C++11 non-type template parameter bundle expansion

Question

While working with C++11 template parameter bundles, I came up with the code below:

#include <cstdio>

static void testFunc(int i1, int i2) {
    printf("testFunc(%d, %d)\n", i1, i2);
}

template <size_t... Indices> void wrapper() {
    testFunc(Indices...);
}

int main(int argc, char *argv[]) {
    wrapper<1, 2>();    
    return 0;
}

An attempt to compile this with g++4.8.2 resulted in a "too few arguments to function ‘void testFunc(int, int)’" error.

Is this no valid C++ or does g++ just not yet implement this kind of non-type template parameter bundle usage?

Answer 1

It's valid and this appears to be a bug in gcc's variadic templates implementation. I searched a bit on the gcc bugzilla page and did not find any reports of this issue.

Answer 2

I guess as a workaround you can do this:

template <size_t... Indices> void wrapper() {
    constexpr int x[] = {Indices...};
    testFunc(x[0], x[1]);
}