright Matt Mackall <[e-mail]> and other
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

from .i18n import _
from . import (
    bookmarks,
    error,
    obsolete,
)

def _destupdatevalidate(repo, rev, clean, check):
    """validate that the destination comply to various rules

    This exists as its own function to help wrapping from extensions."""
    wc = repo[None]
    p1 = wc.p1()
    if not clean:
        # Check that the update is linear.
        #
        # Mercurial do not allow update-merge for non linear pattern
        # (that would be technically possible but was considered too confusing
        # for user a long time ago)
        #
        # See mercurial.merge.update for details
        if p1.rev() not in repo.changelog.ancestors([rev], inclusive=True):
            dirty = wc.dirty(missing=True)
            foreground = obsolete.foreground(repo, [p1.node()])
            if not repo[rev].node() in foreground:
                if dirty:
                    msg = _("uncommitted changes")
                    hint = _("commit and merge, or update --clean to"
                             " discard changes")
                    raise error.UpdateAbort(msg, hint=hint)
                elif not check:  # destination is not a descendant.
                    msg = _("not a linear update")
                    hint = _("merge or update --check to force update")
                    raise error.UpdateAbort(msg, hint=hint)

def _destupdateobs(repo, clean, check):
    """decide of an update destination from obsolescence markers"""
    node = None
    wc = repo[None]
    p1 = wc.p1()
    movemark = None

    if p1.obsolete() and not p1.children():
        # allow updating to successors
        successors = obsolete.successorssets(repo, p1.node())

        # behavior of certain cases is as follows,
        #
        # divergent changesets: update to highest rev, similar to what
        #     is currently done when there are more than one head
        #     (i.e. 'tip')
        #
        # replaced changesets: same as divergent except we know there
        # is no conflict
        #
        # pruned changeset: no update is done; though, we could
        #     consider updating to the first non-obsolete parent,
        #     similar to what is current done for 'hg prune'

        if successors:
            # flatten the list here handles both divergent (len > 1)
            # and the usual case (len = 1)
            successors = [n for sub in successors for n in sub]

            # get the max revision for the given successors set,
            # i.e. the 'tip' of a set
            node = repo.revs('max(%ln)', successors).first()
            if bookmarks.isactivewdirparent(repo):
                movemark = repo['.'].node()
    return node, movemark, None

def _destupdatebook(repo, clean, check):
    """decide on an update destination from active bookmark"""
    # we also move the active bookmark, if any
    activemark = None
    node, movemark = bookmarks.calculateupdate(repo.ui, repo, None)
    if node is not None:
        activemark = node
    return node, movemark, activemark

def _destupdatebranch(repo, clean, check):
    """decide on an update destination from current branch"""
    wc = repo[None]
    movemark = node = None
    try:
        node = repo.revs('max(.::(head() and branch(%s)))'
                         , wc.branch()).first()
        if bookmarks.isactivewdirparent(repo):
            movemark = repo['.'].node()
    except error.RepoLookupError:
        if wc.branch() == 'default': # no default branch!
            node = repo.lookup('tip') # update to tip
        else:
            raise error.Abort(_("branch %s not found") % wc.branch())
    return node, movemark, None

# order in which each step should be evalutated
# steps are run until one finds a destination
destupdatesteps = ['evolution', 'bookmark', 'branch']
# mapping to ease extension overriding steps.
destupdatestepmap = {'evolution': _destupdateobs,
                     'bookmark': _destupdatebook,
                     'branch': _destupdatebranch,
                     }

def destupdate(repo, clean=False, check=False):
    """destination for bare update operation

    return (rev, movemark, activemark)

    - rev: the revision to update to,
    - movemark: node to move the active bookmark from
                (cf bookmark.calculate update),
    - activemark: a bookmark to activate at the end of the update.
    """
    node = movemark = activemark = None

    for step in destupdatesteps:
        node, movemark, activemark = destupdatestepmap[step](repo, clean, check)
        if node is not None:
            break
    rev = repo[node].rev()

