Re: c++20: require gcc12?

[Martin Husemann <martin%duskware.de@localhost>]

On Tue, Feb 11, 2025 at 02:27:05PM -0500, Greg Troxel wrote:
> Martin Husemann <martin%duskware.de@localhost> writes:
> 
> > Since this is the canonical way to have autoconf test for C++20 support,
> > I guess we really need to enforce a newer gcc.
> 
> I think it's really obvious that if gcc says you need 12 that we need to
> code 12.  I don't understand why there are any objections to doing
> that....

Because the predicate "c++20 support" is not very usefull.
You could read it as "you can't use clang at all" for example.

Gcc only has a single box in their C++20 support matrix marked as gcc 12,
everything else has been available longer.

But practical speaking: since AC_CXX_COMPILE_STDXX([20]....) will fail
on gcc 10 as we found out, it is pretty clear that we need something > 10,
even if that is not really required for most software out there -
only for lazyness of configure.ac authors.

Martin