contract C { uint x; uint y; function g(uint _x) public { f1(_x); // If the body of function `f` is ignored while keeping the state, // the assertion is true and not reporting it would be a false negative. // However, since `f` can change the state, the state variables are also // assigned nondeterministic values after a call to `f`. // Therefore the assertion below should fail. assert(x == 0); f2(_x); assert(y == 0); // should fail } /// @custom:smtchecker abstract-function-nondet function f1(uint _x) internal { x = _x; } function f2(uint _y) internal { y = _y; } } // ==== // SMTEngine: chc // ---- // Warning 6328: (400-414): CHC: Assertion violation happens here.\nCounterexample:\nx = 1, y = 0\n_x = 0\n\nTransaction trace:\nC.constructor()\nState: x = 0, y = 0\nC.g(0)\n C.f1(0) -- internal call // Warning 6328: (429-443): CHC: Assertion violation happens here.\nCounterexample:\nx = 1, y = 1\n_x = 1\n\nTransaction trace:\nC.constructor()\nState: x = 0, y = 0\nC.g(1)\n C.f1(1) -- internal call\n C.f2(1) -- internal call