[antlr-interest] parse error because of AST rewrite rules?

[Stefan Oestreicher]

Hi,

I'm working on a grammar for a simple programming language and I'd like 
to support variable declarations like that:
int a, b = 3

I started out with the following rule:

variableDeclaration
    :   type ID ( COMMA ID )* ( ASSIGN expression )?
    ;

Now I'd like to generate an AST for the above example that looks like that:
^(VAR_DEF int a)
^(VAR_DEF int b)
^(= a 3)
^(= b a)

So I've tried it with the following rules:

--- grammar snippet ---
variableDeclaration
    :    simpleVariableDeclaration
    |    listVariableDeclaration
    ;
   
simpleVariableDeclaration
    :    type ID ( ASSIGN expression )?
        ->    ^(VAR_DEF ID type)
                ^(ASSIGN ID expression)?
    ;   
   
listVariableDeclaration
    :    type first=ID ( COMMA other+=ID )+ 
listVariableAssignment[$first, $other]?
        ->    ^(VAR_DEF $first type)
                ^(VAR_DEF $other type)
            listVariableAssignment?
    ;
   
listVariableAssignment[pANTLR3_COMMON_TOKEN first, pANTLR3_VECTOR other]
    :    ASSIGN expression
        ->    ^(ASSIGN {$first} expression)
                ^(ASSIGN {$other} {$first})+
    ;
--- /grammar snippet ---

I've also tried this simpler variant for listVariableDeclaration:

--- grammar snippet ---
listVariableDeclaration
    :    (    type first=ID ( COMMA other+=ID )+
            ->    ^(VAR_DEF $first type)
                    ^(VAR_DEF $other type)
         )
         (    ASSIGN expression
             ->   ^(ASSIGN $first expression)
                    ^(ASSIGN $other $first)+
         )?
    ;
--- /grammar snippet ---

The modified rules still produce a correct parse tree in the interpreter 
but the generated code raises a parse error. It either complains about 
the assignment operator after the ID list or about the semicolon the 
terminates the declaration (not shown in the example).
If I remove the rewrite rules there is no problem.

I'd appreciate any hint about what I'm doing wrong. I'm using the C 
target btw, version 3.1.3.

Thanks,

Stefan