aggregate_field_count
template <typename T, std::size_t Count = 0>
constexpr std::size_t aggregate_field_count() noexceptReturns
std::size_t
Description
Returns the most initialisers T{...} accepts, counting each element of an array member.
A member added anywhere, padding included, raises it, which a sizeof guard can miss.
Precondition
T is an aggregate with fewer than 64 initialisers.