error: any use of this value will cause an error
  --> $DIR/const-len-underflow-separate-spans.rs:7:20
   |
LL | const LEN: usize = ONE - TWO;
   | -------------------^^^^^^^^^-
   |                    |
   |                    attempt to subtract with overflow
   |
   = note: `#[deny(const_err)]` on by default

error[E0080]: evaluation of constant value failed
  --> $DIR/const-len-underflow-separate-spans.rs:11:17
   |
LL |     let a: [i8; LEN] = unimplemented!();
   |                 ^^^ referenced constant has errors

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0080`.