From: "Berger, Daniel" <Daniel.Berger@...>
Date: 2007-12-11T07:43:55+09:00
Subject: Re: aliasing methods that don't exist

 > -----Original Message-----
> From: Eric Hodel [mailto:drbrain@segment7.net] 
> Sent: Monday, December 10, 2007 3:28 PM
> To: ruby-core@ruby-lang.org
> Subject: aliasing methods that don't exist
> 
> class X; alias_method :a, :a; end
> class X; alias a a; end
> 
> Is this a bug?

Hehe, I'd say so. I'm pretty sure it's this line in eval.c/rb_alias
causing it:

if (name == def) return;

I think this (untested) patch fixes it. Basically, it just moves the
check until after verification that the method exists.

>diff -u eval.orig eval.c
--- eval.orig   Sat Sep 22 17:01:50 2007
+++ eval.c      Mon Dec 10 15:40:04 2007
@@ -2158,7 +2158,6 @@
     VALUE singleton = 0;

     rb_frozen_class_p(klass);
-    if (name == def) return;
     if (klass == rb_cObject) {
        rb_secure(4);
     }
@@ -2171,6 +2170,9 @@
     if (!orig || !orig->nd_body) {
        print_undef(klass, def);
     }
+
+    if (name == def) return;
+
     if (FL_TEST(klass, FL_SINGLETON)) {
        singleton = rb_iv_get(klass, "__attached__");
     }

Regards,

Dan


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