Re: [lmi] [lmi-commits] odd/gpt e293170 1/5: Add an equality operator

[Vadim Zeitlin]

On Tue, 27 Apr 2021 22:30:56 +0000 Greg Chicares <gchicares@sbcglobal.net> 
wrote:

GC> On 4/27/21 9:46 PM, Vadim Zeitlin wrote:
GC> > On Tue, 27 Apr 2021 21:26:23 +0000 Greg Chicares 
<gchicares@sbcglobal.net> wrote:
GC> [...]
GC> > GC> As I read SD-6, an implementation is free to define any of these
GC> > GC> macros to be zero, even if it doesn't support the corresponding
GC> > GC> feature.
GC> > 
GC> >  To be honest, I'm not sure if this is the correct reading, but my main
GC> > point is that in practice the only 3 existing C++20 implementations don't
GC> > do this and I consider it extremely unlikely that any implementation
GC> > appearing in the future would make a choice to be intentionally
GC> > incompatible with the existing ones in such a basic way.
GC> 
GC> Okay, in future I'll just test
GC>   #if defined __cpp_whatever

 Thanks, suggesting this was the only reason for my original reply, so I'm
glad to see that it was finally useful and not just a waste of your time
for once.

GC> Surely other people are doing that, too, so it will have become
GC> established practice that compiler vendors will avoid breaking.

 Yes. And a quick search for these macros shows that nobody actually
accepts unknown but strictly positive values. I.e. either people test for
just the definedness, or they explicitly check if it's less than the
required value (e.g. in __cpp_impl_three_way_comparison case, to given an
explicit #error if it's <= 201711).

GC> Before merging your std::filesystem work, I still have to deal
GC> with some small numerical regressions (with i686-w64-mingw32) that
GC> I hadn't expected.

 I'll do my best to be patient. Now that I've finally got this patch off my
back (I hope?), I can work on several other things that I had postponed
until it was done, so I do have things to do. The problem is that you risk
being submerged in patches if I do all of them, so maybe I'll concentrate
on the wx side of things for now, in order to make sure we can update it as
planned.

 Regards,
VZ

pgp8qV6hJCCwi.pgp
Description: PGP signature