# Objective
The [Stageless RFC](https://github.com/bevyengine/rfcs/pull/45) involves allowing exclusive systems to be referenced and ordered relative to parallel systems. We've agreed that unifying systems under `System` is the right move.
This is an alternative to #4166 (see rationale in the comments I left there). Note that this builds on the learnings established there (and borrows some patterns).
## Solution
This unifies parallel and exclusive systems under the shared `System` trait, removing the old `ExclusiveSystem` trait / impls. This is accomplished by adding a new `ExclusiveFunctionSystem` impl similar to `FunctionSystem`. It is backed by `ExclusiveSystemParam`, which is similar to `SystemParam`. There is a new flattened out SystemContainer api (which cuts out a lot of trait and type complexity).
This means you can remove all cases of `exclusive_system()`:
```rust
// before
commands.add_system(some_system.exclusive_system());
// after
commands.add_system(some_system);
```
I've also implemented `ExclusiveSystemParam` for `&mut QueryState` and `&mut SystemState`, which makes this possible in exclusive systems:
```rust
fn some_exclusive_system(
world: &mut World,
transforms: &mut QueryState<&Transform>,
state: &mut SystemState<(Res<Time>, Query<&Player>)>,
) {
for transform in transforms.iter(world) {
println!("{transform:?}");
}
let (time, players) = state.get(world);
for player in players.iter() {
println!("{player:?}");
}
}
```
Note that "exclusive function systems" assume `&mut World` is present (and the first param). I think this is a fair assumption, given that the presence of `&mut World` is what defines the need for an exclusive system.
I added some targeted SystemParam `static` constraints, which removed the need for this:
``` rust
fn some_exclusive_system(state: &mut SystemState<(Res<'static, Time>, Query<&'static Player>)>) {}
```
## Related
- #2923
- #3001
- #3946
## Changelog
- `ExclusiveSystem` trait (and implementations) has been removed in favor of sharing the `System` trait.
- `ExclusiveFunctionSystem` and `ExclusiveSystemParam` were added, enabling flexible exclusive function systems
- `&mut SystemState` and `&mut QueryState` now implement `ExclusiveSystemParam`
- Exclusive and parallel System configuration is now done via a unified `SystemDescriptor`, `IntoSystemDescriptor`, and `SystemContainer` api.
## Migration Guide
Calling `.exclusive_system()` is no longer required (or supported) for converting exclusive system functions to exclusive systems:
```rust
// Old (0.8)
app.add_system(some_exclusive_system.exclusive_system());
// New (0.9)
app.add_system(some_exclusive_system);
```
Converting "normal" parallel systems to exclusive systems is done by calling the exclusive ordering apis:
```rust
// Old (0.8)
app.add_system(some_system.exclusive_system().at_end());
// New (0.9)
app.add_system(some_system.at_end());
```
Query state in exclusive systems can now be cached via ExclusiveSystemParams, which should be preferred for clarity and performance reasons:
```rust
// Old (0.8)
fn some_system(world: &mut World) {
let mut transforms = world.query::<&Transform>();
for transform in transforms.iter(world) {
}
}
// New (0.9)
fn some_system(world: &mut World, transforms: &mut QueryState<&Transform>) {
for transform in transforms.iter(world) {
}
}
```
# Objective
- Update ron to 0.8.0
- Fix breaking changes
- Closes#5862
## Solution
- Removed now non-existing method call (behavior is now the same without it)
*This PR description is an edited copy of #5007, written by @alice-i-cecile.*
# Objective
Follow-up to https://github.com/bevyengine/bevy/pull/2254. The `Resource` trait currently has a blanket implementation for all types that meet its bounds.
While ergonomic, this results in several drawbacks:
* it is possible to make confusing, silent mistakes such as inserting a function pointer (Foo) rather than a value (Foo::Bar) as a resource
* it is challenging to discover if a type is intended to be used as a resource
* we cannot later add customization options (see the [RFC](https://github.com/bevyengine/rfcs/blob/main/rfcs/27-derive-component.md) for the equivalent choice for Component).
* dependencies can use the same Rust type as a resource in invisibly conflicting ways
* raw Rust types used as resources cannot preserve privacy appropriately, as anyone able to access that type can read and write to internal values
* we cannot capture a definitive list of possible resources to display to users in an editor
## Notes to reviewers
* Review this commit-by-commit; there's effectively no back-tracking and there's a lot of churn in some of these commits.
