Support C++ friend declarations for PCH.

This commit 'introduces' a slightly different way to restore the state of the AST object.
It makes PCHDeclReader/PCHDeclWriter friends and gives them access to the private members of the object.
The rationale is to avoid using/modifying the AST interfaces for PCH read/write so that to:

-Avoid complications with objects that have side-effects during creation or when using some setters.
-Not 'pollute' the AST interface with methods only used by the PCH reader/writer
-Allow AST objects to be read-only.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@107219 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 44 insertions, 9 deletions

diff --git a/lib/AST/DeclFriend.cpp b/lib/AST/DeclFriend.cpp
index ab3552db28..99bfe40c31 100644
--- a/lib/AST/DeclFriend.cpp
+++ b/lib/AST/DeclFriend.cpp
@@ -39,3 +39,7 @@ FriendDecl *FriendDecl::Create(ASTContext &C, DeclContext *DC,
   cast<CXXRecordDecl>(DC)->pushFriendDecl(FD);
   return FD;
 }
+
+FriendDecl *FriendDecl::Create(ASTContext &C, EmptyShell Empty) {
+  return new (C) FriendDecl(Empty);
+}
diff --git a/lib/Frontend/PCHReaderDecl.cpp b/lib/Frontend/PCHReaderDecl.cpp
index 05cefa9ffe..9f057b0c1d 100644
--- a/lib/Frontend/PCHReaderDecl.cpp
+++ b/lib/Frontend/PCHReaderDecl.cpp
@@ -27,7 +27,7 @@ using namespace clang;
 // Declaration deserialization
 //===----------------------------------------------------------------------===//
 
-namespace {
+namespace clang {
   class PCHDeclReader : public DeclVisitor<PCHDeclReader, void> {
     PCHReader &Reader;
     const PCHReader::RecordData &Record;
@@ -81,6 +81,7 @@ namespace {
     void VisitLinkageSpecDecl(LinkageSpecDecl *D);
     void VisitFileScopeAsmDecl(FileScopeAsmDecl *AD);
     void VisitAccessSpecDecl(AccessSpecDecl *D);
+    void VisitFriendDecl(FriendDecl *D);
     void VisitFriendTemplateDecl(FriendTemplateDecl *D);
     void VisitStaticAssertDecl(StaticAssertDecl *D);
     void VisitBlockDecl(BlockDecl *BD);
@@ -673,6 +674,9 @@ void PCHDeclReader::VisitCXXRecordDecl(CXXRecordDecl *D) {
       Bases.push_back(ReadCXXBaseSpecifier());
     D->setBases(Bases.begin(), NumBases);
 
+    D->data().FirstFriend
+        = cast_or_null<FriendDecl>(Reader.GetDecl(Record[Idx++]));
+
     // FIXME: there's a lot of stuff we do here that's kindof sketchy
     // if we're leaving the context incomplete.
     D->completeDefinition();
@@ -704,6 +708,15 @@ void PCHDeclReader::VisitAccessSpecDecl(AccessSpecDecl *D) {
   D->setColonLoc(Reader.ReadSourceLocation(Record, Idx));
 }
 
+void PCHDeclReader::VisitFriendDecl(FriendDecl *D) {
+  if (Record[Idx++])
+    D->Friend = Reader.GetTypeSourceInfo(Record, Idx);
+  else
+    D->Friend = cast<NamedDecl>(Reader.GetDecl(Record[Idx++]));
+  D->NextFriend = cast_or_null<FriendDecl>(Reader.GetDecl(Record[Idx++]));
+  D->FriendLoc = Reader.ReadSourceLocation(Record, Idx);
+}
+
 void PCHDeclReader::VisitFriendTemplateDecl(FriendTemplateDecl *D) {
   assert(false && "cannot read FriendTemplateDecl");
 }
@@ -1204,7 +1217,7 @@ Decl *PCHReader::ReadDeclRecord(uint64_t Offset, unsigned Index) {
                                SourceLocation());
     break;
   case pch::DECL_FRIEND:
-    assert(false && "cannot read FriendDecl");
+    D = FriendDecl::Create(*Context, Decl::EmptyShell());
     break;
   case pch::DECL_FRIEND_TEMPLATE:
     assert(false && "cannot read FriendTemplateDecl");
diff --git a/lib/Frontend/PCHWriter.cpp b/lib/Frontend/PCHWriter.cpp
index 8b714386c1..d947f7250d 100644
--- a/lib/Frontend/PCHWriter.cpp
+++ b/lib/Frontend/PCHWriter.cpp
@@ -1444,11 +1444,16 @@ uint64_t PCHWriter::WriteDeclContextVisibleBlock(ASTContext &Context,
   if (DC->getPrimaryContext() != DC)
     return 0;
 
