If we pass wrong arguments to printf (i.e forget a comma between 2 arguments), compiler can not check it out, and main function can not be parsed.

C code:
int printf(const char* str, ...);

struct dog
{
	int a;
	int b;
};

void set_dog(struct dog* d, int x)
{
	d->b = x;
}

int main()
{
	struct dog d;
	set_dog(&d, 70);
        //printf("hello world %i\r\n", d.b); 
	printf("hello world %i\r\n" d.b); //I forget a comma
	return 0;
}