*ira: My commits are not as well organized :')*
* I've relaxed the bound on Local to Send + Sync + 'static: I don't think these concerns apply there, so this can keep things simple. Storing e.g. a u32 in a Local is fine, because there's a variable name attached explaining what it does.
* I think this is a bad place for the Resource trait to live, but I've left it in place to make reviewing easier. IMO that's best tackled with https://github.com/bevyengine/bevy/issues/4981.
## Changelog
`Resource` is no longer automatically implemented for all matching types. Instead, use the new `#[derive(Resource)]` macro.
## Migration Guide
Add `#[derive(Resource)]` to all types you are using as a resource.
If you are using a third party type as a resource, wrap it in a tuple struct to bypass orphan rules. Consider deriving `Deref` and `DerefMut` to improve ergonomics.
`ClearColor` no longer implements `Component`. Using `ClearColor` as a component in 0.8 did nothing.
Use the `ClearColorConfig` in the `Camera3d` and `Camera2d` components instead.
Co-authored-by: Alice <alice.i.cecile@gmail.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: devil-ira <justthecooldude@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Some generic types like `Option<T>`, `Vec<T>` and `HashMap<K, V>` implement `Reflect` when where their generic types `T`/`K`/`V` implement `Serialize + for<'de> Deserialize<'de>`.
This is so that in their `GetTypeRegistration` impl they can insert the `ReflectSerialize` and `ReflectDeserialize` type data structs.
This has the annoying side effect that if your struct contains a `Option<NonSerdeStruct>` you won't be able to derive reflect (https://github.com/bevyengine/bevy/issues/4054).
## Solution
- remove the `Serialize + Deserialize` bounds on wrapper types
- this means that `ReflectSerialize` and `ReflectDeserialize` will no longer be inserted even for `.register::<Option<DoesImplSerde>>()`
- add `register_type_data<T, D>` shorthand for `registry.get_mut(T).insert(D::from_type<T>())`
- require users to register their specific generic types **and the serde types** separately like
```rust
.register_type::<Option<String>>()
.register_type_data::<Option<String>, ReflectSerialize>()
.register_type_data::<Option<String>, ReflectDeserialize>()
```
I believe this is the best we can do for extensibility and convenience without specialization.
## Changelog
- `.register_type` for generic types like `Option<T>`, `Vec<T>`, `HashMap<K, V>` will no longer insert `ReflectSerialize` and `ReflectDeserialize` type data. Instead you need to register it separately for concrete generic types like so:
```rust
.register_type::<Option<String>>()
.register_type_data::<Option<String>, ReflectSerialize>()
.register_type_data::<Option<String>, ReflectDeserialize>()
```
TODO: more docs and tweaks to the scene example to demonstrate registering generic types.
# Objective
I noticed while working on #5366 that the documentation for label types wasn't working correctly. Having experimented with this for a few weeks, I believe that generating docs in macros is more effort than it's worth.
## Solution
Add more boilerplate, copy-paste and edit the docs across types. This also lets us add custom doctests for specific types. Also, we don't need `concat_idents` as a dependency anymore.
# Objective
- Closes#4954
- Reduce the complexity of the `{System, App, *}Label` APIs.
## Solution
For the sake of brevity I will only refer to `SystemLabel`, but everything applies to all of the other label types as well.
- Add `SystemLabelId`, a lightweight, `copy` struct.
- Convert custom types into `SystemLabelId` using the trait `SystemLabel`.
## Changelog
- String literals implement `SystemLabel` for now, but this should be changed with #4409 .
## Migration Guide
- Any previous use of `Box<dyn SystemLabel>` should be replaced with `SystemLabelId`.
- `AsSystemLabel` trait has been modified.
- No more output generics.
- Method `as_system_label` now returns `SystemLabelId`, removing an unnecessary level of indirection.
- If you *need* a label that is determined at runtime, you can use `Box::leak`. Not recommended.
## Questions for later
* Should we generate a `Debug` impl along with `#[derive(*Label)]`?
* Should we rename `as_str()`?
* Should we remove the extra derives (such as `Hash`) from builtin `*Label` types?
* Should we automatically derive types like `Clone, Copy, PartialEq, Eq`?
* More-ergonomic comparisons between `Label` and `LabelId`.
