bevy/crates/bevy_platform_support
Zachary Harrold 5241e09671
Upgrade to Rust Edition 2024 (#17967)
# Objective

- Fixes #17960

## Solution

- Followed the [edition upgrade
guide](https://doc.rust-lang.org/edition-guide/editions/transitioning-an-existing-project-to-a-new-edition.html)

## Testing

- CI

---

## Summary of Changes

### Documentation Indentation

When using lists in documentation, proper indentation is now linted for.
This means subsequent lines within the same list item must start at the
same indentation level as the item.

```rust
/* Valid */
/// - Item 1
///   Run-on sentence.
/// - Item 2
struct Foo;

/* Invalid */
/// - Item 1
///     Run-on sentence.
/// - Item 2
struct Foo;
```

### Implicit `!` to `()` Conversion

`!` (the never return type, returned by `panic!`, etc.) no longer
implicitly converts to `()`. This is particularly painful for systems
with `todo!` or `panic!` statements, as they will no longer be functions
returning `()` (or `Result<()>`), making them invalid systems for
functions like `add_systems`. The ideal fix would be to accept functions
returning `!` (or rather, _not_ returning), but this is blocked on the
[stabilisation of the `!` type
itself](https://doc.rust-lang.org/std/primitive.never.html), which is
not done.

The "simple" fix would be to add an explicit `-> ()` to system
signatures (e.g., `|| { todo!() }` becomes `|| -> () { todo!() }`).
However, this is _also_ banned, as there is an existing lint which (IMO,
incorrectly) marks this as an unnecessary annotation.

So, the "fix" (read: workaround) is to put these kinds of `|| -> ! { ...
}` closuers into variables and give the variable an explicit type (e.g.,
`fn()`).

```rust
// Valid
let system: fn() = || todo!("Not implemented yet!");
app.add_systems(..., system);

// Invalid
app.add_systems(..., || todo!("Not implemented yet!"));
```

### Temporary Variable Lifetimes

The order in which temporary variables are dropped has changed. The
simple fix here is _usually_ to just assign temporaries to a named
variable before use.

### `gen` is a keyword

We can no longer use the name `gen` as it is reserved for a future
generator syntax. This involved replacing uses of the name `gen` with
`r#gen` (the raw-identifier syntax).

### Formatting has changed

Use statements have had the order of imports changed, causing a
substantial +/-3,000 diff when applied. For now, I have opted-out of
this change by amending `rustfmt.toml`

```toml
style_edition = "2021"
```

This preserves the original formatting for now, reducing the size of
this PR. It would be a simple followup to update this to 2024 and run
`cargo fmt`.

### New `use<>` Opt-Out Syntax

Lifetimes are now implicitly included in RPIT types. There was a handful
of instances where it needed to be added to satisfy the borrow checker,
but there may be more cases where it _should_ be added to avoid
breakages in user code.

### `MyUnitStruct { .. }` is an invalid pattern

Previously, you could match against unit structs (and unit enum
variants) with a `{ .. }` destructuring. This is no longer valid.

### Pretty much every use of `ref` and `mut` are gone

Pattern binding has changed to the point where these terms are largely
unused now. They still serve a purpose, but it is far more niche now.

### `iter::repeat(...).take(...)` is bad

New lint recommends using the more explicit `iter::repeat_n(..., ...)`
instead.

## Migration Guide

The lifetimes of functions using return-position impl-trait (RPIT) are
likely _more_ conservative than they had been previously. If you
encounter lifetime issues with such a function, please create an issue
to investigate the addition of `+ use<...>`.

## Notes

- Check the individual commits for a clearer breakdown for what
_actually_ changed.

---------

Co-authored-by: François Mockers <francois.mockers@vleue.com>
2025-02-24 03:54:47 +00:00
..
src Improve ergonomics of platform_support's Instant (#17577) 2025-02-02 15:50:48 +00:00
Cargo.toml Upgrade to Rust Edition 2024 (#17967) 2025-02-24 03:54:47 +00:00
LICENSE-APACHE Cleanup publish process (#17728) 2025-02-09 17:46:19 +00:00
LICENSE-MIT Cleanup publish process (#17728) 2025-02-09 17:46:19 +00:00
README.md Create bevy_platform_support Crate (#17250) 2025-01-20 20:45:30 +00:00

Bevy Platform Support

License Crates.io Downloads Docs Discord

Rust is a fantastic multi-platform language with extensive support for modern targets through its standard library. However, some items within the standard library have alternatives that are better suited for Bevy and game engines in general. Additionally, to support embedded and other esoteric platforms, it's often necessary to shed reliance on std, making your crate no_std.

These needs are handled by this crate, bevy_platform_support. The goal of this crate is to provide alternatives and extensions to the Rust standard library which minimize friction when developing with and for Bevy across multiple platforms.

Getting Started

Like any dependency from crates.io, use cargo to add it to your Cargo.toml file:

cargo add bevy_platform_support

Now, instead of importing from std you can use bevy_platform_support for items it has alternative for. See the documentation for what items are available, and explanations for why you may want to use them.

no_std Support

By default, bevy_platform_support will activate the std feature, requiring access to the std crate for whichever platforms you're targeting. To use this crate on no_std platforms, disable default features:

bevy_platform_support = { version = "x.y.z", default-features = false }

Features

std (default)

Enables usage of the standard library. Note that where this crate has alternatives to the standard library that it considers better than what's provided, it will provide the alternative even when std is enabled. This is explicitly incompatible with no_std targets.

alloc (default)

Enables usage of the alloc crate. Note that this feature is automatically enabled when enabling std. This is compatible with most no_std targets, but not all.

portable-atomic

Switches to using portable-atomic as a backend for atomic types, such as Arc, AtomicU8, etc. You may need to enable this feature on platforms without full support for atomic types or certain operations, such as atomic CAS.

critical-section

Switches to using critical-section as a backend for synchronization. You may need to enable this feature on platforms with little to no support for atomic operations, and is often paired with the portable-atomic feature.