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

[Jonathan Wakely]

On 13/01/20 12:53 -0500, Jason Merrill wrote:
>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.

Ah, OK, nevermind then. We'll reimplement just what we need in the
library.