message: calling panic_if_uninhabited is not actually UB
diff: @@ -381,7 +381,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
  let ty = substs.type_at(0);
  let layout = this.layout_of(ty)?;
  if layout.abi.is_uninhabited() {
  - throw_ub_format!("Trying to instantiate uninhabited type {}", ty)
  + // FIXME: This should throw a panic in the interpreted program instead.
  + throw_unsup_format!("Trying to instantiate uninhabited type {}", ty)
  }
  }
  