Thread: error: conflicting types

I'm trying to code a part of a compiler, and I'm getting that error message when I try to compile a test program.

The program is at www.geocities.com/alienjedi1/mini-algol-60.zip

The URL is a link to a zip file containing all the files (even though the problem is with just two of them). The complete error message is in the file called error.

The error message is nothing specific to the project (it's not from any compiler building specific tools I'm using), just from GCC in unix.

Could someone please tell me why I'm getting that error. The error is in y.tab.c and mini-algol-60.y Thanks so much.

Error:

Code:

mini-algol-60.y:31: error: conflicting types for 'YYSTYPE'
y.tab.h:6: error: previous declaration of 'YYSTYPE' was here
mini-algol-60.y:122: error: conflicting types for 'yylval'
y.tab.h:7: error: previous declaration of 'yylval' was here
mini-algol-60.y:122: error: conflicting types for 'yylval'
y.tab.h:7: error: previous declaration of 'yylval' was here
make: *** [algol.o] Error 1

y.tab.h

Code:

typedef union
#ifdef __cplusplus
	YYSTYPE
#endif
 { int i; tree p; } YYSTYPE;
extern YYSTYPE yylval;

mini-algol-60.y line 122

Code:

{ $$ = buildIntTree( IntConst, $1 ); }

$$ is of type tree.

Relevant structures used.

Code:

typedef struct tree_node
{
	int	kind, value;
	struct tree_node *first, *second, *third, *next;
} node;

typedef node* tree;

tree buildIntTree (int kind, int val)
{
	tree p = (tree)malloc(sizeof (node));
	p->kind = kind;
	p->value = val;
	p->first = p->second = p->third = NULL;
	p->next = NULL;
	return p;
}

Well you need yacc/bison to compile a .y file, which will produce a .c file you can then compile with your C compiler.

I did use yacc. I'm sorry for not being specific. I'm trying to compile algol.c. I wrote a make file that ran yacc (and lex for whatever that's worth), and then compile algol.c to produce a parser. It has no trouble making the y.tab.h and y.tab.c files. The problem lies with compiling algol.c. It's giving that wierd error several times.

My question is what is the nature of that error message? What causes that kind of error? If I understood the problem better, then I could find a solution.

Another interesting fact about the errors I listed - I'm not referencing the .y file anywhere. The errors are really coming from the y.tab.* files.

This error message occurs when you don not make a function prototype decleration. Try to add something like <return_value> myfunction(type arg....) at the begining of your code.

My IDE (Dev-C++) gave me the same error when I did not make a function prototye decelration at begining fo my code (but the function implemenration was after main()).