Compilation failure on template argument pack expansion

Hi,

I've stumbled across a problem where icpc fails to correctly interpret a template argument list expansion. In particular, the problem occurs when a struct is templated on a variadic template argument list and that list is then expanded into a non-trivial expression like std::shared_ptr<T>... as part of a method signature.

Here is a small example:

#include <memory>
#include <tuple>
 
template<typename... T>
struct A
{
 
  A(std::shared_ptr<T>... t)
    : _t(t...)
  {}
 
  std::tuple<std::shared_ptr<T>...> _t;
 
};
 
int main()
{
  A<int,double> a(std::make_shared<int>(3),std::make_shared<double>(3.1));
  return 0;
}

Compiling that code works fine on both GCC 4.8.1 and clang 3.4, but fails with ICC (icpc (ICC) 14.0.1 20131008). All compilation was on Linux. The error is:

$ icpc -std=c++11 parameterpack.cc 
parameterpack.cc(8): error: parameter pack "T" was referenced but not expanded
    A(std::shared_ptr<T>... t)
                      ^
 
parameterpack.cc(8): error: pack expansion does not make use of any argument packs
    A(std::shared_ptr<T>... t)
                        ^
 
parameterpack.cc(18): error: no instance of constructor "A<T...>::A [with T=<int, double>]" matches the argument list
            argument types are: (std::shared_ptr<int>, std::shared_ptr<double>)
    A<int,double> a(std::make_shared<int>(3),std::make_shared<double>(3.1));
                    ^
 
compilation aborted for parameterpack.cc (code 2)

If you take out the shared_ptr and just use the plain parameter pack in both the constructor signature and the tuple, ICC manages to compile the code.