Rework the way in which we (de-)serialize the declarations

corresponding to TagType and ObjCInterfaceType. Previously, we would
serialize the definition (if available) or the canonical declaration
(if no definition was available). However, this can end up forcing the
deserialization of the definition even through we might not want to
yet. 

Instead, always serialize the canonical declaration reference in the
TagType/ObjCInterfaceType entry, and as part of loading a pending
definition, update the "decl" pointer within the type node to point at
the definition. This is more robust in hard-to-isolate cases
where the *Type gets built and filled in before we see the definition.

llvm-svn: 148323

clang/include/clang/AST/Decl.h

@@ -2225,6 +2225,7 @@ class TypeDecl : public NamedDecl {
   friend class TagDecl;
   friend class TemplateTypeParmDecl;
   friend class TagType;
+  friend class ASTReader;
 
 protected:
   TypeDecl(Kind DK, DeclContext *DC, SourceLocation L, IdentifierInfo *Id,

clang/include/clang/AST/Type.h

@@ -3070,6 +3070,8 @@ class TagType : public Type {
   /// TagDecl that declares the entity.
   TagDecl * decl;
 
+  friend class ASTReader;
+  
 protected:
   TagType(TypeClass TC, const TagDecl *D, QualType can);
 
@@ -4160,6 +4162,7 @@ class ObjCInterfaceType : public ObjCObjectType {
     : ObjCObjectType(Nonce_ObjCInterface),
       Decl(const_cast<ObjCInterfaceDecl*>(D)) {}
   friend class ASTContext;  // ASTContext creates these.
+  friend class ASTReader;
   friend class ObjCInterfaceDecl;
 
 public:

clang/lib/Serialization/ASTReader.cpp

@@ -3901,8 +3901,9 @@ QualType ASTReader::readTypeRecord(unsigned Index) {
     }
     unsigned Idx = 0;
     bool IsDependent = Record[Idx++];
-    QualType T
+    RecordDecl *RD = ReadDeclAs<RecordDecl>(*Loc.F, Record, Idx);
-      = Context.getRecordType(ReadDeclAs<RecordDecl>(*Loc.F, Record, Idx));
+    RD = cast_or_null<RecordDecl>(RD->getCanonicalDecl());
+    QualType T = Context.getRecordType(RD);
     const_cast<Type*>(T.getTypePtr())->setDependent(IsDependent);
     return T;
   }
@@ -3966,7 +3967,7 @@ QualType ASTReader::readTypeRecord(unsigned Index) {
     unsigned Idx = 0;
     ObjCInterfaceDecl *ItfD
       = ReadDeclAs<ObjCInterfaceDecl>(*Loc.F, Record, Idx);
-    return Context.getObjCInterfaceType(ItfD);
+    return Context.getObjCInterfaceType(ItfD->getCanonicalDecl());
   }
 
   case TYPE_OBJC_OBJECT: {
@@ -6124,6 +6125,7 @@ void ASTReader::finishPendingActions() {
     // Load pending declaration chains.
     for (unsigned I = 0; I != PendingDeclChains.size(); ++I) {
       loadPendingDeclChain(PendingDeclChains[I]);
+      PendingDeclChainsKnown.erase(PendingDeclChains[I]);
     }
     PendingDeclChains.clear();
     
@@ -6143,16 +6145,28 @@ void ASTReader::finishPendingActions() {
   for (llvm::SmallPtrSet<Decl *, 4>::iterator D = PendingDefinitions.begin(),
                                            DEnd = PendingDefinitions.end();
        D != DEnd; ++D) {
-    if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(*D)) {
+    if (TagDecl *TD = dyn_cast<TagDecl>(*D)) {
-      for (CXXRecordDecl::redecl_iterator R = RD->redecls_begin(),
+      if (const TagType *TagT = dyn_cast<TagType>(TD->TypeForDecl)) {
-                                       REnd = RD->redecls_end();
+        // Make sure that the TagType points at the definition.
-           R != REnd; ++R)
+        const_cast<TagType*>(TagT)->decl = TD;
-        cast<CXXRecordDecl>(*R)->DefinitionData = RD->DefinitionData;
+      }
       
+      if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(*D)) {
+        for (CXXRecordDecl::redecl_iterator R = RD->redecls_begin(),
+                                         REnd = RD->redecls_end();
+             R != REnd; ++R)
+          cast<CXXRecordDecl>(*R)->DefinitionData = RD->DefinitionData;
+        
+      }
+
       continue;
     }
     
     if (ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(*D)) {
+      // Make sure that the ObjCInterfaceType points at the definition.
+      const_cast<ObjCInterfaceType *>(cast<ObjCInterfaceType>(ID->TypeForDecl))
+        ->Decl = ID;
+      
       for (ObjCInterfaceDecl::redecl_iterator R = ID->redecls_begin(),
                                            REnd = ID->redecls_end();
            R != REnd; ++R)

clang/lib/Serialization/ASTWriter.cpp

@@ -239,7 +239,7 @@ void ASTTypeWriter::VisitAutoType(const AutoType *T) {
 
 void ASTTypeWriter::VisitTagType(const TagType *T) {
   Record.push_back(T->isDependentType());
-  Writer.AddDeclRef(T->getDecl(), Record);
+  Writer.AddDeclRef(T->getDecl()->getCanonicalDecl(), Record);
   assert(!T->isBeingDefined() &&
          "Cannot serialize in the middle of a type definition");
 }
@@ -369,7 +369,7 @@ void ASTTypeWriter::VisitInjectedClassNameType(const InjectedClassNameType *T) {
 }
 
 void ASTTypeWriter::VisitObjCInterfaceType(const ObjCInterfaceType *T) {
-  Writer.AddDeclRef(T->getDecl(), Record);
+  Writer.AddDeclRef(T->getDecl()->getCanonicalDecl(), Record);
   Code = TYPE_OBJC_INTERFACE;
 }