Re: test-float fails on powerpc

[Bruno Haible]

Hello Santiago,

> I implicitly enabled gnulib tests in the Debian diffutils package
> (by switching debian/rules to debhelper) and now the package fails to
> build from source on the powerpc architecture because test-float fails:
> 
> ./test-float 
> test-float.c:333: assertion failed
> Aborted
> 
> This is the relevant code:
> 
>  /* Check the value of LDBL_MAX.  */
>   {
>     volatile long double m = LDBL_MAX;
>     int n;
> 
>     ASSERT (m + m > m);
>     for (n = 0; n <= 2 * LDBL_MANT_DIG; n++)
>       {
>         volatile long double pow2_n = pow2l (n); /* 2^n */
>         volatile long double x = m + (m / pow2_n);
>         if (x > m)
>           ASSERT (x + x == x);   /* <==== This is the line which fails */
>         else
>           ASSERT (!(x + x == x));
>       }
>   }

This failure location indicates a severe problem with <float.h>

> In the meantime, I will disable this test in the Debian package.

This is not useful, because <float.h> on Linux/PowerPC *is* broken.
It would be better for you to incorporate the fix. Either by invoking
"gnulib-tool --update", or by taking just the bug's workaround from
the gnulib repository:
http://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=commitdiff;h=c65d65a81e9d66960ae7ce5abe5069d5b7338ed2

Bruno