perhaps gnu.ver inconsistency

[Jonathan Wakely]

On 23 March 2014 09:29, Denis Excoffier wrote:
> Hello,
>
> Could someone please explain why powl is listed in libstdc++-v3/config/abi/pre/gnu.ver although fabsl is not?

Probably because at some point it was needed.
On my GNU/Linux system the library doesn't export fabsl or powl.

> I suppose this is the reason why my home-made libstdc++.dll.a (on cygwin) does not know fabsl:
>
> % nm -go libstdc++.dll.a | grep fabsl
> % nm -go libstdc++.dll.a | grep powl
> libstdc++.dll.a:d003549.o:00000000 I __imp__powl
> libstdc++.dll.a:d003549.o:00000000 T _powl
> %

There could be other reasons, the library only defines fabsl conditionally:

#ifndef _GLIBCXX_HAVE_FABSL
  long double
  fabsl(long double x)
  {
    return fabs((double) x);
  }
#endif

Is that macro defined (after including a C++ library header, such as
<cmath>) on Cygwin?