Re: USE_LANGUAGES and wrappers

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

Joerg Sonnenberger <joerg%bec.de@localhost> writes:

> On Wed, Jul 19, 2023 at 10:50:14AM -0400, Greg Troxel wrote:
>> Joerg Sonnenberger <joerg%bec.de@localhost> writes:
>> 
>> > On Wed, Jul 19, 2023 at 02:13:53PM +0000, nia wrote:
>> >> "cwrappers should always default to oldest version of the C/C++ standard
>> >> unless -std=XX is given" is not quite as trivial but should also be doable.
>> >
>> > This is going to seriously annoy any one using a compiler defaulting to
>> > a newer language mode when it also introduces any ABI differences. So
>> > when given a choice between pissing off users on modern system and some
>> > fallout on outdated systems, I'm strongly inclined to go with the
>> > former.
>> 
>> Do people really think it's ok for a compiler to change ABI for varying
>> --std arguments?
>
> It's OK for a *library* to change the ABI based on the standard flags.
> After all, how else are they supposed to be able to use and/or expose
> them.

That's an answer to a question I didn't ask :-), but it's interesting
and relevant.  It would seem then that a package containing a library
has to declare the c++ language variants it supports, explain in the
README how to build the library for varying language variants, and to
explain how one should deal with needing multiple versions.

Can you point to any such libraries in pkgsrc, explain the variation
issues, and how we handle that now?


(Answers to my four questions from anybody else are of course welcome.)