Improve math to check for overflow

makerdao · brianmcmichael · May 14, 2021 · Apr 30, 2021 · May 3, 2021 · May 3, 2021
commit 8fda89fd62e6ed113030dde400444bc2e42604f8
diff --git a/src/fuzz/DssVestEchidnaTest.sol b/src/fuzz/DssVestEchidnaTest.sol
@@ -22,12 22,13 @@ contract DssVestEchidnaTest is EchidnaInterface {
  }
 
  // --- Math ---
-
  function add(uint256 x, uint256 y) internal pure returns (uint256 z) {
- require((z = x y) >= x);
  z = x y;
  assert (z >= x); // check if there is an addition overflow
  }
  function sub(uint256 x, uint256 y) internal pure returns (uint256 z) {
- require((z = x - y) <= x);
  z = x - y;
  assert (z <= x); // check if there is a subtraction overflow
  }
 
  function test_init(uint256 _amt, uint256 _bgn, uint256 _tau, uint256 _clf) public {