- AC_TRY_RUN([
-#include <float.h>
-#include <stddef.h>
-#include <stdio.h>
-#include <string.h>
-#define NWORDS \
- ((sizeof (float) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
-typedef union { float value; unsigned int word[NWORDS]; } memory_float;
-static unsigned int ored_words[NWORDS];
-static unsigned int anded_words[NWORDS];
-static void add_to_ored_words (float x)
+ save_LIBS="$LIBS"
+ LIBS="$LIBS -lm"
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <math.h>
+ #if __GNUC__ >= 4
+ # undef isnanf
+ # define isnanf(x) __builtin_isnanf ((float)(x))
+ #elif defined isnan
+ # undef isnanf
+ # define isnanf(x) isnan ((float)(x))
+ #endif
+ float x;]],
+ [[return isnanf (x);]])],
+ [gl_cv_func_isnanf_in_libm=yes],
+ [gl_cv_func_isnanf_in_libm=no])
+ LIBS="$save_LIBS"
+ ])
+])
+
+dnl Test whether isnanf() rejects Infinity (this fails on Solaris 2.5.1),
+dnl recognizes a NaN (this fails on IRIX 6.5 with cc), and recognizes a NaN
+dnl with in-memory representation 0x7fbfffff (this fails on IRIX 6.5).
+AC_DEFUN([gl_ISNANF_WORKS],
+[
+ AC_REQUIRE([AC_PROG_CC])
+ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+ AC_REQUIRE([gl_FLOAT_EXPONENT_LOCATION])
+ AC_CACHE_CHECK([whether isnan(float) works], [gl_cv_func_isnanf_works],
+ [
+ AC_RUN_IFELSE(
+ [AC_LANG_SOURCE([[
+#include <math.h>
+#if __GNUC__ >= 4
+# undef isnanf
+# define isnanf(x) __builtin_isnanf ((float)(x))
+#elif defined isnan
+# undef isnanf
+# define isnanf(x) isnan ((float)(x))
+#endif
+/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0. */
+#ifdef __DECC
+static float
+NaN ()