Port tools/clang-format/git-clang-format to work Python beyond 2.7

[abergmeier-dsfishlabs]

Summary

Since Python3 may deliberately not be available on Linux Systems (to prevent people from writing non-futureproof code), git-clang-format should not only work with Python2.7. This patch adds support for Python3.

[vsk]

tools/clang-format/git-clang-format

303

Why is this change needed (i.e: is there a functional difference between a list vs. a dict_keys here)?

[abergmeier-dsfishlabs]

Removed unnecessary list conversion.

[abergmeier-dsfishlabs]

Proper patch of last version (hopefully)

[vsk]

This lgtm. I haven't touched clang-format before, so it would be good to double-check with the code owner before committing.

[djasper]

Looks good.

[Eugene.Zelenko]

Looks like patch was not committed.

[shafik]

Should we close this?

tools/clang-format/git-clang-format

 For further details, run:                                                        
 git clang-format -h                                                              
                                                                                  
-Requires Python 2.7                                                              
+Requires a minimum of Python 2.7                                                 
 """               
 
+from __future__ import print_function
+
 import argparse
 import collections
 import contextlib

   if opts.verbose >= 1:
     ignored_files.difference_update(changed_lines)
     if ignored_files:
-      print 'Ignoring changes in the following files (wrong extension):'
+      print('Ignoring changes in the following files (wrong extension):')
       for filename in ignored_files:
-        print '   ', filename
+        print('   ', filename)
     if changed_lines:
-      print 'Running clang-format on the following files:'
+      print('Running clang-format on the following files:')
       for filename in changed_lines:
-        print '   ', filename
+        print('   ', filename)
   if not changed_lines:
-    print 'no modified files to format'
+    print('no modified files to format')
     return
   # The computed diff outputs absolute paths, so we must cd before accessing
   # those files.

                                                binary=opts.binary,
                                                style=opts.style)
   if opts.verbose >= 1:
-    print 'old tree:', old_tree
-    print 'new tree:', new_tree
+    print('old tree:', old_tree)
+    print('new tree:', new_tree)
   if old_tree == new_tree:
     if opts.verbose >= 0:
-      print 'clang-format did not modify any files'
+      print('clang-format did not modify any files')
   elif opts.diff:
     print_diff(old_tree, new_tree)
   else:
     changed_files = apply_changes(old_tree, new_tree, force=opts.force,
                                   patch_mode=opts.patch)
     if (opts.verbose >= 0 and not opts.patch) or opts.verbose >= 1:
-      print 'changed files:'
+      print('changed files:')
       for filename in changed_files:
-        print '   ', filename
+        print('   ', filename)
 
 
 def load_git_config(non_string_options=None):

 
   Returns the object ID (SHA-1) of the created tree."""
   def index_info_generator():
-    for filename, line_ranges in changed_lines.iteritems():
+    for filename, line_ranges in changed_lines.items():
       mode = oct(os.stat(filename).st_mode)
       blob_id = clang_format_to_blob(filename, line_ranges, binary=binary,
                                      style=style)

   if not force:
     unstaged_files = run('git', 'diff-files', '--name-status', *changed_files)
     if unstaged_files:
-      print >>sys.stderr, ('The following files would be modified but '
-                           'have unstaged changes:')
-      print >>sys.stderr, unstaged_files
-      print >>sys.stderr, 'Please commit, stage, or stash them first.'
+      print(('The following files would be modified but '
+                           'have unstaged changes:'), file=sys.stderr)
+      print(unstaged_files, file=sys.stderr)
+      print('Please commit, stage, or stash them first.', file=sys.stderr)
       sys.exit(2)
   if patch_mode:
     # In patch mode, we could just as well create an index from the new tree

   if p.returncode == 0:
     if stderr:
       if verbose:
-        print >>sys.stderr, '`%s` printed to stderr:' % ' '.join(args)
-      print >>sys.stderr, stderr.rstrip()
+        print('`%s` printed to stderr:' % ' '.join(args), file=sys.stderr)
+      print(stderr.rstrip(), file=sys.stderr)
     if strip:
       stdout = stdout.rstrip('\r\n')
     return stdout
   if verbose:
-    print >>sys.stderr, '`%s` returned %s' % (' '.join(args), p.returncode)
+    print('`%s` returned %s' % (' '.join(args), p.returncode), file=sys.stderr)
   if stderr:
-    print >>sys.stderr, stderr.rstrip()
+    print(stderr.rstrip(), file=sys.stderr)
   sys.exit(2)
 
 
 def die(message):
-  print >>sys.stderr, 'error:', message
+  print('error:', message, file=sys.stderr)
   sys.exit(2)