Paul Eggert wrote:
> I ran into this problem when compiling coreutils 6.10 on Solaris 8
> (sparc) with GCC 4.2.2:
>
> frexp.c: In function 'rpl_frexpl':
> frexp.c:63: warning: implicit declaration of function 'isnanl'
> vasnprintf.c: In function 'is_infinitel':
> vasnprintf.c:252: warning: implicit declaration of function 'isnanl'
>
> Here, the problem is that isnanl is defined by libm, but it's not
> declared anywhere in /usr/include.
If that was the problem, one would also see the warning when gcc-3.x is
used. And I can see with "nm" that libm on Solaris 8 does not have 'isnanl'.
The problem is that GCC knows about isnanl as a built-in function. It
is compiled like __builtin_isnanl (supported by GCC >= 4.0), but gives a
warning.
> Here's a patch:
>
> 2008-01-24 Paul Eggert <[EMAIL PROTECTED]>
>
> * m4/isnanl.m4: Check that isnanl is declared, when it's used.
> (gl_HAVE_ISNANL_NO_LIBM, gl_HAVE_ISNANL_IN_LIBM): Check that
> isnanl is declared, if we are not going to override it anyway.
> This suppresses a warning when compiling coreutils 6.10 with GCC
> 4.2.2 on Solaris 8. In that combination, no include file defines
> isnanl, but it's in libm, and GCC issues a warning when compiling.
Although your patch is correct, I prefer not to use it: It has the effect
to reject GCC's built-in. Instead I find it better to use this built-in (on
those platforms where it works), since that will save a function call.
GCC's built-in does not pass our tests on x86, x86_64, ia64. But the libc
function does not do either. So it's acceptable to prefer the GCC built-in
to the libc implementation always.
Committed this:
2008-01-26 Bruno Haible <[EMAIL PROTECTED]>
* m4/isnanl.m4 (gl_HAVE_ISNANL_NO_LIBM, gl_HAVE_ISNANL_IN_LIBM,
gl_FUNC_ISNANL_WORKS): Test the GCC >= 4.0 built-in.
* lib/isnanl.h (isnanl): Use the GCC >= 4.0 built-in.
* lib/isnanl-nolibm.h (isnanl): Likewise.
Reported by Paul Eggert <[EMAIL PROTECTED]>.
*** lib/isnanl-nolibm.h.orig 2008-01-26 15:41:57.000000000 +0100
--- lib/isnanl-nolibm.h 2008-01-26 15:39:22.000000000 +0100
***************
*** 1,5 ****
/* Test for NaN that does not need libm.
! Copyright (C) 2007 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
--- 1,5 ----
/* Test for NaN that does not need libm.
! Copyright (C) 2007-2008 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
***************
*** 17,23 ****
#if HAVE_ISNANL_IN_LIBC
/* Get declaration of isnan macro or (older) isnanl function. */
# include <math.h>
! # ifdef isnan
# undef isnanl
# define isnanl(x) isnan ((long double)(x))
# endif
--- 17,27 ----
#if HAVE_ISNANL_IN_LIBC
/* Get declaration of isnan macro or (older) isnanl function. */
# include <math.h>
! # if __GNUC__ >= 4
! /* GCC 4.0 and newer provides three built-ins for isnan. */
! # undef isnanl
! # define isnanl(x) __builtin_isnanl ((long double)(x))
! # elif defined isnan
# undef isnanl
# define isnanl(x) isnan ((long double)(x))
# endif
*** lib/isnanl.h.orig 2008-01-26 15:41:57.000000000 +0100
--- lib/isnanl.h 2008-01-26 15:39:22.000000000 +0100
***************
*** 1,5 ****
/* Test for NaN.
! Copyright (C) 2007 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
--- 1,5 ----
/* Test for NaN.
! Copyright (C) 2007-2008 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
***************
*** 17,23 ****
#if HAVE_ISNANL
/* Get declaration of isnan macro or (older) isnanl function. */
# include <math.h>
! # ifdef isnan
# undef isnanl
# define isnanl(x) isnan ((long double)(x))
# endif
--- 17,27 ----
#if HAVE_ISNANL
/* Get declaration of isnan macro or (older) isnanl function. */
# include <math.h>
! # if __GNUC__ >= 4
! /* GCC 4.0 and newer provides three built-ins for isnan. */
! # undef isnanl
! # define isnanl(x) __builtin_isnanl ((long double)(x))
! # elif defined isnan
# undef isnanl
# define isnanl(x) isnan ((long double)(x))
# endif
*** m4/isnanl.m4.orig 2008-01-26 15:41:57.000000000 +0100
--- m4/isnanl.m4 2008-01-26 15:39:22.000000000 +0100
***************
*** 1,5 ****
! # isnanl.m4 serial 5
! dnl Copyright (C) 2007 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
--- 1,5 ----
! # isnanl.m4 serial 6
! dnl Copyright (C) 2007-2008 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
***************
*** 64,70 ****
[gl_cv_func_isnanl_no_libm],
[
AC_TRY_LINK([#include <math.h>
! #ifdef isnan
# undef isnanl
# define isnanl(x) isnan ((long double)(x))
#endif
--- 64,73 ----
[gl_cv_func_isnanl_no_libm],
[
AC_TRY_LINK([#include <math.h>
! #if __GNUC__ >= 4
! # undef isnanl
! # define isnanl(x) __builtin_isnanl ((long double)(x))
! #elif defined isnan
# undef isnanl
# define isnanl(x) isnan ((long double)(x))
#endif
***************
*** 84,90 ****
save_LIBS="$LIBS"
LIBS="$LIBS -lm"
AC_TRY_LINK([#include <math.h>
! #ifdef isnan
# undef isnanl
# define isnanl(x) isnan ((long double)(x))
#endif
--- 87,96 ----
save_LIBS="$LIBS"
LIBS="$LIBS -lm"
AC_TRY_LINK([#include <math.h>
! #if __GNUC__ >= 4
! # undef isnanl
! # define isnanl(x) __builtin_isnanl ((long double)(x))
! #elif defined isnan
# undef isnanl
# define isnanl(x) isnan ((long double)(x))
#endif
***************
*** 98,103 ****
--- 104,112 ----
dnl Test whether isnanl() recognizes all numbers which are neither finite nor
dnl infinite. This test fails e.g. on NetBSD/i386 and on glibc/ia64.
+ dnl Also, the GCC >= 4.0 built-in __builtin_isnanl does not pass the tests
+ dnl - for pseudo-denormals on i686 and x86_64,
+ dnl - for pseudo-zeroes, unnormalized numbers, and pseudo-denormals on ia64.
AC_DEFUN([gl_FUNC_ISNANL_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
***************
*** 109,115 ****
#include <float.h>
#include <limits.h>
#include <math.h>
! #ifdef isnan
# undef isnanl
# define isnanl(x) isnan ((long double)(x))
#endif
--- 118,127 ----
#include <float.h>
#include <limits.h>
#include <math.h>
! #if __GNUC__ >= 4
! # undef isnanl
! # define isnanl(x) __builtin_isnanl ((long double)(x))
! #elif defined isnan
# undef isnanl
# define isnanl(x) isnan ((long double)(x))
#endif
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