floor*-ieee, ceil*-ieee, trunc*-ieee, round*-ieee: More robust checks.

[gnulib.git] / m4 / roundf.m4

diff --git a/m4/roundf.m4 b/m4/roundf.m4
index 0ff9646..83dffd1 100644 (file)
--- a/m4/roundf.m4
+++ b/m4/roundf.m4
@@ -1,4 +1,4 @@
-# roundf.m4 serial 11
+# roundf.m4 serial 12
 dnl Copyright (C) 2007-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -66,10 +66,12 @@ int main()
 #include <math.h>
 ]gl_FLOAT_MINUS_ZERO_CODE[
 ]gl_FLOAT_SIGNBIT_CODE[
-int main()
+static float dummy (float f) { return 0; }
+int main (int argc, char *argv[])
 {
+  float (*my_roundf) (float) = argc ? roundf : dummy;
   /* Test whether roundf (-0.0f) is -0.0f.  */
-  if (signbitf (minus_zerof) && !signbitf (roundf (minus_zerof)))
+  if (signbitf (minus_zerof) && !signbitf (my_roundf (minus_zerof)))
     return 1;
   return 0;
 }