src/test/ui/consts/const-int-arithmetic-overflow.rs

   1 // run-pass
   2 // compile-flags: -O
   3
   4 // Make sure arithmetic unary/binary ops actually return the right result, even when overflowing.
   5 // We have to put them in `const fn` and turn on optimizations to avoid overflow checks.
   6
   7 const fn add(x: i8, y: i8) -> i8 { x+y }
   8 const fn sub(x: i8, y: i8) -> i8 { x-y }
   9 const fn mul(x: i8, y: i8) -> i8 { x*y }
  10 // div and rem are always checked, so we cannot test their result in case of overflow.
  11 const fn neg(x: i8) -> i8 { -x }
  12
  13 fn main() {
  14     const ADD_OFLOW: i8 = add(100, 100);
  15     assert_eq!(ADD_OFLOW, -56);
  16
  17     const SUB_OFLOW: i8 = sub(100, -100);
  18     assert_eq!(SUB_OFLOW, -56);
  19
  20     const MUL_OFLOW: i8 = mul(-100, -2);
  21     assert_eq!(MUL_OFLOW, -56);
  22
  23     const NEG_OFLOW: i8 = neg(-128);
  24     assert_eq!(NEG_OFLOW, -128);
  25 }