c++ 11 deduction of uniform initializer_list

#include <iostream>    
#include <boost/type_index.hpp>
using boost::typeindex::type_id_with_cvr;
#define print_type(var) do { \
  std::cout << type_id_with_cvr<decltype(var)>().pretty_name() \
            << std::endl; \
} while(0)

int main() {   
  auto il1 = { 1 };
  auto il2{ 1 };
  print_type(il1);
  print_type(il2);
  return 0;
}

output

$ ./item2 
std::initializer_list<int>
int

I expected every output is initializer_list. But the second is deduced to the just int type.

• tested with g++ 5.4, clang 3.8, clang 4.0.
• built using clang++ -std=c++11 ../item2.cpp or -std=gnu++11

Could somebody explain this issue?