-  // Since there is no name lookup into functions or methods, and we
-  // perform name lookup for the translation unit via the
-  // IdentifierInfo chains, don't bother to build a
-  // visible-declarations table for these entities.
-  if (DC->isFunctionOrMethod() || DC->isTranslationUnit())
+  // Since there is no name lookup into functions or methods, don't bother to
+  // build a visible-declarations table for these entities.
+  if (DC->isFunctionOrMethod())
+    return 0;
+
+  // If not in C++, we perform name lookup for the translation unit via the
+  // IdentifierInfo chains, don't bother to build a visible-declarations table.
+  // FIXME: In C++ we need the visible declarations in order to "see" the
+  // friend declarations, is there a way to do this without writing the table ?
+  if (DC->isTranslationUnit() && !Context.getLangOptions().CPlusPlus)
     return 0;
 
   // Force the DeclContext to build a its name-lookup table.
diff --git a/lib/Frontend/PCHWriterDecl.cpp b/lib/Frontend/PCHWriterDecl.cpp
index 42d506953c..309cc3536d 100644
--- a/lib/Frontend/PCHWriterDecl.cpp
+++ b/lib/Frontend/PCHWriterDecl.cpp
@@ -25,7 +25,7 @@ using namespace clang;
 // Declaration serialization
 //===----------------------------------------------------------------------===//
 
-namespace {
+namespace clang {
   class PCHDeclWriter : public DeclVisitor<PCHDeclWriter, void> {
 
     PCHWriter &Writer;
@@ -82,6 +82,7 @@ namespace {
     void VisitLinkageSpecDecl(LinkageSpecDecl *D);
     void VisitFileScopeAsmDecl(FileScopeAsmDecl *D);
     void VisitAccessSpecDecl(AccessSpecDecl *D);
+    void VisitFriendDecl(FriendDecl *D);
     void VisitFriendTemplateDecl(FriendTemplateDecl *D);
     void VisitStaticAssertDecl(StaticAssertDecl *D);
     void VisitBlockDecl(BlockDecl *D);
@@ -636,7 +637,6 @@ void PCHDeclWriter::WriteCXXBaseSpecifier(const CXXBaseSpecifier *Base) {
 }
 
 void PCHDeclWriter::VisitCXXRecordDecl(CXXRecordDecl *D) {
-  // assert(false && "cannot write CXXRecordDecl");
   VisitRecordDecl(D);
 
   enum {
@@ -664,6 +664,8 @@ void PCHDeclWriter::VisitCXXRecordDecl(CXXRecordDecl *D) {
     for (CXXRecordDecl::base_class_iterator I = D->bases_begin(),
            E = D->bases_end(); I != E; ++I)
       WriteCXXBaseSpecifier(&*I);
+    
+    Writer.AddDeclRef(D->data().FirstFriend, Record);
   }
   Code = pch::DECL_CXX_RECORD;
 }
@@ -698,6 +700,17 @@ void PCHDeclWriter::VisitAccessSpecDecl(AccessSpecDecl *D) {
   Code = pch::DECL_ACCESS_SPEC;
 }
 
+void PCHDeclWriter::VisitFriendDecl(FriendDecl *D) {
+  Record.push_back(D->Friend.is<TypeSourceInfo*>());
+  if (D->Friend.is<TypeSourceInfo*>())
+    Writer.AddTypeSourceInfo(D->Friend.get<TypeSourceInfo*>(), Record);
+  else
+    Writer.AddDeclRef(D->Friend.get<NamedDecl*>(), Record);
+  Writer.AddDeclRef(D->NextFriend, Record);
+  Writer.AddSourceLocation(D->FriendLoc, Record);
+  Code = pch::DECL_FRIEND;
+}
+
 void PCHDeclWriter::VisitFriendTemplateDecl(FriendTemplateDecl *D) {
   assert(false && "cannot write FriendTemplateDecl");
 }