[Cython] Cygwin: Handling missing C99 long double functions

[Dima Pasechnik]

Hi,
certainly we did something with Sage on cygwin to work around these...
Just in case,
Dima

On Tue, Apr 26, 2016 at 3:58 PM, Erik Bray <erik.m.bray at gmail.com> wrote:
> Hi again,
>
> Sorry if I'm spamming the list too much, but I've encountered another
> pretty serious and unfortunate issue with Cython on Cygwin.
>
> The problem now is that many of libm long double functions like sqrtl,
> tanl, etc. are missing on Cygwin (missing from newlib to be specific).
> I think this is a previously known issue, but nothing's ever really
> been done about it.  Well, to be clear, sometimes they're present, but
> only when sizeof(double) == sizeof(long double).  However on 64-bit
> Cygwin sizeof(long double) == 16, so the functions are simply not
> defined.
>
> This seems to be due to lack of interest / effort:
> https://www.cygwin.com/ml/cygwin/2011-04/msg00231.html  That post is 5
> years old, but I can't find any evidence that this has changed.
>
> There are quite a few tests in Cygwin's test suite that test long
> double support.  I guess what I'm asking is what would be the best
> thing to do about it.
>
> I could just skip those tests on Cygwin, though I'm not sure the best
> way to go about skipping an entire test for a given platform.
>
> More generally though, outside the context of testing, this means
> Cygwin will sometimes generate code that cannot be compiled on this
> platform, and a question arises as to what to do about that.  I have
> some thoughts, but am not sure if it's worth discussing any further or
> not.
>
> Thanks,
> Erik
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