Introduce a new type, PackExpansionType, to capture types that are
pack expansions, e.g. given

  template<typename... Types> struct tuple;

  template<typename... Types>
  struct tuple_of_refs {
    typedef tuple<Types&...> types;
  };

the type of the "types" typedef is a PackExpansionType whose pattern
is Types&. 

This commit introduces support for creating pack expansions for
template type arguments, as above, but not for any other kind of pack
expansion, nor for any form of instantiation.

llvm-svn: 122223
diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index dd2f1cb..aa9046f 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -1140,6 +1140,10 @@
          "Don't know how to mangle DependentTemplateSpecializationTypes yet!");
 }
 
+void MicrosoftCXXNameMangler::mangleType(const PackExpansionType *T) {
+  assert(false && "Don't know how to mangle PackExpansionTypes yet!");
+}
+
 void MicrosoftCXXNameMangler::mangleType(const TypeOfType *T) {
   assert(false && "Don't know how to mangle TypeOfTypes yet!");
 }