* Move `Dyn{Eq, Hash,Clone}` somewhere else.
* Some API to make interning dynamic labels easier.
* Optimize string representation
* Empty string for unit structs -- no debug info but faster comparisons
* Don't show enum types -- same tradeoffs as asbove.
# Objective
- I think our codebase is hit badly by rust-lang/rust-analyzer#11410
- None of our uses of cyclic dependencies are remotely necessary
- Note that these are false positives in rust-analyzer, however it's probably easier for us to work around this
- Note also that I haven't confirmed that this is causing rust-analyzer to not work very well, but it's not a bad guess.
## Solution
- Remove our cyclic dependencies
- Import the trick from #2851 for no-op plugin groups.
Right now, a direct reference to the target TaskPool is required to launch tasks on the pools, despite the three newtyped pools (AsyncComputeTaskPool, ComputeTaskPool, and IoTaskPool) effectively acting as global instances. The need to pass a TaskPool reference adds notable friction to spawning subtasks within existing tasks. Possible use cases for this may include chaining tasks within the same pool like spawning separate send/receive I/O tasks after waiting on a network connection to be established, or allowing cross-pool dependent tasks like starting dependent multi-frame computations following a long I/O load.
Other task execution runtimes provide static access to spawning tasks (i.e. `tokio::spawn`), which is notably easier to use than the reference passing required by `bevy_tasks` right now.
This PR makes does the following:
* Adds `*TaskPool::init` which initializes a `OnceCell`'ed with a provided TaskPool. Failing if the pool has already been initialized.
* Adds `*TaskPool::get` which fetches the initialized global pool of the respective type or panics. This generally should not be an issue in normal Bevy use, as the pools are initialized before they are accessed.
* Updated default task pool initialization to either pull the global handles and save them as resources, or if they are already initialized, pull the a cloned global handle as the resource.
This should make it notably easier to build more complex task hierarchies for dependent tasks. It should also make writing bevy-adjacent, but not strictly bevy-only plugin crates easier, as the global pools ensure it's all running on the same threads.
One alternative considered is keeping a thread-local reference to the pool for all threads in each pool to enable the same `tokio::spawn` interface. This would spawn tasks on the same pool that a task is currently running in. However this potentially leads to potential footgun situations where long running blocking tasks run on `ComputeTaskPool`.
# Objective
- Run examples in WASM in CI
- Fix#4817
## Solution
- on feature `bevy_ci_testing`
- add an extra log message before exiting
- when building for wasm, read CI config file at compile time
- add a simple [playwright](https://playwright.dev) test script that opens the browser then waits for the success log, and takes a screenshot
- add a CI job that runs the playwright test for Chromium and Firefox on one example (lighting) and save the screenshots
- Firefox screenshot is good (with some clusters visible)
- Chromium screenshot is gray, I don't know why but it's logging `GPU stall due to ReadPixels`
- Webkit is not enabled for now, to revisit once https://bugs.webkit.org/show_bug.cgi?id=234926 is fixed or worked around
- the CI job only runs on bors validation
example run: https://github.com/mockersf/bevy/actions/runs/2361673465. The screenshots can be downloaded
# Objective
Fixes#4791. `ParallelExecutor` inserts a default `CompteTaskPool` if there isn't one stored as a resource, including when it runs on a different world. When spawning the render sub-app, the main world's `ComputeTaskPool` is not cloned and inserted into the render app's, which causes a second `ComputeTaskPool` with the default configuration to be spawned. This results in an excess number of threads being spawned.
## Solution
Copy the task pools from the main world to the subapps upon creating them.
## Alternative
An alternative to this would be to make the task pools global, as seen in #2250 or bevyengine/rfcs#54.
# Objective
- Make bevy_app's optional bevy_reflect dependency actually optional
- Because bevy_ecs has a default dependency on bevy_reflect, bevy_app includes bevy_reflect transitively even with default-features=false, despite the optional dependency indicating that it was intended to be able to leave out bevy_reflect.
## Solution
- Make bevy_app not enable bevy_ecs's default features, and then use [the `dep:` syntax](https://doc.rust-lang.org/cargo/reference/features.html#optional-dependencies) introduced in 1.60 to make the default bevy_reflect feature enable bevy_ecs's bevy_reflect feature/dependency.
