math: Ensure declarations of math functions.

[gnulib.git] / m4 / modff.m4

diff --git a/m4/modff.m4 b/m4/modff.m4
index 3b117ec..2d4fc72 100644 (file)
--- a/m4/modff.m4
+++ b/m4/modff.m4
@@ -1,4 +1,4 @@
-# modff.m4 serial 3
+# modff.m4 serial 4
 dnl Copyright (C) 2011-2012 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -10,6 +10,9 @@ AC_DEFUN([gl_FUNC_MODFF],
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_MODF])
 
+  dnl Persuade glibc <math.h> to declare modff().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Test whether modff() exists. We cannot assume that modff(), if it
   dnl exists, is defined in the same library as modf(). This is not the case
   dnl on FreeBSD, NetBSD, OpenBSD.