view mercurial/rewriteutil.py @ 35830:fb39f6a8a864 stable

setup: only allow Python 3 from a source checkout (issue5804)

People are running `pip install Mercurial` with Python 3 and that
is working because not everything performs a Python version
compatibility check.

Modern versions of pip do recognize the "python_requires" keyword
(https://packaging.python.org/tutorials/distributing-packages/#python-requires)
which we set if using setuptools. But this isn't set nor recognized
everywhere.

To prevent people from accidentally installing Mercurial with Python
3 until Python 3 is officially supported, have setup.py fail when
run with Python 3. But don't fail if we're running from a source
checkout, as we don't want to anger Mercurial developers hacking
on Python 3 nor Mercurial's test automation running from source
checkouts. People running setup.py from source checkouts could still
fall through a Python 3 crack. But at least the
`pip install Mercurial` attempt will get nipped in the bud.

# 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)