clang-cl: Fall back immediately if /GR and /fallback were both passed

None of our tests use /fallback, so this lets us gradually add RTTI
support without breaking projects using /fallback.

llvm-svn: 208787

1 files changed, 9 insertions, 1 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 1f9e12bb538..afef7008fad 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -4106,7 +4106,15 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     tools::visualstudio::Compile CL(getToolChain());
     Command *CLCommand = CL.GetCommand(C, JA, Output, Inputs, Args,
                                        LinkingOutput);
-    C.addCommand(new FallbackCommand(JA, *this, Exec, CmdArgs, CLCommand));
+    // RTTI support in clang-cl is a work in progress.  Fall back to MSVC early
+    // if we are using 'clang-cl /fallback /GR'.
+    // FIXME: Remove this when RTTI is finished.
+    if (Args.hasFlag(options::OPT_frtti, options::OPT_fno_rtti, false)) {
+      D.Diag(diag::warn_drv_rtti_fallback) << CLCommand->getExecutable();
+      C.addCommand(CLCommand);
+    } else {
+      C.addCommand(new FallbackCommand(JA, *this, Exec, CmdArgs, CLCommand));
+    }
   } else {
     C.addCommand(new Command(JA, *this, Exec, CmdArgs));
   }