This is the patch for MacRuby that is implemented rb_define_method. But not support to call method with blocks.

rb_define_method-for-macruby.patch

diff --git a/class.c b/class.c
index ed7ccaf..e4bdceb 100644
--- a/class.c
+++ b/class.c
@@ -1003,7 +1003,7 @@ name_to_sel(const char *name, const int arity)
     return sel_registerName(name);
 }
 
-static void
+static rb_vm_method_node_t *
 rb_objc_add_method(VALUE klass, const char *name, void *imp, const int arity,
 		   const int noex, bool direct)
 {
@@ -1014,8 +1014,8 @@ rb_objc_add_method(VALUE klass, const char *name, void *imp, const int arity,
     NODE *body = rb_vm_cfunc_node_from_imp((Class)klass, arity, (IMP)imp, noex);
     rb_objc_retain(body);
 
-    rb_vm_define_method((Class)klass, name_to_sel(name, arity), (IMP)imp,
-	    body, direct);
+    return rb_vm_define_method((Class)klass, name_to_sel(name, arity), (IMP)imp,
+                               body, direct);
 }
 
 void
@@ -1046,28 +1046,38 @@ rb_objc_define_module_function(VALUE module, const char *name, void *imp,
     rb_objc_define_method(*(VALUE *)module, name, imp, arity);
 }
 
+static rb_vm_method_node_t *
+rb_mri_add_method(VALUE klass, const char *name, void *imp, const int arity,
+                  const int noex, bool direct)
+{
+    rb_vm_method_node_t *node =
+        rb_objc_add_method(klass, name, imp, arity, noex, direct);
+    node->flags |= VM_METHOD_MRI;
+    return node;
+}
+
 void
 rb_define_method_id(VALUE klass, ID name, VALUE (*func)(ANYARGS), int argc)
 {
-    rb_add_method(klass, name, NEW_CFUNC(func,argc), NOEX_PUBLIC);
+    rb_mri_add_method(klass, rb_id2name(name), func, argc, NOEX_PUBLIC, false);
 }
 
 void
 rb_define_method(VALUE klass, const char *name, VALUE (*func)(ANYARGS), int argc)
 {
-    rb_add_method(klass, rb_intern(name), NEW_CFUNC(func, argc), NOEX_PUBLIC);
+    rb_mri_add_method(klass, name, func, argc, NOEX_PUBLIC, false);
 }
 
 void
 rb_define_protected_method(VALUE klass, const char *name, VALUE (*func)(ANYARGS), int argc)
 {
-    rb_add_method(klass, rb_intern(name), NEW_CFUNC(func, argc), NOEX_PROTECTED);
+    rb_mri_add_method(klass, name, func, argc, NOEX_PROTECTED, false);
 }
 
 void
 rb_define_private_method(VALUE klass, const char *name, VALUE (*func)(ANYARGS), int argc)
 {
-    rb_add_method(klass, rb_intern(name), NEW_CFUNC(func, argc), NOEX_PRIVATE);
+    rb_mri_add_method(klass, name, func, argc, NOEX_PRIVATE, false);
 }
 
 void
diff --git a/dispatcher.cpp b/dispatcher.cpp
index 0a9202f..cd346c8 100644
--- a/dispatcher.cpp
+++ b/dispatcher.cpp
@@ -156,6 +156,51 @@ __rb_vm_rcall(VALUE self, SEL sel, IMP pimp, const rb_vm_arity_t &arity,
     abort();
 }
 
+static force_inline VALUE
+__rb_vm_rcall_nosel(VALUE self, SEL sel, IMP pimp, const rb_vm_arity_t &arity,
+		    int argc, const VALUE *argv)
+{
+    if ((arity.real != argc) || (arity.max == -1)) {
+	VALUE *new_argv = (VALUE *)alloca(sizeof(VALUE) * arity.real);
+	__rb_vm_fix_args(argv, new_argv, arity, argc);
+	argv = new_argv;
+	argc = arity.real;
+    }
+
+    assert(pimp != NULL);
+
+    VALUE (*imp)(VALUE, ...) = (VALUE (*)(VALUE, ...))pimp;
+
+    switch (argc) {
+	case 0:
+	    return (*imp)(self);
+	case 1:
+	    return (*imp)(self, argv[0]);
+	case 2:
+	    return (*imp)(self, argv[0], argv[1]);
+	case 3:
+	    return (*imp)(self, argv[0], argv[1], argv[2]);
+	case 4:
+	    return (*imp)(self, argv[0], argv[1], argv[2], argv[3]);
+	case 5:
+	    return (*imp)(self, argv[0], argv[1], argv[2], argv[3], argv[4]);
+	case 6:
+	    return (*imp)(self, argv[0], argv[1], argv[2], argv[3], argv[4], argv[5]);
+	case 7:
+	    return (*imp)(self, argv[0], argv[1], argv[2], argv[3], argv[4], argv[5], argv[6]);
+	case 8:
+	    return (*imp)(self, argv[0], argv[1], argv[2], argv[3], argv[4], argv[5], argv[6], argv[7]);
+	case 9:
+	    return (*imp)(self, argv[0], argv[1], argv[2], argv[3], argv[4], argv[5], argv[6], argv[7], argv[8]);
+	case 10:
+	    return (*imp)(self, argv[0], argv[1], argv[2], argv[3], argv[4], argv[5], argv[6], argv[7], argv[8], argv[9]);
+	case 11:
+	    return (*imp)(self, argv[0], argv[1], argv[2], argv[3], argv[4], argv[5], argv[6], argv[7], argv[8], argv[9], argv[10]);
+    }	
+    printf("invalid argc %d\n", argc);
+    abort();
+}
+
 static void
 vm_gen_bs_func_types(int argc, const VALUE *argv,
 	bs_element_function_t *bs_func, std::string &types)
@@ -407,6 +452,28 @@ __rb_vm_ruby_dispatch(VALUE top, VALUE self, SEL sel,
 	return Qnil;
     }
 
+    if (node->flags & VM_METHOD_MRI) {
+	if ((node->flags & VM_METHOD_FBODY) && arity.max != arity.min) {
+	    // Calling a function defined with rb_objc_define_method with
+	    // a negative arity, which means a different calling convention.
+	    if (arity.real == 2) {
+		return ((VALUE (*)(int, const VALUE *, VALUE))node->ruby_imp)
+		    (argc, argv, self);
+	    }
+	    else if (arity.real == 1) {
+		return ((VALUE (*)(VALUE, ...))node->ruby_imp)
+		    (rb_ary_new4(argc, argv), self);
+	    }
+	    else {
+		printf("invalid negative arity for C function %d\n",
+		       arity.real);
+		abort();
+	    }
+	}
+
+	return __rb_vm_rcall_nosel(self, sel, node->ruby_imp, arity, argc, argv);
+    }
+
     if ((node->flags & VM_METHOD_FBODY) && arity.max != arity.min) {
 	// Calling a function defined with rb_objc_define_method with
 	// a negative arity, which means a different calling convention.
diff --git a/ext/readline/extconf.rb b/ext/readline/extconf.rb
index 4e4c45d..24a4485 100644
--- a/vm.h
+++ b/vm.h
@@ -61,6 +61,7 @@ typedef struct {
 #define VM_METHOD_PRIVATE	2 // method is private (runtime)
 #define VM_METHOD_PROTECTED	4 // method is protected (runtime)
 #define VM_METHOD_FBODY		8 // method has a MRI C prototype (compilation) 
+#define VM_METHOD_MRI		16 // method has a MRI C arguments (compilation) 
 
 static inline int
 rb_vm_noex_flag(const int noex)