Re: gdal 3.9.0, C++17, charconv, gcc7

[Greg Troxel <gdt%lexort.com@localhost>]

nia <nia%NetBSD.org@localhost> writes:

> On Sat, Jun 08, 2024 at 06:37:59AM -0400, Greg Troxel wrote:
>> Also, I think we as a larger community have reached the point where
>> using gcc7 as a base compiler is no longer reasonable.  It's probably
>> only because of NetBSD's super-long release cycle (and LTS
>> distributions) that we are even having this discussion.  That to me
>> argues for not weighting "want to use a compiler that is too old to be
>> reliable" very much.
>
> If you don't care about supporting too-old distributions then
> why are you proposing changes to USE_CXX_FEATURES? That's its only
> purpose.

I am not following.

gcc7 is very old.  Some systems (NetBSD 9) use it as the base compiler.
For programs written in a language variant that gcc7 doesn't support,
such as C++17, a newer compiler is needed.  (And yes, some C++17
programs can be build by gcc7.)  I think everybody agrees on that.

The question then is how pkgsrc should deal with NetBSD 9.  I think it's
reasonable to build gcc10 and use it, and I think everybody else does
too.  The only real question is exactly when.  My view is that gcc does
not support C++17 and that there is little value in trying to avoid
gcc10.  I also think there is value in clean semantics where things mean
what they say.  Others, and I think you are in this category, prefer to
avoid gcc10 in some cases, weighting that higher than clean semantics.

My concern is that there is no path from "this program declares that it
needs this language spec" to "declare that in the makefile and get sound
behavior".