math: Ensure declarations of math functions.

[gnulib.git] / m4 / fabsf.m4

diff --git a/m4/fabsf.m4 b/m4/fabsf.m4
index ef577a9..d2e7e7a 100644 (file)
--- a/m4/fabsf.m4
+++ b/m4/fabsf.m4
@@ -1,4 +1,4 @@
-# fabsf.m4 serial 2
+# fabsf.m4 serial 3
 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,
@@ -9,6 +9,9 @@ AC_DEFUN([gl_FUNC_FABSF],
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_FABS])
 
+  dnl Persuade glibc <math.h> to declare fabsf().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Test whether fabsf() exists. We cannot assume that fabsf(), if it
   dnl exists, is defined in the same library as fabs(). This is not the case
   dnl on FreeBSD, NetBSD, OpenBSD.