Introduce the core infrastructure needed to model redeclaration chains

for Objective-C protocols, including:
  - Using the first declaration as the canonical declaration
  - Using the definition as the primary DeclContext
  - Making sure that all declarations have a pointer to the definition
  data, and that we know which declaration is the definition
  - Serialization support for redeclaration chains and for adding
  definitions to already-serialized declarations.

However, note that we're not taking advantage of much of this code
yet, because we're still re-using ObjCProtocolDecls.

llvm-svn: 147410

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 983673fec8f..a71275a2c1f 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -784,8 +784,10 @@ DeclContext *DeclContext::getPrimaryContext() {
     return this;
       
   case Decl::ObjCProtocol:
-    // FIXME: Update when protocols properly model forward declarations.
-    // For now, it's fine to fall through
+    if (ObjCProtocolDecl *Def = cast<ObjCProtocolDecl>(this)->getDefinition())
+      return Def;
+    
+    return this;
       
   case Decl::ObjCCategory:
     return this;