getgroups: avoid compilation failure

[gnulib.git] / m4 / frexpl.m4

diff --git a/m4/frexpl.m4 b/m4/frexpl.m4
index 01cb1d9..c5da744 100644 (file)
--- a/m4/frexpl.m4
+++ b/m4/frexpl.m4
@@ -1,5 +1,5 @@
-# frexpl.m4 serial 6
-dnl Copyright (C) 2007 Free Software Foundation, Inc.
+# frexpl.m4 serial 9
+dnl Copyright (C) 2007-2009 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.
@@ -48,7 +48,7 @@ AC_DEFUN([gl_FUNC_FREXPL],
     gl_func_frexpl=no
   fi
   if test $gl_func_frexpl = yes; then
-    AC_DEFINE([HAVE_FREXPL], 1,
+    AC_DEFINE([HAVE_FREXPL], [1],
       [Define if the frexpl() function is available.])
     dnl Also check whether it's declared.
     dnl MacOS X 10.3 has frexpl() in libc but doesn't declare it in <math.h>.
@@ -84,7 +84,7 @@ AC_DEFUN([gl_FUNC_FREXPL_NO_LIBM],
     REPLACE_FREXPL=1
   fi
   if test $gl_func_frexpl_no_libm = yes; then
-    AC_DEFINE([HAVE_FREXPL_IN_LIBC], 1,
+    AC_DEFINE([HAVE_FREXPL_IN_LIBC], [1],
       [Define if the frexpl() function is available in libc.])
     dnl Also check whether it's declared.
     dnl MacOS X 10.3 has frexpl() in libc but doesn't declare it in <math.h>.
@@ -96,8 +96,9 @@ AC_DEFUN([gl_FUNC_FREXPL_NO_LIBM],
 ])
 
 dnl Test whether frexpl() works on finite numbers (this fails on
-dnl MacOS X 10.4/PowerPC, on AIX 5.1, and on BeOS) and also on infinite numbers
-dnl (this fails e.g. on IRIX 6.5 and mingw).
+dnl MacOS X 10.4/PowerPC, on AIX 5.1, and on BeOS), on denormalized numbers
+dnl (this fails on MacOS X 10.5/i386), and also on infinite numbers (this
+dnl fails e.g. on IRIX 6.5 and mingw).
 AC_DEFUN([gl_FUNC_FREXPL_WORKS],
 [
   AC_REQUIRE([AC_PROG_CC])
@@ -105,7 +106,13 @@ AC_DEFUN([gl_FUNC_FREXPL_WORKS],
   AC_CACHE_CHECK([whether frexpl works], [gl_cv_func_frexpl_works],
     [
       AC_TRY_RUN([
+#include <float.h>
 #include <math.h>
+/* Override the values of <float.h>, like done in float.in.h.  */
+#if defined __i386__ && (defined __BEOS__ || defined __OpenBSD__)
+# undef LDBL_MIN_EXP
+# define LDBL_MIN_EXP    (-16381)
+#endif
 extern long double frexpl (long double, int *);
 int main()
 {
@@ -144,6 +151,21 @@ int main()
           return 1;
       }
   }
+  /* Test on denormalized numbers.  */
+  {
+    int i;
+    for (i = 1, x = 1.0L; i >= LDBL_MIN_EXP; i--, x *= 0.5L)
+      ;
+    if (x > 0.0L)
+      {
+        int exp;
+        long double y = frexpl (x, &exp);
+        /* On machines with IEEE854 arithmetic: x = 1.68105e-4932,
+           exp = -16382, y = 0.5.  On MacOS X 10.5: exp = -16384, y = 0.5.  */
+        if (exp != LDBL_MIN_EXP - 1)
+          return 1;
+      }
+  }
   /* Test on infinite numbers.  */
   x = 1.0L / 0.0L;
   {