message: rm custom `intrinsics::discriminant_value`
diff: @@ -248,12 +248,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
  }
  }
  - "discriminant_value" => {
  - let place = this.deref_operand(args[0])?;
  - let discr_val = this.read_discriminant(place.into())?.0;
  - this.write_scalar(Scalar::from_uint(discr_val, dest.layout.size), dest)?;
  - }
  -
  #[rustfmt::skip]
  | "sinf32"
  | "fabsf32"
  