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.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148323 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index 4016c20..01177fa 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -2225,6 +2225,7 @@
   friend class TagDecl;
   friend class TemplateTypeParmDecl;
   friend class TagType;
+  friend class ASTReader;
 
 protected:
   TypeDecl(Kind DK, DeclContext *DC, SourceLocation L, IdentifierInfo *Id,
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index 436c02c..ed2e837 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -3070,6 +3070,8 @@
   /// TagDecl that declares the entity.
   TagDecl * decl;
 
+  friend class ASTReader;
+  
 protected:
   TagType(TypeClass TC, const TagDecl *D, QualType can);
 
@@ -4160,6 +4162,7 @@
     : ObjCObjectType(Nonce_ObjCInterface),
       Decl(const_cast<ObjCInterfaceDecl*>(D)) {}
   friend class ASTContext;  // ASTContext creates these.
+  friend class ASTReader;
   friend class ObjCInterfaceDecl;
 
 public:
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 57cd021..245e8b1 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -3901,8 +3901,9 @@
     }
     unsigned Idx = 0;
     bool IsDependent = Record[Idx++];
-    QualType T
-      = Context.getRecordType(ReadDeclAs<RecordDecl>(*Loc.F, Record, Idx));
+    RecordDecl *RD = 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 @@
     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 @@
     // 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 @@
   for (llvm::SmallPtrSet<Decl *, 4>::iterator D = PendingDefinitions.begin(),
                                            DEnd = PendingDefinitions.end();
        D != DEnd; ++D) {
-    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;
+    if (TagDecl *TD = dyn_cast<TagDecl>(*D)) {
+      if (const TagType *TagT = dyn_cast<TagType>(TD->TypeForDecl)) {
+        // Make sure that the TagType points at the definition.
+        const_cast<TagType*>(TagT)->decl = TD;
+      }
       
+      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)
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 7a09b32..c5f9b2d 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -239,7 +239,7 @@
 
 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::VisitObjCInterfaceType(const ObjCInterfaceType *T) {
-  Writer.AddDeclRef(T->getDecl(), Record);
+  Writer.AddDeclRef(T->getDecl()->getCanonicalDecl(), Record);
   Code = TYPE_OBJC_INTERFACE;
 }