nonterminal symbol types

[olivier laporte]

Hello everybody,
I'm facing a problem in the parser I'm writting for which I haven't found
any valuable help in any forum I tried.
To be brief, here is an extract of the code:

%union
{
    int             ival;
    const char*     sval;
};
%type<ival> .mode.

%%

formal_port_element
        : .SIGNAL. {g_list_type = Parser::PORT;}
          identifier_list
          Colon {g_list_type = Parser::UNKNOWN;}
          .mode. { design.portSpecs($4);}
          type_mark
          .constraint.
          .BUS.
          .VarAsgn__expression.
        ;

.mode.
        :/*empty*/{ $$ = VHDLDefs::NONE;}
        | IN { $$ = VHDLDefs::IN;}
        | OUT  { $$ = VHDLDefs::OUT;}
        | INOUT  { $$ = VHDLDefs::INOUT;}
        | BUFFER  { $$ = VHDLDefs::NONE;}
        | LINKAGE  { $$ = VHDLDefs::NONE;}
        ;

My error is the following : $4 of 'formal_port_element' has no declared
type.
Which seems strange to me as $4 is '.mode.' rule, which is typed <ival> and
every $$ = VHDLDefs::X actions in this rule are correct according to bison.
I tried with $1 to $8 to check if anything change and weirdly, with $6 the
code pass whereas $7 and $8 are 'out of range'.

Thanks for the time you might spend on this problem,

                 Olivier LAPORTE.