contrib/check-py3-compat.py

rebase: add boolean config item rebase.store-source

This allows to use rebase without recording a rebase_source extra
field. This is useful for example to build a mirror converted from
another SCM (such as svn) by converting only new revisions, and
then incrementally add them to the destination by pulling from the
newly converted (unrelated) repo and rebasing the new revisions
onto the last old already stored changeset. Without this patch the
rebased changesets would always receive some rebase_source that
would depend on the particular history of the conversion process,
instead of only depending on the original source revisions.

This is used to implement a hg mirror repo of SvarDOS (a partially
nonfree but completely redistributable DOS distribution) in the
scripts at https://hg.pushbx.org/ecm/svardos.scr/

In particular, cre.sh creates an svn mirror, upd.sh recreates an
entire hg repo from the svn mirror (which takes too long to do in a
regular job), and akt.sh uses hg convert with the config item
convert.svn.startrev to incrementally convert only the two most
recent revisions already found in the mirror destination plus any
possible new revisions. If any are found, the temporary repo's
changesets are pulled into the destination (as changesets from an
unrelated repository). Then the changesets corresponding to the new
revisions are rebased onto the prior final changeset. (Finally, the
two remaining duplicates of the prior head and its parent are
stripped from the destination repository.)

Without this patch, the particular rebase_source extra field would
depend on the order and times at which akt.sh was used, instead of
only depending on the source repository. In other words, whatever
sequence of upd.sh and akt.sh is used at whatever times, it is
desired that the final output repositories always match each other
exactly.

#!/usr/bin/env python3
#
# 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.


import ast
import importlib
import os
import sys
import traceback
import warnings


def check_compat_py3(f):
    """Check Python 3 compatibility of a file with Python 3."""
    with open(f, 'rb') as fh:
        content = fh.read()

    try:
        ast.parse(content, filename=f)
    except SyntaxError as e:
        print('%s: invalid syntax: %s' % (f, e))
        return

    # Try to import the module.
    # For now we only support modules in packages because figuring out module
    # paths for things not in a package can be confusing.
    if f.startswith(
        ('hgdemandimport/', 'hgext/', 'mercurial/')
    ) and not f.endswith('__init__.py'):
        assert f.endswith('.py')
        name = f.replace('/', '.')[:-3]
        try:
            importlib.import_module(name)
        except Exception as e:
            exc_type, exc_value, tb = sys.exc_info()
            # We walk the stack and ignore frames from our custom importer,
            # import mechanisms, and stdlib modules. This kinda/sorta
            # emulates CPython behavior in import.c while also attempting
            # to pin blame on a Mercurial file.
            for frame in reversed(traceback.extract_tb(tb)):
                if frame.name == '_call_with_frames_removed':
                    continue
                if 'importlib' in frame.filename:
                    continue
                if 'mercurial/__init__.py' in frame.filename:
                    continue
                if frame.filename.startswith(sys.prefix):
                    continue
                break

            if frame.filename:
                filename = os.path.basename(frame.filename)
                print(
                    '%s: error importing: <%s> %s (error at %s:%d)'
                    % (f, type(e).__name__, e, filename, frame.lineno)
                )
            else:
                print(
                    '%s: error importing module: <%s> %s (line %d)'
                    % (f, type(e).__name__, e, frame.lineno)
                )


if __name__ == '__main__':
    # check_compat_py3 will import every filename we specify as long as it
    # starts with one of a few prefixes. It does this by converting
    # specified filenames like 'mercurial/foo.py' to 'mercurial.foo' and
    # importing that. When running standalone (not as part of a test), this
    # means we actually import the installed versions, not the files we just
    # specified. When running as test-check-py3-compat.t, we technically
    # would import the correct paths, but it's cleaner to have both cases
    # use the same import logic.
    sys.path.insert(0, os.getcwd())

    for f in sys.argv[1:]:
        with warnings.catch_warnings(record=True) as warns:
            check_compat_py3(f)

        for w in warns:
            print(
                warnings.formatwarning(
                    w.message, w.category, w.filename, w.lineno
                ).rstrip()
            )

    sys.exit(0)