message: Don't pretend that casts to bool are a thing
diff: @@ -46,9 +46,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
  fn cast_int(&self, v: u128, ty: ty::Ty<'tcx>, negative: bool) -> EvalResult<'tcx, PrimVal> {
  use rustc::ty::TypeVariants::*;
  match ty.sty {
  - TyBool if v == 0 => Ok(PrimVal::from_bool(false)),
  - TyBool if v == 1 => Ok(PrimVal::from_bool(true)),
  - TyBool => Err(EvalError::InvalidBool),
  + // Casts to bool are not permitted by rustc, no need to handle them here.
  TyInt(IntTy::I8) => Ok(PrimVal::Bytes(v as i128 as i8 as u128)),
  TyInt(IntTy::I16) => Ok(PrimVal::Bytes(v as i128 as i16 as u128)),
  