---
## Changelog
- bevy_app no longer enables bevy_ecs's `bevy_reflect` feature when included without its own `bevy_reflect` feature (which is on by default).
# Objective
- Remove `Resource` binding on events, introduce a new `Event` trait
- Ensure event iterators are `ExactSizeIterator`
## Solution
- Builds on #2382 and #2969
## Changelog
- Events<T>, EventWriter<T>, EventReader<T> and so on now require that the underlying type is Event, rather than Resource. Both of these are trivial supertraits of Send + Sync + 'static with universal blanket implementations: this change is currently purely cosmetic.
- Event reader iterators now implement ExactSizeIterator
In a `PluginGroupBuilder`, when adding a plugin that was already in the group (potentially disabled), it was then added twice to the app builder when calling `finish`. As the plugin is kept in an `HashMap`, it is not possible to have the same plugins twice with different configuration.
This PR updates the order of the plugin group so that each plugin is present only once.
Co-authored-by: François <8672791+mockersf@users.noreply.github.com>
# Objective
- `RunOnce` was a manual `System` implementation.
- Adding run criteria to stages was yet to be systemyoten
## Solution
- Make it a normal function
- yeet
## Changelog
- Replaced `RunOnce` with `ShouldRun::once`
## Migration guide
The run criterion `RunOnce`, which would make the controlled systems run only once, has been replaced with a new run criterion function `ShouldRun::once`. Replace all instances of `RunOnce` with `ShouldRun::once`.
# Objective
- Clean up duplicate code in the add_before/add_after functions in PluginGroupBuilder.
## Solution
- moved index retrieval code to a private function index_of() for the PluginGroupBuilder.
- change is just tidying up. No real change to functionality.
# Objective
The `bevy_app` crate has a lot of inconsistencies in the documentation (formatting, spelling, phrasing, consistency).
## Solution
Make it more consistent.
# Objective
As described in #4257, registering an Event twice would cause some systems to miss events on some starts, since the event buffer is cleared + swapped multiple times.
Fixes#4257
## Solution
A simple check whether the event is already registered is added, making adding an Event a second time a no-op.
Tracing added support for "inline span entering", which cuts down on a lot of complexity:
```rust
let span = info_span!("my_span").entered();
```
This adapts our code to use this pattern where possible, and updates our docs to recommend it.
This produces equivalent tracing behavior. Here is a side by side profile of "before" and "after" these changes.
# Objective
- In the large majority of cases, users were calling `.unwrap()` immediately after `.get_resource`.
- Attempting to add more helpful error messages here resulted in endless manual boilerplate (see #3899 and the linked PRs).
## Solution
- Add an infallible variant named `.resource` and so on.
- Use these infallible variants over `.get_resource().unwrap()` across the code base.
## Notes
I did not provide equivalent methods on `WorldCell`, in favor of removing it entirely in #3939.
## Migration Guide
Infallible variants of `.get_resource` have been added that implicitly panic, rather than needing to be unwrapped.
Replace `world.get_resource::<Foo>().unwrap()` with `world.resource::<Foo>()`.
## Impact
- `.unwrap` search results before: 1084
- `.unwrap` search results after: 942
- internal `unwrap_or_else` calls added: 4
- trivial unwrap calls removed from tests and code: 146
- uses of the new `try_get_resource` API: 11
- percentage of the time the unwrapping API was used internally: 93%
What is says on the tin.
This has got more to do with making `clippy` slightly more *quiet* than it does with changing anything that might greatly impact readability or performance.
that said, deriving `Default` for a couple of structs is a nice easy win
# Objective
- Fixes#3078
- Fixes#1397
## Solution
- Implement Commands::init_resource.
- Also implement for World, for consistency and to simplify internal structure.
- While we're here, clean up some of the docs for Command and World resource modification.
# Objective
- `CoreStage::Startup` is unique in the `CoreStage` enum, in that it represents a `Schedule` and not a `SystemStage`.
- This can lead to confusion about how `CoreStage::Startup` and the `StartupStage` enum are related.
