-# tanhf.m4 serial 1
-dnl Copyright (C) 2011 Free Software Foundation, Inc.
+# tanhf.m4 serial 2
+dnl Copyright (C) 2011-2013 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_TANH])
+ dnl Persuade glibc <math.h> to declare tanhf().
+ AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
dnl Test whether tanhf() exists. Assume that tanhf(), if it exists, is
dnl defined in the same library as tanh().
save_LIBS="$LIBS"