Eric Blake wrote:
> No, on cygwin, isnan is a macro in <math.h> that wraps the internal
> functions __isnan{,lf}, and the isnan entry point in cygwin1.dll exists
> only for backwards compatibility for multi-year-old apps that were
> compiled against cygwin prior to the POSIX compliance bug being fixed of
> providing isnan only as a macro.
My copy of cygwin <math.h> (dated 2006-01-20) still has
extern int isnan _PARAMS((double));
You simply have a newer copy of cygwin than me.
> And you still didn't catch my point that
> on cygwin, you don't need -lm to get isnan() to work
Since there are also AIX, OSF/1, HP-UX, the situation on cygwin has no
effect on m4/isnan.m4.
> Checking AC_CHECK_FUNC([isnan]) is
> wrong since POSIX does not guarantee that isnan is a function; instead,
> you must check whether including <math.h> and using isnan() will link
> correctly in the absence of -lm.
Oh, I see now what you mean. Thanks for insisting. I had based my
understanding of these functions on a manual page that lists isnanf(),
isnan() as a function, and isnanl(). Doing as you say.
Bruno
2007-02-24 Bruno Haible <[EMAIL PROTECTED]>
* lib/isnanl.h (isnanl): Define through isnan if isnan is a macro.
* m4/isnan.m4 (gl_FUNC_ISNAN_NO_LIBM): Don't check for isnan as a
function; instead check whether isnan with a double argument links.
* m4/isnanl.m4 (gl_FUNC_ISNANL_NO_LIBM): Don't check for isnanl as a
function; instead check whether isnan with a 'long double' argument
links.
Reported by Eric Blake <[EMAIL PROTECTED]>.
*** lib/isnan.h 24 Feb 2007 19:08:56 -0000 1.1
--- lib/isnan.h 25 Feb 2007 04:38:13 -0000
***************
*** 16,22 ****
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#if HAVE_ISNAN_IN_LIBC
! /* Get declaration of isnan. */
# include <math.h>
#else
/* Test whether X is a NaN. */
--- 16,22 ----
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#if HAVE_ISNAN_IN_LIBC
! /* Get declaration of isnan macro. */
# include <math.h>
#else
/* Test whether X is a NaN. */
*** lib/isnanl.h 24 Feb 2007 19:15:21 -0000 1.1
--- lib/isnanl.h 25 Feb 2007 04:38:13 -0000
***************
*** 16,23 ****
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#if HAVE_ISNANL_IN_LIBC
! /* Get declaration of isnanl. */
# include <math.h>
#else
/* Test whether X is a NaN. */
# undef isnanl
--- 16,27 ----
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#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
#else
/* Test whether X is a NaN. */
# undef isnanl
*** m4/isnan.m4 25 Feb 2007 01:57:58 -0000 1.2
--- m4/isnan.m4 25 Feb 2007 04:38:13 -0000
***************
*** 8,19 ****
AC_DEFUN([gl_FUNC_ISNAN_NO_LIBM],
[
! AC_CHECK_FUNC([isnan],
! [gl_cv_func_isnan_no_libm=yes],
! [gl_cv_func_isnan_no_libm=no])
if test $gl_cv_func_isnan_no_libm = yes; then
AC_DEFINE([HAVE_ISNAN_IN_LIBC], 1,
! [Define if the isnan() function is available in libc.])
else
AC_LIBOBJ([isnan])
gl_DOUBLE_EXPONENT_LOCATION
--- 8,25 ----
AC_DEFUN([gl_FUNC_ISNAN_NO_LIBM],
[
! AC_CACHE_CHECK([whether isnan(double) can be used without linking with
libm],
! [gl_cv_func_isnan_no_libm],
! [
! AC_TRY_LINK([#include <math.h>
! double x;],
! [return isnan (x);],
! [gl_cv_func_isnan_no_libm=yes],
! [gl_cv_func_isnan_no_libm=no])
! ])
if test $gl_cv_func_isnan_no_libm = yes; then
AC_DEFINE([HAVE_ISNAN_IN_LIBC], 1,
! [Define if the isnan(double) function is available in libc.])
else
AC_LIBOBJ([isnan])
gl_DOUBLE_EXPONENT_LOCATION
*** m4/isnanl.m4 24 Feb 2007 19:15:21 -0000 1.1
--- m4/isnanl.m4 25 Feb 2007 04:38:13 -0000
***************
*** 8,19 ****
[
AC_REQUIRE([gt_TYPE_LONGDOUBLE])
if test $gt_cv_c_long_double = yes; then
! AC_CHECK_FUNC([isnanl],
! [gl_cv_func_isnanl_no_libm=yes],
! [gl_cv_func_isnanl_no_libm=no])
if test $gl_cv_func_isnanl_no_libm = yes; then
AC_DEFINE([HAVE_ISNANL_IN_LIBC], 1,
! [Define if the isnanl() function is available in libc.])
else
AC_LIBOBJ([isnanl])
gl_LONG_DOUBLE_EXPONENT_LOCATION
--- 8,29 ----
[
AC_REQUIRE([gt_TYPE_LONGDOUBLE])
if test $gt_cv_c_long_double = yes; then
! AC_CACHE_CHECK([whether isnan(long double) can be used without linking
with libm],
! [gl_cv_func_isnanl_no_libm],
! [
! AC_TRY_LINK([#include <math.h>
! #ifdef isnan
! # undef isnanl
! # define isnanl(x) isnan ((long double)(x))
! #endif
! long double x;],
! [return isnanl (x);],
! [gl_cv_func_isnanl_no_libm=yes],
! [gl_cv_func_isnanl_no_libm=no])
! ])
if test $gl_cv_func_isnanl_no_libm = yes; then
AC_DEFINE([HAVE_ISNANL_IN_LIBC], 1,
! [Define if the isnan(long double) function is available in libc.])
else
AC_LIBOBJ([isnanl])
gl_LONG_DOUBLE_EXPONENT_LOCATION
