contrib/check-py3-compat.py

localrepo: pass root manifest into manifestlog.__init__

Today, localrepository has a method that can be overloaded which
returns an instance of the root manifest storage object. When a
manifestlog is created, it calls this private method and stores
the root manifest object on it.

This "hook" on localrepository isn't part of the documented interface.
It isn't compatible with our desire to make repo storage determined
before the repo object is constructed.

This commit changes manifestlog.__init__ to accept the root
storage object instead of calling into the repo to construct it.
By doing things this way, the repo instance is responsible for
constructing the manifest storage object directly.

This does mean that other derived repo types need to overload
manifestlog(). But they should have been doing this already,
as manifestlog() is typically decorated in a storage-specific way.
e.g. localrepository.manifestlog() is decorated as
@storecache('00manifest.i'). And this assumes that a 00manifest.i
file exists in the store vfs. This condition may not hold for
repository types using non-revlog storage. So it is important
for special repo types to override manifestlog() to remove this
file association.

The code changed in perf is wrong because it isn't compatible with
older Mercurial versions. But I'm pretty sure the code was broken
on older versions before this commit. It only affects `hg perftags`.
I don't care enough to fix that at this time.

.. api::

   ``manifest.manifestlog.__init__()`` now receives the root manifest
   storage instance instead of calling into a private method on
   the repo object to obtain it.

Differential Revision: https://phab.mercurial-scm.org/D4641

#!/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 importlib
import os
import sys
import traceback

def check_compat_py2(f):
    """Check Python 3 compatibility for a file with Python 2"""
    with open(f, 'rb') as fh:
        content = fh.read()
    root = ast.parse(content)

    # Ignore empty files.
    if not root.body:
        return

    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)

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)
    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__':
    if sys.version_info[0] == 2:
        fn = check_compat_py2
    else:
        fn = check_compat_py3

    for f in sys.argv[1:]:
        fn(f)

    sys.exit(0)