Fix <rdar://problem/6329769> [sema] crash on duplication definition of interface with protocols.

As soon as we detect duplicate interfaces, discontinue further semantic checks (returning the original interface).

This is now consistent with how we handle protocols (and less error prone in general).

llvm-svn: 59541

1 files changed, 6 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaDeclObjC.cpp b/clang/lib/Sema/SemaDeclObjC.cpp
index 8eeb2d367d7..49b990906a2 100644
--- a/clang/lib/Sema/SemaDeclObjC.cpp
+++ b/clang/lib/Sema/SemaDeclObjC.cpp
@@ -75,9 +75,12 @@ ActOnStartClassInterface(SourceLocation AtInterfaceLoc,
   ObjCInterfaceDecl* IDecl = dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl);
   if (IDecl) {
     // Class already seen. Is it a forward declaration?
-    if (!IDecl->isForwardDecl())
+    if (!IDecl->isForwardDecl()) {
       Diag(AtInterfaceLoc, diag::err_duplicate_class_def, IDecl->getName());
-    else {
+      // Return the previous class interface.
+      // FIXME: don't leak the objects passed in!
+      return IDecl;
+    } else {
       IDecl->setLocation(AtInterfaceLoc);
       IDecl->setForwardDecl(false);
     }
@@ -119,7 +122,7 @@ ActOnStartClassInterface(SourceLocation AtInterfaceLoc,
     IDecl->setLocEnd(ClassLoc);
   }
   
-  /// Check then save referenced protocols
+  /// Check then save referenced protocols.
   if (NumProtoRefs) {
     IDecl->addReferencedProtocols((ObjCProtocolDecl**)ProtoRefs, NumProtoRefs);
     IDecl->setLocEnd(EndProtoLoc);