[antlr-interest] Imaginary tokens warning

[G R]

Hi,
Creating my grammar, I'm using some imaginary tokens to create nodes for my
AST.
The problem is that i got some warning with my imaginary tokens.
Here's a part of my grammar :

grammar RAGrammar;
...
divide    :    r1=relation Divide r2=relation
        ->^(Divide $r1 $r2);

AttributeList:;
RenameList:;
RenameAttribute:;

Project       :    '\\u03c0';
Select        :    '\\u03c3';
...

And the warning messages :
warning(208): RAGrammar.g:126:1: The following token definitions are
unreachable: RenameList,RenameAttribute

line 126 is the line defining RenameAttribute.
Trying to have a warning free program, I'v try to define a token section
giving the next grammar :

grammar RAGrammar;
...
divide    :    r1=relation Divide r2=relation
        ->^(Divide $r1 $r2);

tokens {
        AttributeList;
        RenameList;
        RenameAttribute;
}

Project       :    '\\u03c0';
Select        :    '\\u03c3';
...

This time i got the following errors :
error(100): RAGrammar.g:123:1: syntax error: antlr: RAGrammar.g:123:1:
unexpected token: tokens {
error(100): RAGrammar.g:124:15: syntax error: antlr: RAGrammar.g:124:15:
unexpected token: ;
error(100): RAGrammar.g:125:12: syntax error: antlr: RAGrammar.g:125:12:
unexpected token: ;
error(100): RAGrammar.g:126:17: syntax error: antlr: RAGrammar.g:126:17:
unexpected token: ;
error(106): RAGrammar.g:42:4: reference to undefined rule: divide
error(10):  internal error: org.antlr.tool.Message.toString(Message.java:124):
Assertion failed! Message ID 100 created but is not present in errorMsgIDs
or warningMsgIDs.

I'm a bit lost on this one. Could anyone give a hand ?
Thanks.
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