Re: [hash2] Comments

From: Ivan Matek (libbooze_at_[hidden])
Date: 2024-12-07 00:23:49

On Sat, Dec 7, 2024 at 1:08 AM Andrey Semashev via Boost <
boost_at_[hidden]> wrote:

> On 12/7/24 01:42, Ivan Matek wrote:
> >
> >
> > On Fri, Dec 6, 2024 at 10:36 PM Andrey Semashev via Boost
> > <boost_at_[hidden] <mailto:boost_at_[hidden]>> wrote:
>
>
> As to the usage with the forced move, I don't think the added complexity
> is justified. If the goal is to make sure the hash value doesn't change
> upon successive calls to result() (to use the existing nomenclature)
>

Goal was to "encourage" users in 2 ways to call result() only once. First
way is that move signals that value is "tainted", second is that clang-tidy
can detect double moves sometimes.

>  But I don't see the benefit in introducing UB (potentially, to be caught
> by sanitizers - *if* one runs
> one) upon subsequent calls to result().
>

If you are referring to multiple calls to
get_digest(std::move(h));
There is no UB. Move is just a cast, we do not nuke the member when we
return it's result(), and clang-tidy checks are static(not runtime).

I understand it is verbose, but I can not think of anything better(unless
we just do nothing :( ).

>
>
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