diff -r -U1 gcl.orig/o/gcl_readline.d gcl/o/gcl_readline.d
--- gcl.orig/o/gcl_readline.d	2013-11-11 21:55:48.000000000 +0700
+++ gcl/o/gcl_readline.d	2014-03-30 18:29:42.131967005 +0700
@@ -53,2 +53,9 @@
 
+/* Deprecated CPPFunction disappeared in libreadline-6.3 */
+#if defined(_RL_FUNCTION_TYPEDEF)
+#define RL_COMPLETION_FUNC_T rl_completion_func_t
+#else
+#define RL_COMPLETION_FUNC_T CPPFunction
+#endif
+
 int readline_on = 0;		/* On (1) or off (0) */
@@ -471,3 +478,3 @@
 #ifdef RL_COMPLETION
-  rl_attempted_completion_function = (CPPFunction *)rl_completion;
+  rl_attempted_completion_function = (RL_COMPLETION_FUNC_T *)rl_completion;
 #endif