clang-format-diff: Make it work with python3 too

[MarcoFalke]

Summary

It is not necessary, but would be nice if the script run on python3 as well (as opposed to only python2, which is going to be deprecated https://pythonclock.org/)

[MarcoFalke]

In python2.7:
TypeError: 'encoding' is an invalid keyword argument for this function

So remove it for now.

[krasimir]

Sorry, I'm not familiar with this tool. Could you elaborate:

• why is this switch necessary?
• what's expected to be supported with it?
• how do I test it?

[MarcoFalke]

why is this switch necessary?

It is not necessary, but would be nice if the script run on python3 as well (as opposed to only python2, which is going to be deprecated https://pythonclock.org/)

what's expected to be supported with it?

I'd assume python2.7 (which is the only supported python2) and everything from python3.4 and upward.

how do I test it?

The clang-format-diff.py is a wrapper around clang-format, to format only a diff. You can get any diff, e.g. the last ten commits to the master branch:

git diff HEAD~10 -U0 | python2 ./tools/clang-format/clang-format-diff.py

(You might have to pass -p1)

Then test that the following options work with both python2 and python3:

-i -v  # flags
-regex # could be -regex '.*\.h'
-iregex # could be -iregex '.*\.H'

[lebedev.ri]

Please always upload all patches with the full context (-U99999)

tools/clang-format/clang-format-diff.py

1

Why do you need to *switch* the default?
What's wrong with [at least starting with] just making sure it works with both python 2 and 3?

[krasimir]

tools/clang-format/clang-format-diff.py

1

+1: I'm not an expert, but IMO python2.7 is more prevalent.

[MarcoFalke]

Keep python2 by default for now

[krasimir]

Checked with both python 2 and python 3 as suggested. Works like a charm! Thank you!

[krasimir]

MarcoFalke: do you need someone to submit this for you?

[MarcoFalke]

In D48098#1174771, @krasimir wrote:

MarcoFalke: do you need someone to submit this for you?

Yes, I'd appreciate any help on how to submit this for merge.

tools/clang-format/clang-format-diff.py

-#!/usr/bin/env python
+#!/usr/bin/env python3
 #
 #===- clang-format-diff.py - ClangFormat Diff Reformatter ----*- python -*--===#
 #

 import argparse
 import difflib
 import re
-import string
 import subprocess
-import StringIO
 import sys
+try:
+  from StringIO import StringIO
+except ImportError:
+   from io import StringIO
 
 
 def main():

         line_count = int(match.group(3))
       if line_count == 0:
         continue
-      end_line = start_line + line_count - 1;
+      end_line = start_line + line_count - 1
       lines_by_file.setdefault(filename, []).extend(
           ['-lines', str(start_line) + ':' + str(end_line)])
 
   # Reformat files containing changes in place.
-  for filename, lines in lines_by_file.iteritems():
+  for filename, lines in lines_by_file.items():
     if args.i and args.verbose:
-      print 'Formatting', filename
+      print('Formatting {}'.format(filename))
     command = [args.binary, filename]
     if args.i:
       command.append('-i')

     command.extend(lines)
     if args.style:
       command.extend(['-style', args.style])
-    p = subprocess.Popen(command, stdout=subprocess.PIPE,
-                         stderr=None, stdin=subprocess.PIPE)
+    p = subprocess.Popen(command,
+                         stdout=subprocess.PIPE,
+                         stderr=None,
+                         stdin=subprocess.PIPE,
+                         universal_newlines=True)
     stdout, stderr = p.communicate()
     if p.returncode != 0:
-      sys.exit(p.returncode);
+      sys.exit(p.returncode)
 
     if not args.i:
       with open(filename) as f:
         code = f.readlines()
-      formatted_code = StringIO.StringIO(stdout).readlines()
+      formatted_code = StringIO(stdout).readlines()
       diff = difflib.unified_diff(code, formatted_code,
                                   filename, filename,
                                   '(before formatting)', '(after formatting)')
-      diff_string = string.join(diff, '')
+      diff_string = ''.join(diff)
       if len(diff_string) > 0:
         sys.stdout.write(diff_string)