fixed_vector(const fixed_vector& other)
: holder_(other.size(), AllocTraits::select_on_container_copy_construction(other.get_allocator()))
{ std::copy(other.begin(), other.end(), std::back_inserter(*this)); }
fixed_vector(const fixed_vector<value_type, OtherAlloc>& other,
const allocator_type& alloc = allocator_type())
: holder_(other.size(), alloc)
{ std::copy(other.begin(), other.end(), std::back_inserter(*this)); }
fixed_vector(const fixed_vector& other) : m_size(other.m_size) {
std::copy(other.begin(), other.end(), begin());
}