Re: float.h: Do not define INFINITY for C2x when infinities not supported

[Richard Biener <richard.guenther@gmail.com>]

On Thu, Sep 15, 2022 at 1:02 AM Joseph Myers <joseph@codesourcery.com> wrote:
>
> C2x has changed the rules for defining INFINITY in <float.h> so it is
> no longer defined when float does not support infinities, instead of
> being defined to an expression that overflows at translation time.
> Thus, make the definition conditional on __FLT_HAS_INFINITY__ (this is
> already inside a C2x-conditional part of <float.h>, because previous C
> standard versions only had this macro in <math.h>).
>
> Bootstrapped with no regressions for x86_64-pc-linux-gnu.  Also did a
> spot test of the case of no infinities supported by building cc1 for
> vax-netbsdelf and testing compiling the new c2x-float-11.c test with
> it.

Ok

> gcc/
>         * ginclude/float.h (INFINITY): Define only if
>         [__FLT_HAS_INFINITY__].
>
> gcc/testsuite/
>         * gcc.dg/c2x-float-2.c: Require inff effective-target.
>         * gcc.dg/c2x-float-11.c: New test.
>
> diff --git a/gcc/ginclude/float.h b/gcc/ginclude/float.h
> index 9d368c4afa5..afe4a712878 100644
> --- a/gcc/ginclude/float.h
> +++ b/gcc/ginclude/float.h
> @@ -257,9 +257,11 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
>  #define DBL_IS_IEC_60559       __DBL_IS_IEC_60559__
>  #define LDBL_IS_IEC_60559      __LDBL_IS_IEC_60559__
>
> -/* Infinity in type float, or overflow if infinity not supported.  */
> +/* Infinity in type float; not defined if infinity not supported.  */
> +#if __FLT_HAS_INFINITY__
>  #undef INFINITY
>  #define INFINITY       (__builtin_inff ())
> +#endif
>
>  /* Quiet NaN, if supported for float.  */
>  #if __FLT_HAS_QUIET_NAN__
> diff --git a/gcc/testsuite/gcc.dg/c2x-float-11.c b/gcc/testsuite/gcc.dg/c2x-float-11.c
> new file mode 100644
> index 00000000000..0e2f3c0c97a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/c2x-float-11.c
> @@ -0,0 +1,9 @@
> +/* Test INFINITY macro.  Test when infinities not supported.  */
> +/* { dg-do compile { target { ! inff } } } */
> +/* { dg-options "-std=c2x" } */
> +
> +#include <float.h>
> +
> +#ifdef INFINITY
> +#error "INFINITY defined"
> +#endif
> diff --git a/gcc/testsuite/gcc.dg/c2x-float-2.c b/gcc/testsuite/gcc.dg/c2x-float-2.c
> index 4f669fd39bc..61a77f6f2db 100644
> --- a/gcc/testsuite/gcc.dg/c2x-float-2.c
> +++ b/gcc/testsuite/gcc.dg/c2x-float-2.c
> @@ -1,8 +1,8 @@
> -/* Test INFINITY macro.  Generic test even if infinities not
> -   supported.  */
> +/* Test INFINITY macro.  Generic test.  */
>  /* { dg-do run } */
>  /* { dg-options "-std=c2x -w" } */
>  /* { dg-add-options ieee } */
> +/* { dg-require-effective-target inff } */
>
>  #include <float.h>
>
>
> --
> Joseph S. Myers
> joseph@codesourcery.com