Thread: How can I enforce type safety?

Take this code snippet as an example:

Code:

#include<stdio.h>

typedef unsigned foo_t;
typedef unsigned bar_t;

void func(foo_t foo) {
    printf("foo=%u\n", foo);
}

int main(int argc, char* argv[]) {

    bar_t bar = 0;
    func(bar);
    return 0;
}

When I compile this with gcc -Wall it won't even warn me or anything...

How can I make this raise an error, or at least a warning?

The only thing that typedef does is create aliases. If you create multiple aliases for the same type, then nothing is really wrong and it's your own fault. Plus, even if you made them different integer types you still have to consider integer promotion.

Can you suggest different method by which the above code would at least raise a warning by the compiler?

Originally Posted by Absurd

Can you suggest different method by which the above code would at least raise a warning by the compiler?

Code:

#include <stdio.h>
 
typedef struct { unsigned x; } foo_t;
typedef struct { unsigned x; } bar_t;
 
void func(foo_t *foo) {
    printf("foo=%u\n", foo->x);
}
 
int main(void) {
    bar_t bar = {42};
    func(&bar);
    return 0;
}

I thought about using structs, but that involves syntax changes that would require changing an existing code.
Isn't there a way to achieve the same results with primitives?