On Fri, 7 Aug 2020 at 21:21, Walt Karas via Std-Proposals
<std-proposals_at_[hidden]> wrote:
>
> On Friday, August 7, 2020, 12:57:08 PM CDT, Ville Voutilainen <ville.voutilainen_at_[hidden]> wrote:
> On Fri, 7 Aug 2020 at 20:47, Walt Karas via Std-Proposals
> <std-proposals_at_[hidden]> wrote:
> > You can't do a destroy+placement-new if the placement-new can throw.
> >
> > WK: OK, also good point. If the constructor can throw, then conceptually the default assign can be like this: https://godbolt.org/z/jvdf53
>
> That approach doesn't work for anything non-trivial, and requires
> C++20 implicit object creation otherwise.
>
> WK: Hmm can you give quick example of a class for which this would not work? Or can you give a smaller reference than two long (and expensive) books?

struct X
{
    std::string str;
};

This type can *NOT* be memcpyed, and restoring it from raw bytes is
equally non-doable.

struct Y
{
// data members omitted, they don't really matter
    Y(); // non-trivial
    Y(const Y&); // non-trivial
};

This type can *NOT* be memcpyed, and restoring it from raw bytes is
equally non-doable.