Teach DeclContext how to find the primary declaration for any TagDecl

even when we are still defining the TagDecl. This is required so that
qualified name lookup of a class name within its definition works (see
the new bits in test/SemaCXX/qualified-id-lookup.cpp).

As part of this, move the nested redefinition checking code into
ActOnTag. This gives us diagnostics earlier (when we try to perform
the nested redefinition, rather than when we try to complete the 2nd
definition) and removes some code duplication.

llvm-svn: 62386

1 files changed, 16 insertions, 12 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 0bc0043ccb8..8ae93110170 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -144,13 +144,8 @@ void EnumDecl::Destroy(ASTContext& C) {
 
 void EnumDecl::completeDefinition(ASTContext &C, QualType NewType) {
   assert(!isDefinition() && "Cannot redefine enums!");
-  setDefinition(true);
-
   IntegerType = NewType;
-
-  // Let ASTContext know that this is the defining EnumDecl for this
-  // type.
-  C.setTagDefinition(this);
+  TagDecl::completeDefinition();
 }
 
 FileScopeAsmDecl *FileScopeAsmDecl::Create(ASTContext &C,
@@ -311,6 +306,20 @@ OverloadedOperatorKind FunctionDecl::getOverloadedOperator() const {
 // TagDecl Implementation
 //===----------------------------------------------------------------------===//
 
+void TagDecl::startDefinition() {
+  cast<TagType>(TypeForDecl)->decl.setPointer(this);
+  cast<TagType>(TypeForDecl)->decl.setInt(1);
+}
+
+void TagDecl::completeDefinition() {
+  assert((!TypeForDecl || 
+          cast<TagType>(TypeForDecl)->decl.getPointer() == this) &&
+         "Attempt to redefine a tag definition?");
+  IsDefinition = true;
+  cast<TagType>(TypeForDecl)->decl.setPointer(this);
+  cast<TagType>(TypeForDecl)->decl.setInt(0);
+}
+
 TagDecl* TagDecl::getDefinition(ASTContext& C) const {
   QualType T = C.getTypeDeclType(const_cast<TagDecl*>(this));
   TagDecl* D = cast<TagDecl>(cast<TagType>(T)->getDecl());  
@@ -351,12 +360,7 @@ void RecordDecl::Destroy(ASTContext& C) {
 /// complete.
 void RecordDecl::completeDefinition(ASTContext& C) {
   assert(!isDefinition() && "Cannot redefine record!");
-
-  setDefinition(true);
-  
-  // Let ASTContext know that this is the defining RecordDecl for this
-  // type.
-  C.setTagDefinition(this);
+  TagDecl::completeDefinition();
 }
 
 //===----------------------------------------------------------------------===//