On Thu, Nov 30, 2023 at 4:33 PM Frederick Virchanza Gotham via
Std-Proposals <std-proposals_at_[hidden]> wrote:

> On Thu, Nov 30, 2023 at 8:36 PM Arthur O'Dwyer wrote:
> >
> > This is the `__datasizeof` builtin. In chronological order:
> > https://orodu.net/2023/01/15/trivially-relocatable.html (Ctrl+F
> data_size_of)
> >
> https://quuxplusone.github.io/blog/2023/02/24/trivial-swap-x-prize/#if-stdswap-cant-memcpy-then-how-do-we-trivially-swap
> >
> https://clang.llvm.org/docs/LanguageExtensions.html#implementation-defined-keywords
>
> Okay then so we need __datasizeof in C++26, right?
>

No. Let's see it get into more than one compiler, first; and also get some
usage experience in practice.
So far, as far as practical uses are concerned, I'm only aware of the
std::copy/std::move/std::swap_ranges family; and the current debacle with
std::expected <https://github.com/llvm/llvm-project/issues/68552> in
libc++. And the latter shouldn't count as we never should have got into
that situation to begin with.

–Arthur