    _destupdatevalidate(repo, rev, clean, check)

    return rev, movemark, activemark

msgdestmerge = {
    # too many matching divergent bookmark
    'toomanybookmarks':
        {'merge':
            (_("multiple matching bookmarks to merge -"
               " please merge with an explicit rev or bookmark"),
             _("run 'hg heads' to see all heads")),
         'rebase':
            (_("multiple matching bookmarks to rebase -"
               " please rebase to an explicit rev or bookmark"),
             _("run 'hg heads' to see all heads")),
        },
    # no other matching divergent bookmark
    'nootherbookmarks':
        {'merge':
            (_("no matching bookmark to merge - "
               "please merge with an explicit rev or bookmark"),
             _("run 'hg heads' to see all heads")),
         'rebase':
            (_("no matching bookmark to rebase - "
               "please rebase to an explicit rev or bookmark"),
             _("run 'hg heads' to see all heads")),
        },
    # branch have too many unbookmarked heads, no obvious destination
    'toomanyheads':
        {'merge':
            (_("branch '%s' has %d heads - please merge with an explicit rev"),
             _("run 'hg heads .' to see heads")),
         'rebase':
            (_("branch '%s' has %d heads - please rebase to an explicit rev"),
             _("run 'hg heads .' to see heads")),
        },
    # branch have no other unbookmarked heads
    'bookmarkedheads':
        {'merge':
            (_("heads are bookmarked - please merge with an explicit rev"),
             _("run 'hg heads' to see all heads")),
         'rebase':
            (_("heads are bookmarked - please rebase to an explicit rev"),
             _("run 'hg heads' to see all heads")),
        },
    # branch have just a single heads, but there is other branches
    'nootherbranchheads':
        {'merge':
            (_("branch '%s' has one head - please merge with an explicit rev"),
             _("run 'hg heads' to see all heads")),
         'rebase':
            (_("branch '%s' has one head - please rebase to an explicit rev"),
             _("run 'hg heads' to see all heads")),
        },
    # repository have a single head
    'nootherheads':
        {'merge':
            (_('nothing to merge'),
            None),
         'rebase':
            (_('nothing to rebase'),
            None),
        },
    # repository have a single head and we are not on it
    'nootherheadsbehind':
        {'merge':
            (_('nothing to merge'),
             _("use 'hg update' instead")),
         'rebase':
            (_('nothing to rebase'),
             _("use 'hg update' instead")),
        },
    # We are not on a head
    'notatheads':
        {'merge':
            (_('working directory not at a head revision'),
             _("use 'hg update' or merge with an explicit revision")),
         'rebase':
            (_('working directory not at a head revision'),
             _("use 'hg update' or rebase to an explicit revision"))
        },
    'emptysourceset':
        {'merge':
            (_('source set is empty'),
             None),
         'rebase':
            (_('source set is empty'),
             None),
        },
    'multiplebranchessourceset':
        {'merge':
            (_('source set is rooted in multiple branches'),
             None),
         'rebase':
            (_('rebaseset is rooted in multiple named branches'),
             _('specify an explicit destination with --dest')),
        },
    }

def _destmergebook(repo, action='merge', sourceset=None):
    """find merge destination in the active bookmark case"""
    node = None
    bmheads = repo.bookmarkheads(repo._activebookmark)
    curhead = repo[repo._activebookmark].node()
    if len(bmheads) == 2:
        if curhead == bmheads[0]:
            node = bmheads[1]
        else:
            node = bmheads[0]
    elif len(bmheads) > 2:
        msg, hint = msgdestmerge['toomanybookmarks'][action]
        raise error.ManyMergeDestAbort(msg, hint=hint)
    elif len(bmheads) <= 1:
        msg, hint = msgdestmerge['nootherbookmarks'][action]
        raise error.NoMergeDestAbort(msg, hint=hint)
    assert node is not None
    return node

def _destmergebranch(repo, action='merge', sourceset=None, onheadcheck=True):
    """find merge destination based on branch heads"""
    node = None

    if sourceset is None:
        sourceset = [repo[repo.dirstate.p1()].rev()]
        branch = repo.dirstate.branch()
    elif not sourceset:
        msg, hint = msgdestmerge['emptysourceset'][action]
        raise error.NoMergeDestAbort(msg, hint=hint)
    else:
        branch = None
        for ctx in repo.set('roots(%ld::%ld)', sourceset, sourceset):
            if branch is not None and ctx.branch() != branch:
                msg, hint = msgdestmerge['multiplebranchessourceset'][action]
                raise error.ManyMergeDestAbort(msg, hint=hint)
            branch = ctx.branch()

