This gets rid of multiple unsafe blocks that we had to maintain ourselves, and instead depends on library that's commonly used and supported by the ecosystem. We also get support for glam types for free.
There is still some things to clear up with the `Bytes` trait, but that is a bit more substantial change and can be done separately. Also there are already separate efforts to use `crevice` crate, so I've just added that as a TODO.
After running `bevy_core` through `miri`, errors were reported surrounding incorrect memory accesses within the `bytes` test suit.
Specifically:
```
test bytes::tests::test_array_round_trip ... error: Undefined Behavior: accessing memory with alignment 1, but alignment 4 is required
--> crates/bevy_core/src/bytes.rs:55:13
|
55 | (*ptr).clone()
| ^^^^^^ accessing memory with alignment 1, but alignment 4 is required
|
```
and
```
test bytes::tests::test_vec_bytes_round_trip ... error: Undefined Behavior: accessing memory with alignment 2, but alignment 4 is required
--> /home/nward/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/slice/raw.rs:95:14
|
95 | unsafe { &*ptr::slice_from_raw_parts(data, len) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ accessing memory with alignment 2, but alignment 4 is required
|
```
Solution:
The solution is to use `slice::align_to` method to ensure correct alignment.
Implements `Byteable` and `RenderResource` for any array containing `Byteable` elements. This allows `RenderResources` to be implemented on structs with arbitrarily-sized arrays, among other things:
```rust
#[derive(RenderResources, TypeUuid)]
#[uuid = "2733ff34-8f95-459f-bf04-3274e686ac5f"]
struct Foo {
buffer: [i32; 256],
}
```
