segfault

#include <vector>

struct Foo
{
    double a, b, c, d;
};

std::vector<Foo> nodes;
int left = 3;


double run()
{
    if (left == 0)
        return 1.0;

    left--;
    nodes.push_back(Foo());

    nodes[0].a = run();

    //double tmp = run();
    //nodes[0].a = tmp;

    return 1.0;
}

int main()
{
    run();
    return 0;
}