Using api.token.constructor for tokens without arguments.

[Slava Barinov]

Hello,

 I'm experimenting with bison+flex and met an issue: bison won't provide a
 token type info.  So the situation: I've got a calc++ example and started to
 simplify it. For example there are two operations + and - which will increase
 and decrease global variables (no arguments needed) so there are lines in
 lex.ll

"+"       return yy::parser::make_INC(loc);
"-"       return yy::parser::make_DEC(loc);

 and corresponding

%define api.token.constructor
%define api.value.type variant
%define parse.assert
   ...

%token INC DEC
   ...
stmts:        stmt {};
    |    stmts stmt {};
    ;
stmt:         op
    ;
op:        val_op
    ;
val_op:        INC {driver.addOp($1);}
    |    DEC {driver.addOp($1);}
    ;

  in parse.yy.

  Parser generation is fine, I get the line in parse.cpp:
driver.addOp(yystack_[0].value);

  And after running the debug output prints
$1 = token INC (1.187-188: )

  but the yytypeid_ in variant coming to addOp is zero. So `as<token>()' is not
  applicable (segfault) and I can't detect which token it is. Should the token
  constructor work for such cases or it's designed only for tokens followed by
  arguments?

Thank you,
Slava Barinov