-# cbrtf.m4 serial 2
-dnl Copyright (C) 2012 Free Software Foundation, Inc.
+# cbrtf.m4 serial 3
+dnl Copyright (C) 2012-2013 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_FUNC_CBRT])
+ dnl Persuade glibc <math.h> to declare cbrtf().
+ AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
dnl Test whether cbrtf() exists. Assume that cbrtf(), if it exists, is
dnl defined in the same library as cbrt().
save_LIBS="$LIBS"