An example of messy const-correctness in C

const.c

struct bar { int foo; };

const struct bar fizz = { 10 };

void baz(struct bar * a) {
	a->foo = 30;
}

int main() {
	//fizz.foo = 20; // does not compile
	baz(&fizz); // complies with warnings; WILL segfault!
}