取自type_traits
的GCC实施,为什么这里需要static_cast
?
template <typename _Tp, typename... _Args>
struct __is_nt_constructible_impl
: public integral_constant<bool, noexcept(_Tp(declval<_Args>()...))> {};
template <typename _Tp, typename _Arg>
struct __is_nt_constructible_impl<_Tp, _Arg>
: public integral_constant<bool,
// Why is `static_cast` needed here?
noexcept(static_cast<_Tp>(declval<_Arg>()))> {};
如果发明的变量声明