math: Ensure declarations of math functions.

[gnulib.git] / m4 / ldexpf.m4

diff --git a/m4/ldexpf.m4 b/m4/ldexpf.m4
index 0ffa591..1065b66 100644 (file)
--- a/m4/ldexpf.m4
+++ b/m4/ldexpf.m4
@@ -1,4 +1,4 @@
-# ldexpf.m4 serial 1
+# ldexpf.m4 serial 2
 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_LDEXPF],
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_LDEXP])
 
+  dnl Persuade glibc <math.h> to declare ldexpf().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Test whether ldexpf() exists. We cannot assume that ldexpf(), if it
   dnl exists, is defined in the same library as ldexp(). This is not the case
   dnl on FreeBSD, NetBSD, OpenBSD.