    bheads = repo.branchheads(branch)
    onhead = repo.revs('%ld and %ln', sourceset, bheads)
    if onheadcheck and not onhead:
        # Case A: working copy if not on a head. (merge only)
        #
        # This is probably a user mistake We bailout pointing at 'hg update'
        if len(repo.heads()) <= 1:
            msg, hint = msgdestmerge['nootherheadsbehind'][action]
        else:
            msg, hint = msgdestmerge['notatheads'][action]
        raise error.Abort(msg, hint=hint)
    # remove heads descendants of source from the set
    bheads = list(repo.revs('%ln - (%ld::)', bheads, sourceset))
    # filters out bookmarked heads
    nbhs = list(repo.revs('%ld - bookmark()', bheads))
    if len(nbhs) > 1:
        # Case B: There is more than 1 other anonymous heads
        #
        # This means that there will be more than 1 candidate. This is
        # ambiguous. We abort asking the user to pick as explicit destination
        # instead.
        msg, hint = msgdestmerge['toomanyheads'][action]
        msg %= (branch, len(bheads) + 1)
        raise error.ManyMergeDestAbort(msg, hint=hint)
    elif not nbhs:
        # Case B: There is no other anonymous heads
        #
        # This means that there is no natural candidate to merge with.
        # We abort, with various messages for various cases.
        if bheads:
            msg, hint = msgdestmerge['bookmarkedheads'][action]
        elif len(repo.heads()) > 1:
            msg, hint = msgdestmerge['nootherbranchheads'][action]
            msg %= branch
        elif not onhead:
            # if 'onheadcheck == False' (rebase case),
            # this was not caught in Case A.
            msg, hint = msgdestmerge['nootherheadsbehind'][action]
        else:
            msg, hint = msgdestmerge['nootherheads'][action]
        raise error.NoMergeDestAbort(msg, hint=hint)
    else:
        node = nbhs[0]
    assert node is not None
    return node

def destmerge(repo, action='merge', sourceset=None, onheadcheck=True):
    """return the default destination for a merge

    (or raise exception about why it can't pick one)

    :action: the action being performed, controls emitted error message
    """
    if repo._activebookmark:
        node = _destmergebook(repo, action=action, sourceset=sourceset)
    else:
        node = _destmergebranch(repo, action=action, sourceset=sourceset,
                                onheadcheck=onheadcheck)
    return repo[node].rev()

histeditdefaultrevset = 'reverse(only(.) and not public() and not ::merge())'

def desthistedit(ui, repo):
    """Default base revision to edit for `hg histedit`."""
    # Avoid cycle: scmutil -> revset -> destutil
    from . import scmutil

    default = ui.config('histedit', 'defaultrev', histeditdefaultrevset)
    if default:
        revs = scmutil.revrange(repo, [default])
        if revs:
            # The revset supplied by the user may not be in ascending order nor
            # take the first revision. So do this manually.
            revs.sort()
            return revs.first()

    return None

def _statusotherbook(ui, repo):
    bmheads = repo.bookmarkheads(repo._activebookmark)
    curhead = repo[repo._activebookmark].node()
    if repo.revs('%n and parents()', curhead):
        # we are on the active bookmark
        bmheads = [b for b in bmheads if curhead != b]
        if bmheads:
            msg = _('%i other divergent bookmarks for "%s"\n')
            ui.status(msg % (len(bmheads), repo._activebookmark))

def _statusotherbranchheads(ui, repo):
    currentbranch = repo.dirstate.branch()
    heads = repo.branchheads(currentbranch)
    l = len(heads)
    if repo.revs('%ln and parents()', heads):
        # we are on a head
        heads = repo.revs('%ln - parents()', heads)
        if heads and l != len(heads):
            ui.status(_('%i other heads for branch "%s"\n') %
                      (len(heads), currentbranch))

def statusotherdests(ui, repo):
    """Print message about other head"""
    # XXX we should probably include a hint:
    # - about what to do
    # - how to see such heads
    if repo._activebookmark:
        _statusotherbook(ui, repo)
    else:
        _statusotherbranchheads(ui, repo)