put noisy "unknown command tag name" warning

under -Wdocumentation-unknown-command and off by default.
patch by Dmitri Gribenko.

llvm-svn: 181487

clang/include/clang/Basic/DiagnosticCommentKinds.td

@@ -157,7 +157,8 @@ def warn_verbatim_block_end_without_start : Warning<
   InGroup<Documentation>, DefaultIgnore;
 
 def warn_unknown_comment_command_name : Warning<
-  "unknown command tag name">, InGroup<Documentation>, DefaultIgnore;
+  "unknown command tag name">,
+  InGroup<DocumentationUnknownCommand>, DefaultIgnore;
 
 def warn_correct_comment_command_name : Warning<
   "unknown command tag name '%0'; did you mean '%1'?">,

clang/include/clang/Basic/DiagnosticGroups.td

@@ -68,7 +68,9 @@ def : DiagGroup<"discard-qual">;
 def : DiagGroup<"div-by-zero">;
 
 def DocumentationHTML : DiagGroup<"documentation-html">;
-def DocumentationPedantic : DiagGroup<"documentation-pedantic">;
+def DocumentationUnknownCommand : DiagGroup<"documentation-unknown-command">;
+def DocumentationPedantic : DiagGroup<"documentation-pedantic",
+                                      [DocumentationUnknownCommand]>;
 def DocumentationDeprecatedSync : DiagGroup<"documentation-deprecated-sync">;
 def Documentation : DiagGroup<"documentation",
                               [DocumentationHTML,