https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107206
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The aggregate copy is intended, because std::optional<T> must have a trivial
copy constructor if T has a trivial copy constructor.
There should be no uninitialized value, because the std::optional<T>'s storage
member has a default constructor that inits the first member of the union (an
empty struct):
struct _Empty_byte { };
template<typename _Up, bool = is_trivially_destructible_v<_Up>>
union _Storage
{
constexpr _Storage() noexcept : _M_empty() { }
// ...
_Empty_byte _M_empty;
_Up _M_value;
};
The compiler seems to be eliding the _M_empty() initialization, because
_M_empty has no value bits, it's all padding.
