slide-rs/atom

can not use Arc<dyn trait> with atom

jiacai2050 opened this issue · 1 comments

jiacai2050 commented

Demo

trait Engine {
    fn eval(&self) -> String;
}

struct JSEngine {
    name: String,
}

impl Engine for JSEngine {
    fn eval(&self) -> String {
        "js eval".to_string()
    }
}

fn main() {
    let engine: Arc<dyn Engine> = Arc::new(JSEngine {
        name: "js1".to_string(),
    });
    println!("Results: {}", engine.eval());

    let shared_atom = Atom::new(engine);
}
error[E0277]: the size for values of type `dyn Engine` cannot be known at compilation time
  --> src/bin/main.rs:36:33
   |
36 |     let shared_atom = Atom::new(engine);
   |                                 ^^^^^^ doesn't have a size known at compile-time
   |
   = help: the trait `std::marker::Sized` is not implemented for `dyn Engine`
   = note: required because of the requirements on the impl of `atom::IntoRawPtr` for `std::sync::Arc<dyn Engine>`
   = note: required by `atom::Atom::<P>::new`

error[E0277]: the size for values of type `dyn Engine` cannot be known at compilation time
  --> src/bin/main.rs:36:23
   |
36 |     let shared_atom = Atom::new(engine);
   |                       ^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
   | 
  :::~/.cargo/registry/src/github.com-1ecc6299db9ec823/atom-0.4.0/src/lib.rs:29:8
   |
29 |     P: IntoRawPtr + FromRawPtr,
   |        ---------- required by this bound in `atom::Atom`
   |
   = help: the trait `std::marker::Sized` is not implemented for `dyn Engine`
   = note: required because of the requirements on the impl of `atom::IntoRawPtr` for `std::sync::Arc<dyn Engine>`

error: aborting due to 2 previous errors; 2 warnings emitted

For more information about this error, try `rustc --explain E0277`.
error: could not compile `foo`.

To learn more, run the command again with --verbose.