[v3] plus<void>

[Jonathan Wakely]

On 25 September 2013 06:41, Marc Glisse wrote:
> On Wed, 25 Sep 2013, Jonathan Wakely wrote:
>
>> I've had this sitting in my tree waiting to do something with,
>
>
> I did ask last week if someone had done it already...

Sorry :-\

>
>> I'm about to go to sleep so didn't check if the test covers anything yours
>> doesn't.
>
>
> In the test you have basic cover for all functors, and I cover only 2 cases
> (more specifically though, since I look at the return type cv-qual).
>
> In my patch, I added constexpr and noexcept, I couldn't see any reason not
> to for such basic utilities. Yes, I did read the wiki and noticed the vote
> yesterday about constexpr, but imho that's wrong.
>
>
>> It looks like your patch adds the default template argument even in
>> C++98 mode, I avoided that by putting forward declarations at the top
>> of the file, in a #if block.
>
>
> This only lets me write:
> std::plus<> *p;
> in C++98 mode (std::plus<> p; gives an error), doesn't seem that bad.
>
> And I also add the void specializations in C++11 mode, as an extension.
>
> Well, let's forget my patch and go with yours, though at least adding
> noexcept seems like a good idea.

Yes, noexcept is a good idea.

> (too bad we don't have noexcept(auto) here)
> (too bad we can't use decltype(auto) for the return type, as that would
> disable sfinae, it is a bad sign when the standard turns its nose up at its
> own dog food...)

Yeah, I think the idea is that concepts will make SFINAE a thing of
the past, but we're not there yet.