[PATCH] Enable layering check in unavailable modules

[Dmitri Gribenko]

================
Comment at: lib/Lex/ModuleMap.cpp:165-166
@@ -166,8 +164,4 @@
   HeadersMap::iterator Known = Headers.find(File);
-
-  // If we've found a builtin header within Clang's builtin include directory,
-  // load all of the module maps to see if it will get associated with a
-  // specific module (e.g., in /usr/include).
   if (Known == Headers.end() && File->getDir() == BuiltinIncludeDir &&
       isBuiltinHeader(llvm::sys::path::filename(File->getName()))) {
     HeaderInfo.loadTopLevelSystemModules();
----------------
Why do we need the isBuiltinHeader() check?  It returns false for some builtin headers, for example, xmmintrin.h.



http://llvm-reviews.chandlerc.com/D2442