I have a class template which builds a simple array based on the template parameters as one of its members. I need to be able to initialize every element in the array to a single value in one of the constructors. Unfortunately this constructor must be constexpr. The relevant part boils down to: template <typename T, size_t N> class foo { T data[N]; constexpr foo(T val) { // initialize data with N copies of val } }; Using std::fill or a loop is incompatible with the constexpr requirement. Initializing with : data{val} only sets the first element of the array and zero-initializes the remainder. How can this be achieved? I feel like there should be a solution with variadic templates and tuples etc...