error: `::Identity` is forbidden as the type of a const generic parameter --> $DIR/projection-as-arg-const.rs:13:21 | LL | pub fn foo::Identity>() { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = note: the only supported types are integers, `bool` and `char` = help: more complex types are supported with `#![feature(adt_const_params)]` error: aborting due to previous error