Completer implement for reference prevents any other implement for <T:SomeTrait>

[suikabreaker]

impl<'c, C> rustyline::completion::Completer for &'c C

This stops me from implement completer like this:

error[E0119]: conflicting implementations of trait `rustyline::completion::Completer` for type `&_`:
  --> src\main.rs:81:1
   |
81 | impl<T: CandidateList> Completer for T {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: conflicting implementation in crate `rustyline`:
           - impl<'c, C> rustyline::completion::Completer for &'c C
             where C: rustyline::completion::Completer, C: ?Sized;
   = note: downstream crates may implement trait `CandidateList` for type `&_`

Actually it prevents any kind of implementation like this.