[C++ PATCH RFC] PR c++/80265 - constexpr __builtin_mem*.

[Jason Merrill]

On Mon, Jan 13, 2020 at 6:11 AM Jonathan Wakely <jwakely@redhat.com> wrote:

> On 11/01/20 00:03 -0500, Jason Merrill wrote:
> >The library has already worked around this issue, but I was curious about
> >why it wasn't working.  The answer: because we were passing &var to fold,
> >which doesn't know about the constexpr values hash table.  Fixed by
> passing
> >&"str" instead.
> >
> >Tested x86_64-pc-linux-gnu.  Does this seem useful even though it isn't
> >necessary anymore?
>
> I'd still like to be able to use memcpy and memmove in constexpr
> evaluation. We've added our own "std::__memmove" for use at compile
> time, but it doesn't really have the same semantics. We could fix
> that, but it would be better to just use the real thing.
>

Ah, supporting memcpy/memmove would be more work than the cmp/chr
functions, I'd have to reimplement them entirely in constexpr.c.

Jason