Why is the trait not implemented?

Question

I wanted to try the amethyst_physics library to make a game. (Duh) I followed to Example, but somhow I does not work:

use amethyst::GameDataBuilder;
use amethyst_physics::{PhysicsBundle};
use amethyst_nphysics::NPhysicsBackend;

fn main() -> amethyst::Result<()> {
    amethyst::start_logger(Default::default());

    let game_data = GameDataBuilder::default()
        .with_bundle(
            PhysicsBundle::<f32, NPhysicsBackend>::new()
        )
    ;
    Ok(())
}

Error:

the trait bound `amethyst_physics::PhysicsBundle<'_, '_, f32, amethyst_nphysics::NPhysicsBackend>: amethyst::amethyst_core::SystemBundle<'_, '_>` is not satisfied
the trait `amethyst::amethyst_core::SystemBundle<'_, '_>` is not implemented for `amethyst_physics::PhysicsBundle<'_, '_, f32, amethyst_nphysics::NPhysicsBackend>`

Here is the example.

What am I doing wrong?

Answer 1

This appears to be a bug. It compiles successfully using amethyst version 0.15.1 but not 0.15.3. A regression like this is not expected during a patch change.

amethyst uses amethyst_core version 0.15.3 (where SystemBundle is defined) but amethyst_physics uses amethyst_core version 0.10.1.

I've filed an issue on the amethyst repository.

---

Use this as a workaround:

amethyst = { version = ">=0.15.0, <0.15.3", features = ["empty"] }