Thread: YACC abstract syntax tree error: line 47: fatal: must specify type for Begin

I am working on a YACC file for a compiler independent study. I have received the above error. I am pretty sure the way I am starting off the tree is incorrect and I am not sure how I would correct the issue. The CFG Production for the first tow items happen to be:

Code:

program -> block
block -> "begin" optdecls stmts "end"

The portion of the yacc file is as follows:

Code:

%token <i> Ident 1 IntConst 2
%token <f> RealConst 3 
%token     And 4 Array 5 Begin 6 Boolean 7 Div 8 Do 9 Else 10
%token     End 11 False 12 For 13 Goto 14 If 15
%token     Imply 16 Integer 17 Label 18 Not 19 Or 20
%token     Own 21 Procedure 22 Real 23 Step 24 String 25
%token     Then 26 True 27 Until 28 Value 29 While 30
%token     Plus 31 Minus 32 Mult 33 Divide 34 Less 35
%token     LessEq 36 Great 37 GreatEq 38 Eq 39 NotEq 40
%token     Comma 41 Colon 42 Semi 43 LParan 44 RParan 45
%token     LBrak 46 RBrak 47 Assign 48 


%{

#include "tree.h"

extern tree root;


%}

%start program

%union { tree t; int i; float f; }

%type <t>       block optdecls decl vardecl type idlist arraydecl arraylist arrayseg
%type <t>       stmts stmt u_stmt assign dummy for_stmt if_stmt var factor term sum
%type <t>       brel relation bsecond bfactor bterm expr a_expr

%%

program 
        : block
                { root = $1; }
        ;

block
        : Begin optdecls stmts End
                { $$ = buildTree(Begin, $1, $2, NULL); }    <----ERROR here, line 47
        ;

optdecls
        : /* empty */
                { $$ = NULL; }
        | decl Semi optdecls
                { $$ = buildTree($1, Semi); $$->next = $3; }

After looking over some code my professor has shown us, I noticed he does not specify a type for his "begin" in his version of a different yacc file. I am not sure how to correct this. Can someone show me what is my error and how I would correct it? If you need more code, I will repost. Thanks.

I figured it out. Begin needs to be in the token declaration with a value:

Code:

%token <i> Ident 1 IntConst 2 Begin 6