check-py3-compat: use an absolute path in sys.path

The idea and rationale is similar to https://phab.mercurial-scm.org/D12599
(landed as 1b6e381521c5).

Differential Revision: https://phab.mercurial-scm.org/D12621

contrib/check-py3-compat.py

@@ -1,122 +1,122 b''
 #!/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.
 
 from __future__ import absolute_import, print_function
 
 import ast
 import importlib
 import os
 import sys
 import traceback
 import warnings
 
 
 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 |= {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, 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__':
     if sys.version_info[0] == 2:
         fn = check_compat_py2
     else:
         # 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, '.')
+        sys.path.insert(0, os.getcwd())
         fn = check_compat_py3
 
     for f in sys.argv[1:]:
         with warnings.catch_warnings(record=True) as warns:
             fn(f)
 
         for w in warns:
             print(
                 warnings.formatwarning(
                     w.message, w.category, w.filename, w.lineno
                 ).rstrip()
             )
 
     sys.exit(0)