On Wed, Nov 29, 2023 Lénárd Szolnoki via Std-Proposals wrote:
>
> The precondition for memcpy is trivially copyable *and* not potentially
> overlapping. The former doesn't imply the latter.
>
> https://godbolt.org/z/xhsqdoz3s


I've been playing around with this on GodBolt:

    https://godbolt.org/z/Ecd338Go8

The output of this program on Linux x86_64 GNU g++ 13.2.0 is:

    Address of b.a.i == 140727507144480
    Address of b.a.ch == 140727507144484
    Address of b.maybe_extra_byte == 140727507144485
    77
    0

So I am able to screw up the value of 'maybe_extra_byte' by memcpy'ing
over the A object that exists inside B. Is this what the committee
intended?

If this _is_ what the compiler intended, then should every C++
compiler issue a diagnostic whenever you pass the address of a
'no_unique_address' object to memcpy?