1 files changed, 8 insertions, 1 deletions
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index ea7d9a9385..beadb588f3 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -2032,7 +2032,14 @@ Sema::DeclPtrTy Sema::ActOnProperty(Scope *S, SourceLocation AtLoc,
   ObjCPropertyDecl *PDecl = ObjCPropertyDecl::Create(Context, DC,
                                                      FD.D.getIdentifierLoc(),
                                                      FD.D.getIdentifier(), T);
-  DC->addDecl(PDecl);
+  DeclContext::lookup_result Found = DC->lookup(PDecl->getDeclName());
+  if (Found.first != Found.second && isa<ObjCPropertyDecl>(*Found.first)) {
+    Diag(PDecl->getLocation(), diag::err_duplicate_property);
+    Diag((*Found.first)->getLocation(), diag::note_property_declare);
+    PDecl->setInvalidDecl();
+  }
+  else
+    DC->addDecl(PDecl);
 
   if (T->isArrayType() || T->isFunctionType()) {
     Diag(AtLoc, diag::err_property_type) << T;