Re: clar unit testing framework FTBFS on uclibc systems (wchar_t unsupported)

From: Jeff King <peff@peff.net>
Date: Oct 18, 2024, 04:51 UTC
Message-ID: <20241018045155.GC2408674@coredump.intra.peff.net>
In-Reply-To: <ZxGN9zzt55GcL4Qj@tapette.crustytoothpaste.net>

On Thu, Oct 17, 2024 at 10:21:43PM +0000, brian m. carlson wrote:

Show 16 quoted lines

> > We unconditionally include <wchar.h>, and your system does not seem to
> > have support for it built in. So why doesn't the `#error` trigger? It's
> > also not like this is a recent error, it has been added with 581deed72
> > (The obligatory forgotten files..., 2002-05-06).
> > 
> > We can do something like the below patch in clar, but I'd first like to
> > understand why your platform seems to be broken in such a way.
> 
> Yeah, this is definitely broken.  We require ISO C99, and according to
> the draft preceding the ratification[0], `wchar.h` and its contents are not
> optional.  The similar draft for C11 also doesn't appear to make these
> optional.
> 
> I think users of uclibc will need to compile it with full ISO C99
> support.  I expect that a wide variety of other software will be
> similarly broken without that.

Perhaps, but...don't the current releases of Git work just fine on such a wchar-less uclibc system now? We don't use wchar or include wchar.h ourselves, except on Windows or via compat/regex (though it is even conditional there). This is a new portability problem introduced by the clar test harness. And even there I doubt it is something we care about (it looks like it's for allowing "%ls" in assertions).

Our approach to portability has traditionally been a cost/benefit for individual features. Standards are a nice guideline, but the real world does not always follow them. Sometimes accommodating platforms that don't strictly follow the standard is cheap enough that it's worth doing.

I think more recent discussions have trended to looking at standards in a bit stronger way: giving minimum requirements and sticking to them. Certainly I'm sympathetic to that viewpoint, as it can reduce noise.

But IMHO this is a good example of where the flexibility of the first approach shines. We could accommodate this platform without any real cost (and indeed, we should be able to _drop_ some clar code).

-Peff