I managed to get this one in. the rationale being that -Wno-#warnings, while highly descriptive, is a total bitch to pass through shell-scripts, configure, makefiles... and gcc names the same option -Wno-cpp anyway.
okay ? Index: DiagnosticGroups.td =================================================================== RCS file: /cvs/src/gnu/llvm/tools/clang/include/clang/Basic/DiagnosticGroups.td,v retrieving revision 1.1.1.3 diff -u -p -r1.1.1.3 DiagnosticGroups.td --- DiagnosticGroups.td 24 Jan 2017 08:33:03 -0000 1.1.1.3 +++ DiagnosticGroups.td 2 Jun 2017 10:16:32 -0000 @@ -719,6 +719,7 @@ def Pedantic : DiagGroup<"pedantic">; // Aliases. def : DiagGroup<"", [Extra]>; // -W = -Wextra def : DiagGroup<"endif-labels", [ExtraTokens]>; // -Wendif-labels=-Wextra-tokens +def : DiagGroup<"cpp", [PoundWarning]>; // -Wcpp = -W#warnings def : DiagGroup<"comments", [Comment]>; // -Wcomments = -Wcomment def : DiagGroup<"conversion-null", [NullConversion]>; // -Wconversion-null = -Wnull-conversion