Fix the default libc++ header search path to be sysrooted. Radar 9639692.

The -cxx-isystem path is not prefixed with the sysroot directory, so it's
not a good way for the driver to set the system default C++ search path.
Instead, add -stdlib as a cc1 option and teach the frontend how to find the
headers.  The driver can then just pass -stdlib through to "cc1".

llvm-svn: 133547

2 files changed, 10 insertions, 2 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 61887e8eb2a..cf1feb7f6f2 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -553,6 +553,8 @@ static void HeaderSearchOptsToArgs(const HeaderSearchOptions &Opts,
     Res.push_back("-nostdinc");
   if (!Opts.UseStandardCXXIncludes)
     Res.push_back("-nostdinc++");
+  if (Opts.UseLibcxx)
+    Res.push_back("-stdlib=libc++");
   if (Opts.Verbose)
     Res.push_back("-v");
 }
@@ -1330,6 +1332,8 @@ static void ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args) {
   Opts.UseBuiltinIncludes = !Args.hasArg(OPT_nobuiltininc);
   Opts.UseStandardIncludes = !Args.hasArg(OPT_nostdinc);
   Opts.UseStandardCXXIncludes = !Args.hasArg(OPT_nostdincxx);
+  if (const Arg *A = Args.getLastArg(OPT_stdlib_EQ))
+    Opts.UseLibcxx = (strcmp(A->getValue(Args), "libc++") == 0);
   Opts.ResourceDir = Args.getLastArgValue(OPT_resource_dir);
 
   // Add -I... and -F... options in order.
diff --git a/clang/lib/Frontend/InitHeaderSearch.cpp b/clang/lib/Frontend/InitHeaderSearch.cpp
index f94edc65b98..238ff7fdc8a 100644
--- a/clang/lib/Frontend/InitHeaderSearch.cpp
+++ b/clang/lib/Frontend/InitHeaderSearch.cpp
@@ -920,8 +920,12 @@ AddDefaultCPlusPlusIncludePaths(const llvm::Triple &triple) {
 void InitHeaderSearch::AddDefaultSystemIncludePaths(const LangOptions &Lang,
                                                     const llvm::Triple &triple,
                                             const HeaderSearchOptions &HSOpts) {
-  if (Lang.CPlusPlus && HSOpts.UseStandardCXXIncludes)
-    AddDefaultCPlusPlusIncludePaths(triple);
+  if (Lang.CPlusPlus && HSOpts.UseStandardCXXIncludes) {
+    if (HSOpts.UseLibcxx)
+      AddPath("/usr/include/c++/v1", CXXSystem, true, false, false);
+    else
+      AddDefaultCPlusPlusIncludePaths(triple);
+  }
 
   AddDefaultCIncludePaths(triple, HSOpts);