Function first

include/pybind11/detail/common.h:935–935

PYBIND11_NAMESPACE_BEGIN(constexpr_impl)
/// Implementation details for constexpr functions
constexpr int first(int i) { return i; }
template <typename T, typename... Ts>
constexpr int first(int i, T v, Ts... vs) {
    return v ? i : first(i + 1, vs...);