impl Eq/PartialEq for MeshMaterial{2|3}d

[jnhyatt]

Objective

Eq/PartialEq are currently implemented for MeshMaterial{2|3}d only through the derive macro. Since we don't have perfect derive yet, the impls are only present for M: Eq and M: PartialEq. On the other hand, I want to be able to compare material components for my toy reactivity project.

Solution

Switch to manual Eq/PartialEq impl.

Testing

Boy I hope this didn't break anything!

[hukasu]

why exactly does the derive not works for M that are not PartialEq or Eq?

and what about adding PartialEq and Eq to the required traits of Material2d and Material3d?

pub trait Material2d:
    Sized
    + AsBindGroup
    + Asset
    + Clone
    + PartialEq
    + Eq;

[hukasu]

and for testing you could run cargo run -p ci

add CARGO_BUILD_JOBS and RUST_TEST_THREADS to the env to prevent OOM

[alice-i-cecile]

why exactly does the derive not works for M that are not PartialEq or Eq?

This is a standard Rust problem: "perfect derive" is the name of the solution for this. The derive macros assume that the internal types must also be compared, but when you're using things like PhantomData that isn't the case.

and what about adding PartialEq and Eq to the required traits of Material2d and Material3d?

Generally, we should try to avoid adding bounds without a good reason, and prefer to add them at methods etc. It's less verbose to work with and more flexible.

[jnhyatt]

@hukasu There shouldn't be any behavior changes. Tests run before merging anyway, that's why I didn't bother running tests locally.