[clang-tidy] Fix performance-noexcept-move-constructor-fix.cpp on non-English locale

[aganea]

Summary

When running on Windows under the following locale:

D:\llvm-project>python
Python 3.8.0 (tags/v3.8.0:fa919fd, Oct 14 2019, 19:37:50) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import locale
>>> locale.getlocale()
('French_Canada', '1252')

This patch fixes the following issue:

# command stderr:
Traceback (most recent call last):
  File "D:/llvm-project/clang-tools-extra/test/../test\clang-tidy\check_clang_tidy.py", line 249, in <module>
    main()
  File "D:/llvm-project/clang-tools-extra/test/../test\clang-tidy\check_clang_tidy.py", line 245, in main
    run_test_once(args, extra_args)
  File "D:/llvm-project/clang-tools-extra/test/../test\clang-tidy\check_clang_tidy.py", line 162, in run_test_once
    diff_output.decode() +
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe0 in position 2050: invalid continuation byte

This is caused by diff reporting no EOL on the last line, and unfortunately this is written in French with accentuation on my locale.

[aganea]

Better fix.

[rnk]

lgtm, if the diff comes out wrong, that will not result in an incorrect pass/fail, but only less debugable output.

clang-tools-extra/test/clang-tidy/check_clang_tidy.py

def run_test_once(args, extra_args):
   try:
     diff_output = subprocess.check_output(
         ['diff', '-u', original_file_name, temp_file_name],
         stderr=subprocess.STDOUT)
   except subprocess.CalledProcessError as e:
     diff_output = e.output
 
   print('------------------------------ Fixes -----------------------------\n' +
-        diff_output.decode() +
+        diff_output.decode(errors='ignore') +
         '\n------------------------------------------------------------------')
 
   if has_check_fixes:
     try:
       subprocess.check_output(
           ['FileCheck', '-input-file=' + temp_file_name, input_file_name,
            '-check-prefixes=' + ','.join(check_fixes_prefixes),
            '-strict-whitespace'],