reject sizeof(itf) when itf is a forward declared interface, or when
in non-fragile abi mode.  rdar://6811884


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@69701 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 788361b..b6f1afb 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1225,7 +1225,22 @@
       << (isSizeof ? "sizeof" : "__alignof") << ExprRange;
     return false;
   }
+  
+  // sizeof(interface) and sizeof(interface<proto>)
+  if (const ObjCInterfaceType *IIT = exprType->getAsObjCInterfaceType()) {
+    if (IIT->getDecl()->isForwardDecl()) {
+      Diag(OpLoc, diag::err_sizeof_forward_interface)
+        << IIT->getDecl()->getDeclName() << isSizeof;
+      return true;
+    }
 
+    if (LangOpts.ObjCNonFragileABI) {
+      Diag(OpLoc, diag::err_sizeof_nonfragile_interface)
+        << IIT->getDecl()->getDeclName() << isSizeof;
+      return true;
+    }
+  }
+    
   return RequireCompleteType(OpLoc, exprType,
                                 isSizeof ? diag::err_sizeof_incomplete_type : 
                                            diag::err_alignof_incomplete_type,