==== Source: base ==== contract Base { uint x; address a; function f() internal returns (uint) { a = address(this); ++x; return 2; } } ==== Source: der ==== pragma experimental SMTChecker; import "base"; contract Der is Base { function g(uint y) public { require(x < 10); // added to restrict the search space and avoid non-determinsm in Spacer x += f(); assert(y > x); } } // ---- // Warning 6328: (der:205-218): CHC: Assertion violation happens here.\nCounterexample:\nx = 3, a = 0\ny = 0\n\nTransaction trace:\nDer.constructor()\nState: x = 0, a = 0\nDer.g(0)\n Base.f() -- internal call