[clang-tidy] Add test support for the fix description.

[hokein]

Summary

Add a new annotation "CHECK-FIX-DESCRIPTIONS" to lit test to
verify the fix description provided by checks.

[hokein]

cleanup

[alexfh]

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

109

Wait, how do "check descriptions" differ from notes?

[hokein]

Use CHECK-NOTES.

[hokein]

Based on our last offline discussion, it is possible to use CHECK-NOTES to verify fix descriptions. However, CHECK-NOTES enforce sto verify all note diagnostic messages, some existing tests will be failed because they don't cover all notes (the number is not large, only ~60), I'll update the tests when updating the relative checks.

Finally (after every check provides fix descriptions), we may deprecate CHECK-MESSAGES, and in favor of CHECK-NOTES.

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

if resource_dir is not None:
     clang_tidy_extra_args.append('-resource-dir=%s' % resource_dir)
 
   with open(input_file_name, 'r') as input_file:
     input_text = input_file.read()
 
   check_fixes_prefixes = []
   check_messages_prefixes = []
   check_notes_prefixes = []
+  check_fix_descriptions_prefixes = []
 
   has_check_fixes = False
   has_check_messages = False
   has_check_notes = False
+  has_check_fix_descriptions = False
 
   for check in args.check_suffix:
     if check and not re.match('^[A-Z0-9\-]+$', check):
       sys.exit('Only A..Z, 0..9 and "-" are ' +
         'allowed in check suffixes list, but "%s" was given' % (check))
 
     file_check_suffix = ('-' + check) if check else ''
     check_fixes_prefix = 'CHECK-FIXES' + file_check_suffix
     check_messages_prefix = 'CHECK-MESSAGES' + file_check_suffix
     check_notes_prefix = 'CHECK-NOTES' + file_check_suffix
+    check_fix_descriptions_prefix = 'CHECK-FIX-DESCRIPTIONS' + file_check_suffix
 
     has_check_fix = check_fixes_prefix in input_text
     has_check_message = check_messages_prefix in input_text
     has_check_note = check_notes_prefix in input_text
+    has_check_fix_description = check_fix_descriptions_prefix in input_text
 
     if has_check_note and has_check_message:
       sys.exit('Please use either %s or %s but not both' %
         (check_notes_prefix, check_messages_prefix))
 
-    if not has_check_fix and not has_check_message and not has_check_note:
-      sys.exit('%s, %s or %s not found in the input' %
-        (check_fixes_prefix, check_messages_prefix, check_notes_prefix))
+    if not has_check_fix and not has_check_message and not has_check_note and \
+      not has_check_fix_description:
+      sys.exit('%s, %s, %s or %s not found in the input' %
+        (check_fixes_prefix, check_messages_prefix, check_notes_prefix,
+          check_fix_descriptions_prefix))
 
     has_check_fixes = has_check_fixes or has_check_fix
     has_check_messages = has_check_messages or has_check_message
     has_check_notes = has_check_notes or has_check_note
+    has_check_fix_descriptions = has_check_fix_descriptions or \
+      has_check_fix_description
 
     check_fixes_prefixes.append(check_fixes_prefix)
     check_messages_prefixes.append(check_messages_prefix)
     check_notes_prefixes.append(check_notes_prefix)
+    check_fix_descriptions_prefixes.append(check_fix_descriptions_prefix)
 
   assert has_check_fixes or has_check_messages or has_check_notes
   # Remove the contents of the CHECK lines to avoid CHECKs matching on
   # themselves.  We need to keep the comments to preserve line numbers while
   # avoiding empty lines which could potentially trigger formatting-related
   # checks.
   cleaned_test = re.sub('// *CHECK-[A-Z0-9\-]*:[^\r\n]*', '//', input_text)
 
try:
           ['FileCheck', '-input-file=' + temp_file_name, input_file_name,
            '-check-prefixes=' + ','.join(check_fixes_prefixes),
            '-strict-whitespace'],
           stderr=subprocess.STDOUT)
     except subprocess.CalledProcessError as e:
       print('FileCheck failed:\n' + e.output.decode())
       raise
 
+  if has_check_fix_descriptions:
+    try:
+      fix_descriptions_file = temp_file_name + '.fix-descriptions'
+      write_file(fix_descriptions_file, clang_tidy_output)
+      subprocess.check_output(
+          ['FileCheck', '-input-file=' + fix_descriptions_file, input_file_name,
+           '-check-prefixes=' + ','.join(check_fix_descriptions_prefixes)],
+          stderr=subprocess.STDOUT)
+    except subprocess.CalledProcessError as e:
+      print('FileCheck failed:\n' + e.output.decode())
+      raise
+
   if has_check_messages:
     messages_file = temp_file_name + '.msg'
     write_file(messages_file, clang_tidy_output)
     try:
       subprocess.check_output(
           ['FileCheck', '-input-file=' + messages_file, input_file_name,
            '-check-prefixes=' + ','.join(check_messages_prefixes),
            '-implicit-check-not={{warning|error}}:'],

clang-tools-extra/test/clang-tidy/misc-unused-using-decls.cpp

 T ff() { T t; return t; }
 } // namespace ns
 
 // ----- Using declarations -----
 // eol-comments aren't removed (yet)
 using n::A; // A
 // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: using decl 'A' is unused
 // CHECK-FIXES: {{^}}// A
+// CHECK-FIX-DESCRIPTIONS: :[[@LINE-3]]:10: note: remove the using
 using n::B;
 using n::C;
 using n::D;
 using n::E; // E
 // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: using decl 'E' is unused
 // CHECK-FIXES: {{^}}// E
 using n::F;
 using n::G;