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

[gnulib.git] / m4 / floorf.m4

diff --git a/m4/floorf.m4 b/m4/floorf.m4
index d426569..aa76f8c 100644 (file)
--- a/m4/floorf.m4
+++ b/m4/floorf.m4
@@ -1,4 +1,4 @@
-# floorf.m4 serial 9
+# floorf.m4 serial 10
 dnl Copyright (C) 2007, 2009-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -35,10 +35,12 @@ AC_DEFUN([gl_FUNC_FLOORF],
 #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_floorf) (float) = argc ? floorf : dummy;
   /* Test whether floorf (-0.0f) is -0.0f.  */
-  if (signbitf (minus_zerof) && !signbitf (floorf (minus_zerof)))
+  if (signbitf (minus_zerof) && !signbitf (my_floorf (minus_zerof)))
     return 1;
   return 0;
 }