3aed85a88b
4 Commits
| Author | SHA1 | Message | Date | |
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Zachary Harrold
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d70595b667
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Add core and alloc over std Lints (#15281)
# Objective - Fixes #6370 - Closes #6581 ## Solution - Added the following lints to the workspace: - `std_instead_of_core` - `std_instead_of_alloc` - `alloc_instead_of_core` - Used `cargo +nightly fmt` with [item level use formatting](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#Item%5C%3A) to split all `use` statements into single items. - Used `cargo clippy --workspace --all-targets --all-features --fix --allow-dirty` to _attempt_ to resolve the new linting issues, and intervened where the lint was unable to resolve the issue automatically (usually due to needing an `extern crate alloc;` statement in a crate root). - Manually removed certain uses of `std` where negative feature gating prevented `--all-features` from finding the offending uses. - Used `cargo +nightly fmt` with [crate level use formatting](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#Crate%5C%3A) to re-merge all `use` statements matching Bevy's previous styling. - Manually fixed cases where the `fmt` tool could not re-merge `use` statements due to conditional compilation attributes. ## Testing - Ran CI locally ## Migration Guide The MSRV is now 1.81. Please update to this version or higher. ## Notes - This is a _massive_ change to try and push through, which is why I've outlined the semi-automatic steps I used to create this PR, in case this fails and someone else tries again in the future. - Making this change has no impact on user code, but does mean Bevy contributors will be warned to use `core` and `alloc` instead of `std` where possible. - This lint is a critical first step towards investigating `no_std` options for Bevy. --------- Co-authored-by: François Mockers <francois.mockers@vleue.com> |
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Gino Valente
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b7d68873ec
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bevy_derive: Fix #[deref] breaking other attributes (#9551)
# Objective Fixes #9550 ## Solution Removes a check that asserts that _all_ attribute metas are path-only, rather than just the `#[deref]` attribute itself. --- ## Changelog - Fixes an issue where deriving `Deref` with `#[deref]` on a field causes other attributes to sometimes result in a compile error --------- Co-authored-by: François <mockersf@gmail.com> |
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Gino Valente
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56686a8962
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bevy_derive: Add #[deref] attribute (#8552)
# Objective Bevy code tends to make heavy use of the [newtype]( https://doc.rust-lang.org/rust-by-example/generics/new_types.html) pattern, which is why we have a dedicated derive for [`Deref`](https://doc.rust-lang.org/std/ops/trait.Deref.html) and [`DerefMut`](https://doc.rust-lang.org/std/ops/trait.DerefMut.html). This derive works for any struct with a single field: ```rust #[derive(Component, Deref, DerefMut)] struct MyNewtype(usize); ``` One reason for the single-field limitation is to prevent confusion and footguns related that would arise from allowing multi-field structs: <table align="center"> <tr> <th colspan="2"> Similar structs, different derefs </th> </tr> <tr> <td> ```rust #[derive(Deref, DerefMut)] struct MyStruct { foo: usize, // <- Derefs usize bar: String, } ``` </td> <td> ```rust #[derive(Deref, DerefMut)] struct MyStruct { bar: String, // <- Derefs String foo: usize, } ``` </td> </tr> <tr> <th colspan="2"> Why `.1`? </th> </tr> <tr> <td colspan="2"> ```rust #[derive(Deref, DerefMut)] struct MyStruct(Vec<usize>, Vec<f32>); let mut foo = MyStruct(vec![123], vec![1.23]); // Why can we skip the `.0` here? foo.push(456); // But not here? foo.1.push(4.56); ``` </td> </tr> </table> However, there are certainly cases where it's useful to allow for structs with multiple fields. Such as for structs with one "real" field and one `PhantomData` to allow for generics: ```rust #[derive(Deref, DerefMut)] struct MyStruct<T>( // We want use this field for the `Deref`/`DerefMut` impls String, // But we need this field so that we can make this struct generic PhantomData<T> ); // ERROR: Deref can only be derived for structs with a single field // ERROR: DerefMut can only be derived for structs with a single field ``` Additionally, the possible confusion and footguns are mainly an issue for newer Rust/Bevy users. Those familiar with `Deref` and `DerefMut` understand what adding the derive really means and can anticipate its behavior. ## Solution Allow users to opt into multi-field `Deref`/`DerefMut` derives using a `#[deref]` attribute: ```rust #[derive(Deref, DerefMut)] struct MyStruct<T>( // Use this field for the `Deref`/`DerefMut` impls #[deref] String, // We can freely include any other field without a compile error PhantomData<T> ); ``` This prevents the footgun pointed out in the first issue described in the previous section, but it still leaves the possible confusion surrounding `.0`-vs-`.#`. However, the idea is that by making this behavior explicit with an attribute, users will be more aware of it and can adapt appropriately. --- ## Changelog - Added `#[deref]` attribute to `Deref` and `DerefMut` derives |
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MrGVSV
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f16768d868 |
bevy_derive: Add derives for Deref and DerefMut (#4328)
# Objective A common pattern in Rust is the [newtype](https://doc.rust-lang.org/rust-by-example/generics/new_types.html). This is an especially useful pattern in Bevy as it allows us to give common/foreign types different semantics (such as allowing it to implement `Component` or `FromWorld`) or to simply treat them as a "new type" (clever). For example, it allows us to wrap a common `Vec<String>` and do things like: ```rust #[derive(Component)] struct Items(Vec<String>); fn give_sword(query: Query<&mut Items>) { query.single_mut().0.push(String::from("Flaming Poisoning Raging Sword of Doom")); } ``` > We could then define another struct that wraps `Vec<String>` without anything clashing in the query. However, one of the worst parts of this pattern is the ugly `.0` we have to write in order to access the type we actually care about. This is why people often implement `Deref` and `DerefMut` in order to get around this. Since it's such a common pattern, especially for Bevy, it makes sense to add a derive macro to automatically add those implementations. ## Solution Added a derive macro for `Deref` and another for `DerefMut` (both exported into the prelude). This works on all structs (including tuple structs) as long as they only contain a single field: ```rust #[derive(Deref)] struct Foo(String); #[derive(Deref, DerefMut)] struct Bar { name: String, } ``` This allows us to then remove that pesky `.0`: ```rust #[derive(Component, Deref, DerefMut)] struct Items(Vec<String>); fn give_sword(query: Query<&mut Items>) { query.single_mut().push(String::from("Flaming Poisoning Raging Sword of Doom")); } ``` ### Alternatives There are other alternatives to this such as by using the [`derive_more`](https://crates.io/crates/derive_more) crate. However, it doesn't seem like we need an entire crate just yet since we only need `Deref` and `DerefMut` (for now). ### Considerations One thing to consider is that the Rust std library recommends _not_ using `Deref` and `DerefMut` for things like this: "`Deref` should only be implemented for smart pointers to avoid confusion" ([reference](https://doc.rust-lang.org/std/ops/trait.Deref.html)). Personally, I believe it makes sense to use it in the way described above, but others may disagree. ### Additional Context Discord: https://discord.com/channels/691052431525675048/692572690833473578/956648422163746827 (controversiality discussed [here](https://discord.com/channels/691052431525675048/692572690833473578/956711911481835630)) --- ## Changelog - Add `Deref` derive macro (exported to prelude) - Add `DerefMut` derive macro (exported to prelude) - Updated most newtypes in examples to use one or both derives Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com> |