wt., 9 gru 2025 o 16:21 Bjorn Reese via Std-Proposals
<std-proposals_at_[hidden]> napisał(a):
>
> On 12/9/25 09:07, Shivam Kunwar via Std-Proposals wrote:
>
> > The Problem :
> >
> > Cryptographic code needs to perform conditional selection without
> > leaking timing information. The standard pattern looks like this
> >
> > // Intended to be constant-time
> > uint64_t mask = -(uint64_t)(!!cond);
> > result = (a & mask) | (b & ~mask);
>
> Notice that SIMD works this way.
>
> > template<class T>
> > constexpr T select_explicit(bool test, T a, T b) noexcept;
>
> It may be beneficial to explore the direction taken in the std::simd
> proposal, which has an exposition-only conditional function because
> the conditional operator cannot be overloaded:
>
> https://eel.is/c%2B%2Bdraft/simd.nonmembers#simd.cond
>
> There is also a proposal to make the conditional operator overloadable:
>
> https://wg21.link/P0917
>

Did we have already foot gun when someone overload `||`?
Like `T{} || p->foo()` will crash depending if `T` overloaded it or not.

> This does not, however, solve the problem of optimizers favouring
> conditional instructions.
>
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