Darwin: pass -stdlib=libc++ down to cc1 whenever we're targeting libc++

Recent refactoring meant it only got passed down when explicitly specified,
which breaks header search on Darwin.

llvm-svn: 260755

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/Driver/ToolChains.cpp b/clang/lib/Driver/ToolChains.cpp
index a357863b8fa..6ce84daec11 100644
--- a/clang/lib/Driver/ToolChains.cpp
+++ b/clang/lib/Driver/ToolChains.cpp
@@ -1030,6 +1030,7 @@ DerivedArgList *Darwin::TranslateArgs(const DerivedArgList &Args,
                                       const char *BoundArch) const {
   // First get the generic Apple args, before moving onto Darwin-specific ones.
   DerivedArgList *DAL = MachO::TranslateArgs(Args, BoundArch);
+  const OptTable &Opts = getDriver().getOpts();
 
   // If no architecture is bound, none of the translations here are relevant.
   if (!BoundArch)
@@ -1060,6 +1061,11 @@ DerivedArgList *Darwin::TranslateArgs(const DerivedArgList &Args,
     }
   }
 
+  if (!Args.getLastArg(options::OPT_stdlib_EQ) &&
+      GetDefaultCXXStdlibType() == ToolChain::CST_Libcxx)
+    DAL->AddJoinedArg(nullptr, Opts.getOption(options::OPT_stdlib_EQ),
+                      "libc++");
+
   // Validate the C++ standard library choice.
   CXXStdlibType Type = GetCXXStdlibType(*DAL);
   if (Type == ToolChain::CST_Libcxx) {