On 15 August 2016 at 12:53, Jonathan Wakely <[email protected]> wrote:
>> + template<typename>
>> + struct __is_in_place_impl : false_type
>> + { };
>> +
>> + template<typename _Tp>
>> + struct __is_in_place_impl<in_place_type_t<_Tp>> : true_type
> Indentation nit.
Will fix.
>
>> + { };
>> +
>> + template<typename _Tp>
>> + struct __is_in_place
>> + : public
>> __is_in_place_impl<std::remove_cv_t<std::remove_reference_t<_Tp>>>
>
>
> Any reason not to use decay_t here? In all the cases where decay is
> different to stripping references and cv-qualifiers the result will be
> false either way.
>
> I wouldn't have bothered with the std:: qualification either, but it's
> fine as it is.
The reason for not using decay and for the qualification is that the
trait is closely
related to its copy-paste origin, which is __is_optional. ;) I should
also add a test
for the case where in_place is attempted to pass through the
ValueType&& parameter,
aka a case where a type is not default-constructible but is
constructible from in_place,
and in_place-construction is used.
