PR9023: A template template parameter whose template parameter list contains an

unexpanded parameter pack is a pack expansion. Thus, as with a non-type template
parameter which is a pack expansion, it needs to be expanded early into a fixed
list of template parameters.

Since the expanded list of template parameters is not itself a parameter pack,
it is permitted to appear before the end of the template parameter list, so also
remove that restriction (for both template template parameter pack expansions and
non-type template parameter pack expansions).

llvm-svn: 163369

1 files changed, 22 insertions, 6 deletions

diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index 602943b9ba5..baa8a0e4cd4 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -1172,7 +1172,8 @@ void ASTDeclWriter::VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D) {
 
 void ASTDeclWriter::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
   // For an expanded parameter pack, record the number of expansion types here
-  // so that it's easier for 
+  // so that it's easier for deserialization to allocate the right amount of
+  // memory.
   if (D->isExpandedParameterPack())
     Record.push_back(D->getNumExpansionTypes());
   
@@ -1201,15 +1202,30 @@ void ASTDeclWriter::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
 }
 
 void ASTDeclWriter::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
+  // For an expanded parameter pack, record the number of expansion types here
+  // so that it's easier for deserialization to allocate the right amount of
+  // memory.
+  if (D->isExpandedParameterPack())
+    Record.push_back(D->getNumExpansionTemplateParameters());
+
   VisitTemplateDecl(D);
   // TemplateParmPosition.
   Record.push_back(D->getDepth());
   Record.push_back(D->getPosition());
-  // Rest of TemplateTemplateParmDecl.
-  Writer.AddTemplateArgumentLoc(D->getDefaultArgument(), Record);
-  Record.push_back(D->defaultArgumentWasInherited());
-  Record.push_back(D->isParameterPack());
-  Code = serialization::DECL_TEMPLATE_TEMPLATE_PARM;
+
+  if (D->isExpandedParameterPack()) {
+    for (unsigned I = 0, N = D->getNumExpansionTemplateParameters();
+         I != N; ++I)
+      Writer.AddTemplateParameterList(D->getExpansionTemplateParameters(I),
+                                      Record);
+    Code = serialization::DECL_EXPANDED_TEMPLATE_TEMPLATE_PARM_PACK;
+  } else {
+    // Rest of TemplateTemplateParmDecl.
+    Writer.AddTemplateArgumentLoc(D->getDefaultArgument(), Record);
+    Record.push_back(D->defaultArgumentWasInherited());
+    Record.push_back(D->isParameterPack());
+    Code = serialization::DECL_TEMPLATE_TEMPLATE_PARM;
+  }
 }
 
 void ASTDeclWriter::VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D) {