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])
+ 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() function is available in libc.])
+ [Define if the isnan(double) function is available in libc.])
else
AC_LIBOBJ([isnan])
gl_DOUBLE_EXPONENT_LOCATION