void abort() { }; extern unsigned int __VERIFIER_nondet_uint(); /*@ requires ((\old(cond) != 0)) && (cond != 0); ensures ((\old(cond) != 0)) && (1); @*/ void __VERIFIER_assert(int cond) { if (!(cond)) { ERROR: {/*@ assert(0); */;abort();} } return; } int main() { unsigned int w = __VERIFIER_nondet_uint(); unsigned int x = w; unsigned int y = __VERIFIER_nondet_uint(); unsigned int z = y; /*@ loop invariant (((z == y) && (x == w))); @*/ while (__VERIFIER_nondet_uint()) { if (__VERIFIER_nondet_uint()) { ++w; ++x; } else { --y; --z; } } __VERIFIER_assert(w == x && y == z); return 0; }