Default Component Impl

[jmeggitt]

Description

Add a feature auto-component (or maybe specialization) that uses the nightly feature specialization to make everything a component. I noticed there already is a nightly feature, but I wanted to keep them separate for this example.

#![cfg_attr(feature = "auto-component", feature(specialization))]

pub trait Component: Any + Sized {
    /// Associated storage type for this component.
     type Storage: UnprotectedStorage<Self> + Any + Send + Sync;
}

#[cfg(feature = "auto-component")]
default impl<T> Component for T {
    type Storage = BTreeStorage<Self>;
}

Motivation

Often I find myself writing annoying wrappers for structs/enums in other crates. Then afterwards it
takes additional steps to get to the data I care about. This is not a perfect solution, but it does help with quick tests, and small projects where memory efficiency and performance can be overlooked for ease of use.

Drawbacks

• This feature requires nightly to work.
• It encourages not explicitly implementing Component for new components.

If this is something that other people want, I can write a quick pull request for it.