Readline patch ported from Ruby trunk to help 2.1.1 compile on Arch linux

readline.patch

Index: ext/readline/readline.c
===================================================================
--- ext/readline/readline.c	(revision 45224)
+++ ext/readline/readline.c	(revision 45225)
@@ -1974,7 +1974,7 @@
 
     rl_attempted_completion_function = readline_attempted_completion_function;
 #if defined(HAVE_RL_PRE_INPUT_HOOK)
-    rl_pre_input_hook = (Function *)readline_pre_input_hook;
+    rl_pre_input_hook = (rl_hook_func_t *)readline_pre_input_hook;
 #endif
 #ifdef HAVE_RL_CATCH_SIGNALS
     rl_catch_signals = 0;
Index: ext/readline/extconf.rb
===================================================================
--- ext/readline/extconf.rb	(revision 45239)
+++ ext/readline/extconf.rb	(revision 45240)
@@ -19,6 +19,10 @@
   return super(func, headers)
 end
 
+def readline.have_type(type)
+  return super(type, headers)
+end
+
 dir_config('curses')
 dir_config('ncurses')
 dir_config('termcap')
@@ -94,4 +98,8 @@
 readline.have_func("rl_redisplay")
 readline.have_func("rl_insert_text")
 readline.have_func("rl_delete_text")
+unless readline.have_type("rl_hook_func_t")
+  $DEFS << "-Drl_hook_func_t=Function"
+end
+
 create_makefile("readline")
Index: ext/readline/extconf.rb
===================================================================
--- ext/readline/extconf.rb	(revision 45242)
+++ ext/readline/extconf.rb	(revision 45243)
@@ -99,6 +99,9 @@
 readline.have_func("rl_insert_text")
 readline.have_func("rl_delete_text")
 unless readline.have_type("rl_hook_func_t")
+  # rl_hook_func_t is available since readline-4.2 (2001).
+  # Function is removed at readline-6.3 (2014).
+  # However, editline (NetBSD 6.1.3, 2014) doesn't have rl_hook_func_t.
   $DEFS << "-Drl_hook_func_t=Function"
 end

The last hunk causes the patch to fail for me. Deleting that hunk, the patch succeeds, and the build succeeds, and the readline extension works (ruby 2.1.1, ubuntu 14.04). YMMV.

Anyway, the last hunk is just a comment added to the second hunk.

thanks!
and I make same patch for Ruby 2.0.0-p451.
https://gist.github.com/riocampos/b2669b26016207224f06

@mislav Since this patch is known to help those of us on Ubuntu (see rbenv/ruby-build#526 ), perhaps the title should be changed to include more than Arch ?