view mercurial/rewriteutil.py @ 39899:f9232b0310ef

pullreport: issue a message about "extinct" pulled changesets

Changeset pulled from a remote repository while already obsolete locally can
end up hidden after the pull. Hiding obsolete changesets is a good behavior
but silently "skipping" some of the pulled content can get confusing.

We now detect this situation and emit a message about it. The message is
simple and the wording could be improved, however, we focus on the detection
here. Evolution is still an experimental feature, so the output is open to
changes.

In particular, we could point out at the latest successors of the obsolete
changesets, however, it can get tricky is there are many of them. So we delay
these improvements to another adventure.

Another easy improvement would be to merge this message with the previous line
about the new nodes and their phases.

This is a good example of cases where we can only transmit a limited amount of
data to users by default. We need some sort of "transaction journal" we could
point the user to.

# rewriteutil.py - utility functions for rewriting changesets
#
# Copyright 2017 Octobus <[e-mail]>
#
# 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 (
    error,
    node,
    obsolete,
    revset,
)

def precheck(repo, revs, action='rewrite'):
    """check if revs can be rewritten
    action is used to control the error message.

    Make sure this function is called after taking the lock.
    """
    if node.nullrev in revs:
        msg = _("cannot %s null changeset") % (action)
        hint = _("no changeset checked out")
        raise error.Abort(msg, hint=hint)

    publicrevs = repo.revs('%ld and public()', revs)
    if len(repo[None].parents()) > 1:
        raise error.Abort(_("cannot %s while merging") % action)

    if publicrevs:
        msg = _("cannot %s public changesets") % (action)
        hint = _("see 'hg help phases' for details")
        raise error.Abort(msg, hint=hint)

    newunstable = disallowednewunstable(repo, revs)
    if newunstable:
        raise error.Abort(_("cannot %s changeset with children") % action)

def disallowednewunstable(repo, revs):
    """Checks whether editing the revs will create new unstable changesets and
    are we allowed to create them.

    To allow new unstable changesets, set the config:
        `experimental.evolution.allowunstable=True`
    """
    allowunstable = obsolete.isenabled(repo, obsolete.allowunstableopt)
    if allowunstable:
        return revset.baseset()
    return repo.revs("(%ld::) - %ld", revs, revs)