Skip transparent contexts when looking for using directives in name lookup.

Fixes the bootstrap regression I introduced in r179067.

llvm-svn: 179079

clang/lib/Sema/SemaLookup.cpp

@@ -962,8 +962,12 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
           // If we haven't handled using directives yet, do so now.
           if (!VisitedUsingDirectives) {
             // Add using directives from this context up to the top level.
-            for (DeclContext *UCtx = Ctx; UCtx; UCtx = UCtx->getParent())
+            for (DeclContext *UCtx = Ctx; UCtx; UCtx = UCtx->getParent()) {
+              if (UCtx->isTransparentContext())
+                continue;
+
               UDirs.visit(UCtx, UCtx);
+            }
 
             // Find the innermost file scope, so we can add using directives
             // from local scopes.

clang/test/CXX/basic/basic.lookup/basic.lookup.unqual/p14.cpp

@@ -56,12 +56,16 @@ namespace Other {
 namespace M2 {
   using namespace Other;
 
+  extern "C" {
     namespace MInner {
+      extern "C" {
         class Bar { 
           void bar();
         };
       }
     }
+  }
+}
 
 void M2::MInner::Bar::bar() {
   other_foo();