From StackOverflow (http://stackoverflow.com/q/44015848/2069064), this code:

#include <cstdio>
#include <initializer_list>

struct S {
  S() { std::printf("DEF "); }      // (1)
  S(std::initializer_list<int> il)  // (2)
    { std::printf("L=%zu ", il.size()); }
};

int main() {
  S x({});
}

in gcc 7.1 with -std=c++1z invokes the default constructor. In C++14 mode, it invokes the initializer_list constructor, as does clang in both modes. But the default constructor shouldn't be invoked, since {} isn't an expression so the "guaranteed elision" bullet in dcl.init shouldn't apply.