clang-cl: Fix unused argument warning when combining /O2 and /Ob2

llvm-svn: 270642

1 files changed, 6 insertions, 1 deletions

diff --git a/clang/lib/Driver/MSVCToolChain.cpp b/clang/lib/Driver/MSVCToolChain.cpp
index fb8d20be2f1..190df24e5a0 100644
--- a/clang/lib/Driver/MSVCToolChain.cpp
+++ b/clang/lib/Driver/MSVCToolChain.cpp
@@ -819,7 +819,12 @@ MSVCToolChain::TranslateArgs(const llvm::opt::DerivedArgList &Args,
       continue;
     StringRef OptStr = A->getValue();
     for (size_t I = 0, E = OptStr.size(); I != E; ++I) {
-      const char &OptChar = *(OptStr.data() + I);
+      char OptChar = OptStr[I];
+      char PrevChar = I > 0 ? OptStr[I - 1] : '0';
+      if (PrevChar == 'b') {
+        // OptChar does not expand; it's an argument to the previous char.
+        continue;
+      }
       if (OptChar == '1' || OptChar == '2' || OptChar == 'x' || OptChar == 'd')
         ExpandChar = OptStr.data() + I;
     }