error: `IceEnum` is forbidden as the type of a const generic parameter --> $DIR/issue-74255.rs:18:31 | LL | fn ice_struct_fn() {} | ^^^^^^^ | = note: the only supported types are integers, `bool` and `char` = help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types error: aborting due to previous error