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, 19 insertions, 0 deletions

diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index cfc83f7bc0a..e59a3d39d16 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -3483,6 +3483,7 @@ void ASTWriter::ResolveDeclUpdatesBlocks() {
       case UPD_CXX_ADDED_TEMPLATE_SPECIALIZATION:
       case UPD_CXX_ADDED_ANONYMOUS_NAMESPACE:
       case UPD_OBJC_SET_CLASS_DEFINITIONDATA:
+      case UPD_OBJC_SET_PROTOCOL_DEFINITIONDATA:
         URec[Idx] = GetDeclRef(reinterpret_cast<Decl *>(URec[Idx]));
         ++Idx;
         break;
@@ -4447,6 +4448,24 @@ void ASTWriter::CompletedObjCForwardRef(const ObjCContainerDecl *D) {
       }
     }
   }
+
+  if (const ObjCProtocolDecl *PD = dyn_cast<ObjCProtocolDecl>(D)) {
+    for (ObjCProtocolDecl::redecl_iterator I = PD->redecls_begin(), 
+                                           E = PD->redecls_end(); 
+         I != E; ++I) {
+      if (*I == PD)
+        continue;
+      
+      // We are interested when a PCH decl is modified.
+      if (I->isFromASTFile()) {
+        UpdateRecord &Record = DeclUpdates[*I];
+        Record.push_back(UPD_OBJC_SET_PROTOCOL_DEFINITIONDATA);
+        assert((*I)->hasDefinition());
+        assert((*I)->getDefinition() == D);
+        Record.push_back(reinterpret_cast<uint64_t>(D)); // the DefinitionDecl
+      }
+    }
+  }
 }
 
 void ASTWriter::AddedObjCPropertyInClassExtension(const ObjCPropertyDecl *Prop,