Large amount of errors compiling lex and yacc files - c

Question

I'm trying to make a simple calculator with yacc/lex, but I keep getting a large amount of errors with a lot of them saying the errors are in the generated files.
I run gcc lex.yy.c y.tab.c -o minicalc and get errors like
bas.y:34:16: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘{’ token
int main(void) {
y.tab.c:499:2: error: expected declaration specifiers before ‘;’ token
};
These are the most common but there are many more. The thing is, I'm getting errors like
In file included from lex.yy.c:459:0:
/usr/include/unistd.h: In function ‘yyerror’:
/usr/include/unistd.h:258:22: error: storage class specified for parameter ‘useconds_t’
typedef __useconds_t useconds_t;
^~~~~~~~~~
that make it seem like the error is not in my code.
This is my lex code:
%{
#include <stdlib.h>
#include "y.tab.h"
void yyerror(char *)
%}
%%
/* a is value of last expresion */
a {
yyval = *yytext - 'a';
return LAST;
}
/* integers */
[0-9]+ {
yyval = atoi(yytext);
return INTEGER;
}
/* operators */
[-+()=/*\n] { return *yytext; }
/* skip whitespace */
[ \t] { ; }
/* all else is error */
. yyerror("invalid character");
%%
int yywrap(void) {
return 1;
}
and this is my yacc code:
%token INTEGER LAST
%left '+' '-'
%left '*' '/'
%{
void yyerror(char *)
int yylex(void);
int lastval;
%}
%%
program:
program expr '\n' { lastval = $2; }
|
;
expr:
INTEGER
| LAST { $$ = lastval; }
| expr '+' expr { $$ = $1 + $3; }
| expr '-' expr { $$ = $1 - $3; }
| expr '*' expr { $$ = $1 * $3; }
| expr '/' expr { $$ = $1 / $3; }
| '(' expr ')' { $$ = $2; }
;
%%
void yyerror(char *) {
fprintf(stderr, "%s\n", s);
}
int main(void) {
yyparse();
return 0;
}
Thanks in advance.

Answer 1

You're missing a semicolon after void yyerror(char *) in both the .y and the .l file. So the compiler expects a ; on the lines that come after it in the generated code, leading to the error messages you're seeing.