#include <sys/cdefs.h>

void die(void);
#define A(e) (__predict_true(e) ? (void)0 : die())

class Foo {
	int val;
public:
	Foo(int a) {
		val = a;
	}
	explicit operator bool() const { return val < 0; }
};

int main()
{
	auto x = Foo(42);

	A(x);
	return 0;
}