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.





git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147410 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 11 insertions, 3 deletions

diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index 983673fec8..a71275a2c1 100644
--- a/lib/AST/DeclBase.cpp
+++ b/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;
diff --git a/lib/AST/DeclObjC.cpp b/lib/AST/DeclObjC.cpp
index f5828fcb4c..341f0f5e93 100644
--- a/lib/AST/DeclObjC.cpp
+++ b/lib/AST/DeclObjC.cpp
@@ -1005,11 +1005,17 @@ ObjCMethodDecl *ObjCProtocolDecl::lookupMethod(Selector Sel,
 
 void ObjCProtocolDecl::allocateDefinitionData() {
   assert(!Data && "Protocol already has a definition!");
-  Data = new (getASTContext()) DefinitionData;  
+  Data = new (getASTContext()) DefinitionData;
+  Data->Definition = this;
 }
 
 void ObjCProtocolDecl::startDefinition() {
   allocateDefinitionData();
+  
+  // Update all of the declarations with a pointer to the definition.
+  for (redecl_iterator RD = redecls_begin(), RDEnd = redecls_end();
+       RD != RDEnd; ++RD)
+    RD->Data = this->Data;
 }
 
 void ObjCProtocolDecl::completedForwardDecl() {