On 03/04/19 23:39 +0300, Ville Voutilainen wrote:
On Wed, 3 Apr 2019 at 23:32, Antony Polukhin <antosh...@gmail.com> wrote:
Looks good. Covers most of the use cases.
Please consider adding filesystem::path, pair, tuple, string_view?, error_code,
list, deque (myabe all the other containers), optional, variant itself (for
cases when variant holds another variant).
It would be very useful for the _Never_valueless_alt to return true for
aggregates that hold only never valueles types. Not sure that there is a
compiler builtin for getting all the aggregates types, but it could be
implemented via metaprogramming.
What metaprogram is capable of that?
I think it would need a compiler builtin like __bases and
__direct_bases, which we don't have (and couldn't use unless it was
already implemented in every compiler that uses libstdc++).
When is the ABI freeze for the C++17 additions?
This approach concerns me; it's a "get it right at the first chance
and then never change it", which is.. ..awkward. But I don't know
whether there's any
way around that.
To some extent that's the case every time we declare something
non-experimental. There are things I'd change about
std::__cxx11::string if I was doing that again, but we're stuck with
what we have.
At least for these never-valueless variants it's just a QoI
optimization, and if we don't make it work for every possible type it
doesn't matter much.
