contrib/check-py3-compat.py

tests: omit -p for external diff via extdiff extension for portability

Before this patch, some tests using external "diff" command via
extdiff extension fail on Solaris, because "-p" (show which C function
each change is in) option isn't supported by system standard "diff" on
Solaris, even though extdiff passes it to external "diff" by default.

Fortunately, this non-portable option isn't important for (current, at
least) tests using external "diff" command via extdiff extension.

This patch omits "-p" for external "diff" command via extdiff
extension for portability of tests, and adds check-code.py a rule to
detect invocation of "diff" with "-p".

Newly added check-code.py rule examines only lines generated by
external "diff" with "-r", because strict examination might
misidentify "hg diff -p" or other complicated lines consisting of
"diff" string as wrong one.

This patch is a part of making tests using external "diff" portable,
and tests below aren't yet portable even after this patch.

  test-graft.t
  test-largefiles-update.t
  test-subrepo-deep-nested-change.t

#!/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()

    # Ignore empty files.
    if not content.strip():
        return

    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)