On Wed, 21 May 2025 at 16:29, Frederick Virchanza Gotham via
Std-Proposals <std-proposals_at_[hidden]> wrote:
>
> On Wed, May 21, 2025 at 11:36 AM Jonathan Wakely wrote:
> >
> > > typedef std::optional<int> T;
> > > alignas(T) char unsigned storage[sizeof(T)];
> > > T &r = *static_cast<T*>(static_cast<void*>(&storage));
> > > if ( AllInUniversal() ) std::construct_at(&r, 42 );
> > > /****************/ else std::construct_at(&r, std::nullopt);
> >
> > wat
> >
> > Why would you want it to be turned into that, rather than what you wrote above?
> >
> > std::optional<int> r = cond ? std::optional<int>(42) :
> > std::optional<int>(std::nullopt);
> >
> > This already avoids any copy due to guaranteed elision. Your version
> > using a byte array and construct_at is just unnecessarily complex.
>
>
>
> Obviously my code is pretty horrible -- I was trying to give an idea
> of what would happen "under the hood", so to speak. I was trying to
> show how the ternary operator might, under the hood, be turned into an
> "if - else" resulting in two separate statements to initialise the
> "optional" variable.


Yes, but you said something like "you can do X, but were you hoping
for Y instead?" and my point is that X == Y already. There's no
"instead" because it's already equivalent to that.

So spelling out Y in great detail when it's exactly what X does anyway
just seems like unnecessary complexity and obfuscation.