contrib/check-py3-compat.py

mdiff: tweak calls into `bdiff.fixws` to match its type hints

It turns out that protocol classes can be used for modules too, which is great
because all of the dynamically loaded modules (and their attributes) are
currently inferred as `Any`.  See the next commit for details.

A protocol class for the `bdiff` module detected this (trivial) mismatch, so
correct it first.  The various implementations of this method are typed as
taking a `bool`.  The `cext` implementation parses its arguments with
`PyArg_ParseTuple(args, "Sb:fixws", &s, &allws)`, which wants an `int`.  But
experimenting in `hg debugshell` under py38, passing `True` or `False` to
`cext.fixws()` also works.  We can change the implementation to use "p" (which
was introduced in py33) instead of "b", but that's beyond the scope of this.

#!/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)