[clang-format] update string comparison in clang-format.py

[pseyfert]

Summary

Python 3.8 introduces a SyntaxWarning about string comparisons with 'is'. This commit updates the string comparison in clang-format.py that is done with 'is not' to '!='. This should not break compatibility with older python versions (tested 3.4.9, 2.7.17, 2.7.5, 3.8.0).

[klimek]

lg

[pseyfert]

PS: I do not have commit access, so someone with the rights would need to land this for me. Thanks in advance.

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

else:
     lines = stdout.decode(encoding).split('\n')
     output = json.loads(lines[0])
     # Strip off the trailing newline (added above).
     # This maintains trailing empty lines present in the buffer if
     # the -lines specification requests them to remain unchanged.
     lines = lines[1:-1]
     sequence = difflib.SequenceMatcher(None, buf, lines)
     for op in reversed(sequence.get_opcodes()):
-      if op[0] is not 'equal':
+      if op[0] != 'equal':
         vim.current.buffer[op[1]:op[2]] = lines[op[3]:op[4]]
     if output.get('IncompleteFormat'):
       print('clang-format: incomplete (syntax errors)')
     vim.command('goto %d' % (output['Cursor'] + 1))
 
 main()