clang-tidy: Add `-use-color` for `run-clang-tidy.py` in order to make it sane with `clang-tidy` coloring argument

[Abpostelnicu]

Summary

Afer this commit landed we always have coloured diagnotic messages. Maybe it's a good idea to have the same default behaviour as clang-tidy has.

[njames93]

Would it be wise to use os.isatty(sys.stdout.fileno()) as the value if left unspecified.
As we capture stdout from clang-tidy, clang-tidy assumes we aren't connected to a terminal and thus disables colours, unless explicitly enabled.
Therefore if our python script is known to be running from a terminal and we haven't specified to use colours. We should enable --use-color.

Based off this, I think the argument should be a carbon copy of the --use-color option from clang-tidy.

[Abpostelnicu]

Add -use-color argument to make it sane with clang-tidy --use-color argument.

[simon.giesecke]

I think this would be a useful change. In the current state, one needs to modify the script to run this in a context where coloring is not supported.

clang-tools-extra/clang-tidy/tool/run-clang-tidy.py

 
 def make_absolute(f, directory):
   if os.path.isabs(f):
     return f
   return os.path.normpath(os.path.join(directory, f))
 
 
 def get_tidy_invocation(f, clang_tidy_binary, checks, tmpdir, build_path,
-                        header_filter, allow_enabling_alpha_checkers,
-                        extra_arg, extra_arg_before, quiet, config):
+                        header_filter, use_color,
+                        allow_enabling_alpha_checkers, extra_arg,
+                        extra_arg_before, quiet, config):
   """Gets a command line for clang-tidy."""
-  start = [clang_tidy_binary, '--use-color']
+  start = [clang_tidy_binary]
+  # Only if we are connected to a tty we can check for enabling color mode
+  if os.isatty(sys.stdout.fileno()) and use_color:
+    start.append('--use-color')
   if allow_enabling_alpha_checkers:
     start.append('-allow-enabling-analyzer-alpha-checkers')
   if header_filter is not None:
     start.append('-header-filter=' + header_filter)
   if checks:
     start.append('-checks=' + checks)
   if tmpdir is not None:
     start.append('-export-fixes')

 
 
 def run_tidy(args, tmpdir, build_path, queue, lock, failed_files):
   """Takes filenames out of queue and runs clang-tidy on them."""
   while True:
     name = queue.get()
     invocation = get_tidy_invocation(name, args.clang_tidy_binary, args.checks,
                                      tmpdir, build_path, args.header_filter,
+                                     args.use_color,
                                      args.allow_enabling_alpha_checkers,
                                      args.extra_arg, args.extra_arg_before,
                                      args.quiet, args.config)
 
     proc = subprocess.Popen(invocation, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
     output, err = proc.communicate()
     if proc.returncode != 0:
       failed_files.append(name)
def main():
   parser.add_argument('-config', default=None,
                       help='Specifies a configuration in YAML/JSON format: '
                       '  -config="{Checks: \'*\', '
                       '                       CheckOptions: [{key: x, '
                       '                                       value: y}]}" '
                       'When the value is empty, clang-tidy will '
                       'attempt to find a file named .clang-tidy for '
                       'each source file in its parent directories.')
+  parser.add_argument('-use-color', action='store_true',
+                      help='Enables diagnostic message colors.')
   parser.add_argument('-header-filter', default=None,
                       help='regular expression matching the names of the '
                       'headers to output diagnostics from. Diagnostics from '
                       'the main file of each translation unit are always '
                       'displayed.')
   if yaml:
     parser.add_argument('-export-fixes', metavar='filename', dest='export_fixes',
                         help='Create a yaml file to store suggested fixes in, '