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On Feb 2, 2017, at 5:27 AM, Marc Mutz <marc.mutz@kdab.com> wrote:
>=20
> Hi,
>=20
> I don't know the state of the default-swap proposal, but this here seems
> orthogonal, anyway:
>=20
> The following is intentionally kept very vague:
>=20
> I was wondering whether std::swap could not prefer to call a member-swap =
where
> it exists, and only otherwise perform the default 3-move-assignment that =
it
> has since C++11.
>=20
> A nice benefit of this would be that all the std::swap
> specialisations/overloads for (most) containers would go away, because th=
ey
> provide member-swap functions already.
>=20
> This would also mitigate the source-incompatibility described in this thr=
ead,
> as users could add member-swaps to their non-movable/non-copyable classes=
..

I=E2=80=99ve seen code in the wild where member swap calls std::swap using =
*this as one of the arguments.  So if we do this, we will silently turn a n=
on-zero amount of code into infinite recursion.

Howard

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