From: SASADA Koichi <ko1@...>
Date: 2012-04-09T14:11:24+09:00
Subject: [ruby-core:44210] Re: [ruby-trunk - Feature #5716][Open] duplicated when clause is ignored -> Report which clause it is specifically.

Thank you for your comment.

I added a small hint on it because if duplicated object was too big, the
output should be ugly.

Does it help you?

# sample code
case nil
when 1
when 1, 1
when 1, 1, 1, 1
when 1, 1
end

#=>
../trunk/test.rb:1: warning: duplicated when clause (#1) is ignored
../trunk/test.rb:1: warning: duplicated when clause (#2) is ignored
../trunk/test.rb:1: warning: duplicated when clause (#3) is ignored
../trunk/test.rb:1: warning: duplicated when clause (#4) is ignored
../trunk/test.rb:1: warning: duplicated when clause (#5) is ignored
../trunk/test.rb:1: warning: duplicated when clause (#6) is ignored
../trunk/test.rb:1: warning: duplicated when clause (#7) is ignored
../trunk/test.rb:1: warning: duplicated when clause (#8) is ignored


Patch:
Index: compile.c
===================================================================
--- compile.c	(revision 35267)
+++ compile.c	(working copy)
@@ -1454,8 +1454,9 @@
 				    rb_hash_aset(map, obj, INT2FIX(lobj->position - (pos+len)));
 				}
 				else {
+				    int n = i/2;
 				    rb_compile_warning(RSTRING_PTR(iseq->filename), iobj->line_no,
-						       "duplicated when clause is ignored");
+						       "duplicated when clause (#%d) is ignored", n);
 				}
 			    }
 			    hide_obj(map);


(2011/12/06 19:07), markus heiler wrote:
> 
> Issue #5716 has been reported by markus heiler.
> 
> ----------------------------------------
> Feature #5716: duplicated when clause is ignored -> Report which clause it is specifically.
> http://redmine.ruby-lang.org/issues/5716
> 
> Author: markus heiler
> Status: Open
> Priority: Low
> Assignee: 
> Category: 
> Target version: 
> 
> 
> In latest Ruby 1.9.3, if you have warnings enabled, you get information like this here:
> 
> foobar.rb:24: warning: duplicated when clause is ignored
> 
> This error comes from the file:
> 
>   compile.c
> 
> 
> rb_compile_warning(RSTRING_PTR(iseq->filename), iobj->line_no,
>     "duplicated when clause is ignored");
> 
> 
> This is called, it seems, when the prior function fails:
> 
>   rb_hash_aset(map, obj, INT2FIX(lobj->position - (pos+len)));
> 
> 
> As a user of Ruby, the warning should be better.
> 
> Rather than:
> 
>   foobar.rb:24: warning: duplicated when clause is ignored
> 
> I would like to see:
> 
>   foobar.rb:24: warning: duplicated when clause 'foo' is ignored.
> 
> This way, I can scan through the file with the case/when structure
> and correct this error. But right now, if you have a very long 
> case/when structure, you have no idea WHICH clause is duplicated.
> 
> The warning message just vaguely says that there is, and this is
> not very helpful information.
> 
> 


-- 
// SASADA Koichi at atdot dot net