[c++1z] P0195R2: Support pack-expansion of using-declarations.

This change introduces UsingPackDecl as a marker for the set of UsingDecls
produced by pack expansion of a single (unresolved) using declaration. This is
not strictly necessary (we just need to be able to map from the original using
declaration to its expansions somehow), but it's useful to maintain the
invariant that each declaration reference instantiates to refer to one
declaration.

llvm-svn: 290080

1 files changed, 15 insertions, 0 deletions

diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 913a1419b3f..dc29a61c0a9 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -322,6 +322,7 @@ namespace clang {
     void VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
     void VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D);
     void VisitUsingDecl(UsingDecl *D);
+    void VisitUsingPackDecl(UsingPackDecl *D);
     void VisitUsingShadowDecl(UsingShadowDecl *D);
     void VisitConstructorUsingShadowDecl(ConstructorUsingShadowDecl *D);
     void VisitLinkageSpecDecl(LinkageSpecDecl *D);
@@ -1419,6 +1420,15 @@ void ASTDeclReader::VisitUsingDecl(UsingDecl *D) {
   mergeMergeable(D);
 }
 
+void ASTDeclReader::VisitUsingPackDecl(UsingPackDecl *D) {
+  VisitNamedDecl(D);
+  D->InstantiatedFrom = ReadDeclAs<NamedDecl>();
+  NamedDecl **Expansions = D->getTrailingObjects<NamedDecl*>();
+  for (unsigned I = 0; I != D->NumExpansions; ++I)
+    Expansions[I] = ReadDeclAs<NamedDecl>();
+  mergeMergeable(D);
+}
+
 void ASTDeclReader::VisitUsingShadowDecl(UsingShadowDecl *D) {
   RedeclarableResult Redecl = VisitRedeclarable(D);
   VisitNamedDecl(D);
@@ -1452,6 +1462,7 @@ void ASTDeclReader::VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D) {
   D->setUsingLoc(ReadSourceLocation());
   D->QualifierLoc = Record.ReadNestedNameSpecifierLoc(Idx);
   ReadDeclarationNameLoc(D->DNLoc, D->getDeclName());
+  D->EllipsisLoc = ReadSourceLocation();
   mergeMergeable(D);
 }
 
@@ -1460,6 +1471,7 @@ void ASTDeclReader::VisitUnresolvedUsingTypenameDecl(
   VisitTypeDecl(D);
   D->TypenameLocation = ReadSourceLocation();
   D->QualifierLoc = Record.ReadNestedNameSpecifierLoc(Idx);
+  D->EllipsisLoc = ReadSourceLocation();
   mergeMergeable(D);
 }
 
@@ -3297,6 +3309,9 @@ Decl *ASTReader::ReadDeclRecord(DeclID ID) {
   case DECL_USING:
     D = UsingDecl::CreateDeserialized(Context, ID);
     break;
+  case DECL_USING_PACK:
+    D = UsingPackDecl::CreateDeserialized(Context, ID, Record[Idx++]);
+    break;
   case DECL_USING_SHADOW:
     D = UsingShadowDecl::CreateDeserialized(Context, ID);
     break;