2 files changed, 10 insertions, 1 deletions
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index eaa8b58b41d..ff8acde9951 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1065,7 +1065,7 @@ void CodeGenModule::EmitTopLevelDecl(Decl *D) {
     break;
   }
   case Decl::ObjCCompatibleAlias: 
-    ErrorUnsupported(D, "Objective-C compatible alias");
+    // compatibility-alias is a directive and has no code gen.
     break;
 
   case Decl::LinkageSpec: {
diff --git a/clang/lib/Sema/SemaDeclObjC.cpp b/clang/lib/Sema/SemaDeclObjC.cpp
index c32a806b7d1..68e7744582c 100644
--- a/clang/lib/Sema/SemaDeclObjC.cpp
+++ b/clang/lib/Sema/SemaDeclObjC.cpp
@@ -159,6 +159,15 @@ Sema::DeclTy *Sema::ActOnCompatiblityAlias(SourceLocation AtLoc,
   }
   // Check for class declaration
   Decl *CDeclU = LookupDecl(ClassName, Decl::IDNS_Ordinary, TUScope);
+  if (const TypedefDecl *TDecl = dyn_cast_or_null<TypedefDecl>(CDeclU)) {
+    QualType T = TDecl->getUnderlyingType();
+    if (T->isObjCInterfaceType()) {
+      if (NamedDecl *IDecl = T->getAsObjCInterfaceType()->getDecl()) {
+        ClassName = IDecl->getIdentifier();
+        CDeclU = LookupDecl(ClassName, Decl::IDNS_Ordinary, TUScope);
+      }
+    }
+  }
   ObjCInterfaceDecl *CDecl = dyn_cast_or_null<ObjCInterfaceDecl>(CDeclU);
   if (CDecl == 0) {
     Diag(ClassLocation, diag::warn_undef_interface) << ClassName;