math: Ensure declarations of math functions.

[gnulib.git] / m4 / frexpf.m4

diff --git a/m4/frexpf.m4 b/m4/frexpf.m4
index 5a37b39..c7aa59d 100644 (file)
--- a/m4/frexpf.m4
+++ b/m4/frexpf.m4
@@ -1,4 +1,4 @@
-# frexpf.m4 serial 3
+# frexpf.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,
@@ -9,6 +9,9 @@ AC_DEFUN([gl_FUNC_FREXPF],
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_FREXP])
 
+  dnl Persuade glibc <math.h> to declare frexpf().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Test whether frexpf() exists. We cannot assume that frexpf(), if it
   dnl exists, is defined in the same library as frexp(). This is not the case
   dnl on NetBSD, OpenBSD.