There is a whole series of things by Pal Balog dealing with layout too.

On Thu, Feb 27, 2020, 17:01 Arvid Norberg via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> On Thu, Feb 27, 2020 at 5:50 PM Brian Bi via Std-Proposals <
> std-proposals_at_[hidden]> wrote:
>
>> On Thu, Feb 27, 2020 at 10:37 AM Ryan Nicholl via Std-Proposals <
>> std-proposals_at_[hidden]> wrote:
>> [...]
>> I think it's better to have the order of construction and destruction go
>> according to the declaration order, and add some new feature to control the
>> memory layout, rather than the reverse.
>>
>
> Rene Rivera wrote a paper for this that he presented in SG14.
>
>
> https://raw.githack.com/grafikrobot/papers/master/wg21/member_layout/member_layout_D1605R0.html
>
> --
> Arvid Norberg
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