Same as the constructor taking pair<PARAM_1, PARAM_2>&&.
Declared in <bslstl_pair.h>
template<
class PARAM_1,
class PARAM_2,
class = void>
requires bsl::is_convertible<PARAM_1, T1>::value
&& bsl::is_convertible<PARAM_2, T2>::value
constexpr
pair(std::pair<PARAM_1, PARAM_2>&& other);