I don't think it's UB since the underlying memory is not read-only.
Arthur's solution can be improved using hints but I think that would still
require checking node(s) around the hint to verify that position is correct.
Btw, boost::container::set works in the way you need.

On Mon, May 22, 2023 at 9:32 AM Thiago Macieira via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> On Sunday, 21 May 2023 14:09:30 PDT Frederick Virchanza Gotham via Std-
> Proposals wrote:
> > I wrote the following code today; I have a struct for storing an IP
> > address as well as two booleans (one for a FTP server and one for a
> > Samba file server):
> >
> > struct IPFileShare {
> > std::uint32_t ip;
>
> <rant>IP addresses aren't 32-bit and haven't been since the late 1990s. Is
> your code stuck in the 80s?</rant>
>
> Let's not ever write or even suggest code that fails to work with IPv6.
>
> > I think strictly speaking, the Standard says that this is undefined
> > behaviour. How about we change the Standard to say that this
> > const_cast is allowed so long as it has no effect on the sorting?
>
> In addition to what Arthur said, std::set is not just about sorting, it's
> about identity. The fact that your type seems to carry extra information
> that
> is not part of the identity does not mean it's the case for all other
> types.
>
> Let's not break the requirements without compelling reason. I didn't see a
> compelling reason why it has to be this way. What other alternatives have
> you
> explored and what were their drawbacks?
>
> --
> Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
> Software Architect - Intel DCAI Cloud Engineering
>
>
>
> --
> Std-Proposals mailing list
> Std-Proposals_at_[hidden]
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>

-- 
Regards,
Oleksandr Koval.