| //@ build-fail |
| //@ compile-flags: -C debug-assertions |
| |
| // This function is checking that our automatic truncation does not |
| // sidestep the overflow checking. |
| |
| #![deny(arithmetic_overflow)] |
| |
| fn main() { |
| // this signals overflow when checking is on |
| let x = 1_i8 << 17; |
| //~^ ERROR: this arithmetic operation will overflow |
| |
| // ... but when checking is off, the fallback will truncate the |
| // input to its lower three bits (= 1). Note that this is *not* |
| // the behavior of the x86 processor for 8- and 16-bit types, |
| // but it is necessary to avoid undefined behavior from LLVM. |
| // |
| // We check that here, by ensuring the result has only been |
| // shifted by one place; if overflow checking is turned off, then |
| // this assertion will pass (and the compiletest driver will |
| // report that the test did not produce the error expected above). |
| assert_eq!(x, 2_i8); |
| } |
