error[E0599]: the function or associated item `max_encoded_len` exists for struct `Generic<NotMel>`, but its trait bounds were not satisfied
  --> $DIR/not_mel.rs:13:29
   |
5  | struct NotMel;
   | -------------- doesn't satisfy `NotMel: MaxEncodedLen`
...
8  | struct Generic<T> {
   | -----------------
   | |
   | function or associated item `max_encoded_len` not found for this
   | doesn't satisfy `Generic<NotMel>: MaxEncodedLen`
...
13 |     let _ = Generic::<NotMel>::max_encoded_len();
   |                                ^^^^^^^^^^^^^^^ function or associated item cannot be called on `Generic<NotMel>` due to unsatisfied trait bounds
   |
   = note: the following trait bounds were not satisfied:
           `NotMel: MaxEncodedLen`
           which is required by `Generic<NotMel>: MaxEncodedLen`
   = help: items from traits can only be used if the trait is implemented and in scope
   = note: the following trait defines an item `max_encoded_len`, perhaps you need to implement it:
           candidate #1: `MaxEncodedLen`