view hgext/hooklib/reject_merge_commits.py @ 51901:f4733654f144

typing: add `from __future__ import annotations` to most files

Now that py36 is no longer supported, we can postpone annotation evaluation.
This means that the quoting is usually optional (for things imported under the
guard of `if typing.TYPE_CHECKING:` to avoid circular imports), and there's less
overhead on startup[1].

There may be some missing here.  I backed out 6000f5b25c9b (which removed the
`from __future__ import ...` that was supporting py2), reverted the changes in
`contrib/`, `doc/`, and `tests/`, and then ran:

    $ hg status -n --change . | \
        xargs sed -i -e 's/from __future__ import .*$/from __future__ import annotations/'

There were some minor tweaks needed when reviewing (mostly making the spacing
around the import consistent, and `mercurial/testing/__init__.py` had a
multiline import that wasn't fully rewritten.

[1] https://docs.python.org/3/whatsnew/3.7.html#pep-563-postponed-evaluation-of-annotations

# Copyright 2020 Joerg Sonnenberger <[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.

"""reject_merge_commits is a hook to check new changesets for merge commits.
Merge commits are allowed only between different branches, i.e. merging
a feature branch into the main development branch. This can be used to
enforce policies for linear commit histories.

Usage:
  [hooks]
  pretxnchangegroup.reject_merge_commits = \
    python:hgext.hooklib.reject_merge_commits.hook
"""

from __future__ import annotations

from mercurial.i18n import _
from mercurial import (
    error,
    pycompat,
)


def hook(ui, repo, hooktype, node=None, **kwargs):
    if hooktype != b"pretxnchangegroup":
        raise error.Abort(
            _(b'Unsupported hook type %r') % pycompat.bytestr(hooktype)
        )

    ctx = repo.unfiltered()[node]
    for rev in repo.changelog.revs(start=ctx.rev()):
        rev = repo[rev]
        parents = rev.parents()
        if len(parents) < 2:
            continue
        if all(repo[p].branch() == rev.branch() for p in parents):
            raise error.Abort(
                _(
                    b'%s rejected as merge on the same branch. '
                    b'Please consider rebase.'
                )
                % rev
            )