+
+dnl Test whether log10l() works.
+dnl On OSF/1 5.1, log10l(-0.0L) is NaN.
+dnl On IRIX 6.5, log10l(-0.0L) is an unnormalized negative infinity
+dnl 0xFFF00000000000007FF0000000000000, should be
+dnl 0xFFF00000000000000000000000000000.
+dnl On AIX 5.1, log10l(-0.0L) is finite if it's not the first log10l call
+dnl in the program.
+AC_DEFUN([gl_FUNC_LOG10L_WORKS],
+[
+ AC_REQUIRE([AC_PROG_CC])
+ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+ AC_CACHE_CHECK([whether log10l works], [gl_cv_func_log10l_works],
+ [
+ AC_RUN_IFELSE(
+ [AC_LANG_SOURCE([[
+#include <math.h>
+#ifndef log10l /* for AIX */
+extern
+#ifdef __cplusplus
+"C"
+#endif
+long double log10l (long double);
+#endif
+volatile long double x;
+long double y;
+int main ()
+{
+ /* Dummy call, to trigger the AIX 5.1 bug. */
+ x = 0.6L;
+ y = log10l (x);
+ /* This test fails on AIX 5.1, IRIX 6.5, OSF/1 5.1. */
+ x = -0.0L;
+ y = log10l (x);
+ if (!(y + y == y))
+ return 1;
+ return 0;
+}
+]])],
+ [gl_cv_func_log10l_works=yes],
+ [gl_cv_func_log10l_works=no],
+ [case "$host_os" in
+ aix* | irix* | osf*) gl_cv_func_log10l_works="guessing no";;
+ *) gl_cv_func_log10l_works="guessing yes";;
+ esac
+ ])
+ ])
+])