SIGSEGV while creating a parser-tree - c++

Question

I am trying to create a parser-generator using flex/bison. This is my partial parser.y code:
func_definition : type_specifier ID LPAREN parameter_list RPAREN compound_statement
{
$$=new Symbol_info();
$$->code+="PROC:"+ $2->symbol+"\n";
if($2->symbol!="main")
{
$$->code+="PUSH AX\n";
$$->code+="PUSH BX\n";
$$->code+="PUSH CX\n";
$$->code+="PUSH DX\n";
}
$$->code += $6->code ;
if($2->symbol!="main") {
$$->code+="POP DX\n";
$$->code+="POP CX\n";
$$->code+="POP BX\n";
$$->code+="POP AX\n";
}
fprintf(parseLog, "GRAMMER RULE: func_definition -> type_specifier ID LPAREN parameter_list RPAREN compound_statement \n");
}
;
And this is my partial lex.l code.
{id} {
Symbol_info *s= new Symbol_info(yytext, "ID");
yylval = (YYSTYPE)s;
return ID;
}
And this is my partial symbol_table.h code
class SymbolInfo{
string type;
string symbol;
public:
string code;
SymbolInfo *next;
SymbolInfo(){
symbol="";
type="";
code="";
}
SymbolInfo(string symbol, string type){
this->symbol=symbol;
this->type=type;
code="";
}
SymbolInfo(char *symbol, char *type){
this->symbol=string(symbol);
this->type= string(type);
code="";
}
SymbolInfo(const SymbolInfo *sym){
symbol=sym->symbol;
type=sym->type;
code=sym->code;
}
So, when I create a program, I get a SIGSEGV segmentation fault. (Address boundary error). It appears that I get that error when I try to access the yylval returned to me by the lex function.

Answer 1

I tried to run this code on an Ubuntu 64-bit instance (Ubuntu 17.10). I don't know why but the same code runs fine on a 32 bit system (Ubuntu 14.10).
Maybe it's because of the large Integer sizes. Here is the code if you're interested.