Driver: Handle /GR- in a compatible way with MSVC

There are slight differences between /GR- and -fno-rtti which made
mapping one to the other inappropriate.

-fno-rtti disables dynamic_cast, typeid, and does not emit RTTI related
information for the v-table.

/GR- does not generate complete object locators and thus will not
reference them in vftables.  However, constructs like dynamic_cast and
typeid are permitted.

This should bring our implementation of RTTI up to semantic parity with
MSVC modulo bugs.

llvm-svn: 212138

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1447,6 +1447,7 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.TraditionalCPP = Args.hasArg(OPT_traditional_cpp);
 
   Opts.RTTI = !Args.hasArg(OPT_fno_rtti);
+  Opts.RTTIData = Opts.RTTI && !Args.hasArg(OPT_fno_rtti_data);
   Opts.Blocks = Args.hasArg(OPT_fblocks);
   Opts.BlocksRuntimeOptional = Args.hasArg(OPT_fblocks_runtime_optional);
   Opts.Modules = Args.hasArg(OPT_fmodules);