contrib/check-py3-compat.py

discovery: properly filter changeset in 'peer.known' (issue4982)

The 'peer.known' call (handled at the repository level) was applying its own
manual filtering (looking at phases) instead of relying on the repoview
mechanism. This led to the discovery finding more "common" node that
'getbundle' was willing to recognised. From there, bad things happen, issue4982
is a symptom of it. While situations like described in issue4982 can still
happen because of race conditions, fixing 'peer.known' is important for
consistency in all cases.

We update the code to use 'repoview' filtering. This lead to small changes in
the tests for exchanging obsolescence marker because the discovery yields
different results.

The test affected in 'test-obsolete-changeset-exchange.t' is a test for
issue4982 getting back to its expected state.

#!/usr/bin/env python
#
# check-py3-compat - check Python 3 compatibility of Mercurial files
#
# Copyright 2015 Gregory Szorc <[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, print_function

import ast
import sys

def check_compat(f):
    """Check Python 3 compatibility for a file."""
    with open(f, 'rb') as fh:
        content = fh.read()

    root = ast.parse(content)
    futures = set()
    haveprint = False
    for node in ast.walk(root):
        if isinstance(node, ast.ImportFrom):
            if node.module == '__future__':
                futures |= set(n.name for n in node.names)
        elif isinstance(node, ast.Print):
            haveprint = True

    if 'absolute_import' not in futures:
        print('%s not using absolute_import' % f)
    if haveprint and 'print_function' not in futures:
        print('%s requires print_function' % f)

if __name__ == '__main__':
    for f in sys.argv[1:]:
        check_compat(f)

    sys.exit(0)