another pack expansion type. This can happen when rebuilding types in
the current instantiation.
Fixes <rdar://problem/8848837> (Clang crashing on libc++ <functional>).
llvm-svn: 123316
template argument corresponding to a template parameter pack is an
argument pack of a pack expansion of that template parameter
pack. Implements C++0x [temp.dep.type]p2 (at least, as much of it as
we can).
llvm-svn: 122498
Richard Smith