error: `IceEnum` is forbidden as the type of a const generic parameter
  --> $DIR/issue-74255.rs:15:31
   |
LL |     fn ice_struct_fn<const I: IceEnum>() {}
   |                               ^^^^^^^
   |
   = note: the only supported types are integers, `bool` and `char`
   = note: more complex types are supported with `#[feature(const_generics)]`

error: aborting due to previous error