- Beginners sometimes try `.add_system_to_stage(CoreStage::Startup, setup.system())` instead of `.add_startup_system(setup.system())`, which causes a Panic:
```
thread 'main' panicked at 'Stage 'Startup' does not exist or is not a SystemStage', crates\bevy_ecs\src\schedule\mod.rs:153:13
stack backtrace:
0: std::panicking::begin_panic_handler
at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b\/library\std\src\panicking.rs:493
1: std::panicking::begin_panic_fmt
at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b\/library\std\src\panicking.rs:435
2: bevy_ecs::schedule::{{impl}}::add_system_to_stage::stage_not_found
at .\crates\bevy_ecs\src\schedule\mod.rs:153
3: bevy_ecs::schedule::{{impl}}::add_system_to_stage::{{closure}}<tuple<bevy_ecs::system::function_system::IsFunctionSystem, tuple<bevy_ecs::system::commands::Commands, bevy_ecs::change_detection::ResMut<bevy_asset::assets::Assets<bevy_render::mesh::mesh::Me
at .\crates\bevy_ecs\src\schedule\mod.rs:161
4: core::option::Option<mut bevy_ecs::schedule::stage::SystemStage*>::unwrap_or_else<mut bevy_ecs::schedule::stage::SystemStage*,closure-0>
at C:\Users\scher\.rustup\toolchains\stable-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\option.rs:427
5: bevy_ecs::schedule::Schedule::add_system_to_stage<tuple<bevy_ecs::system::function_system::IsFunctionSystem, tuple<bevy_ecs::system::commands::Commands, bevy_ecs::change_detection::ResMut<bevy_asset::assets::Assets<bevy_render::mesh::mesh::Mesh>>, bevy_ec
at .\crates\bevy_ecs\src\schedule\mod.rs:159
6: bevy_app::app_builder::AppBuilder::add_system_to_stage<tuple<bevy_ecs::system::function_system::IsFunctionSystem, tuple<bevy_ecs::system::commands::Commands, bevy_ecs::change_detection::ResMut<bevy_asset::assets::Assets<bevy_render::mesh::mesh::Mesh>>, be
at .\crates\bevy_app\src\app_builder.rs:196
7: 3d_scene::main
at .\examples\3d\3d_scene.rs:4
8: core::ops::function::FnOnce::call_once<fn(),tuple<>>
at C:\Users\scher\.rustup\toolchains\stable-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\ops\function.rs:227
```
## Solution
- Replace the `CoreStage::Startup` Label with the new `StartupSchedule` unit type.
Resolves#2229
# Objective
Fixes#3250
## Solution
Since this panic occurs in bevy_ecs, and StartupStage is part of
bevy_app, we really only have access to the Debug string of the
`stage_label` parameter. This led me to the hacky solution of
comparing the debug output of the label the user provides with the known
variants of StartupStage.
An alternative would be to do this error handling further up in
bevy_app, where we can access StartupStage's typeid, but I don't think
it is worth having a panic in 2 places (_ecs, and _app).
# Objective
When using empty events, it can feel redundant to have to specify the type of the event when sending it.
## Solution
Add a new `fire()` function that sends the default value of the event. This requires that the event derives Default.
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
Documentation added to:
- `App::add_sub_app` (
- `App::update` (mentions that sub apps are updated here)
### Future work
- An example for `add_sub_app` would be good, but I wasn't able to come up with a simple one.
- Since `SubApp` is private, maybe the concept of sub applications could be introduced in the `App` struct-level documentation.
# Objective
CI should check for missing backticks in doc comments.
Fixes#3435
## Solution
`clippy` has a lint for this: `doc_markdown`. This enables that lint in the CI script.
Of course, enabling this lint in CI causes a bunch of lint errors, so I've gone through and fixed all of them. This was a huge edit that touched a ton of files, so I split the PR up by crate.
When all of the following are merged, the CI should pass and this can be merged.
+ [x] #3467
+ [x] #3468
+ [x] #3470
+ [x] #3469
+ [x] #3471
+ [x] #3472
+ [x] #3473
+ [x] #3474
+ [x] #3475
+ [x] #3476
+ [x] #3477
+ [x] #3478
+ [x] #3479
+ [x] #3480
+ [x] #3481
+ [x] #3482
+ [x] #3483
+ [x] #3484
+ [x] #3485
+ [x] #3486
#3457 adds the `doc_markdown` clippy lint, which checks doc comments to make sure code identifiers are escaped with backticks. This causes a lot of lint errors, so this is one of a number of PR's that will fix those lint errors one crate at a time.
This PR fixes lints in the `bevy_app` crate.
# Objective
- there are a few new versions for `ron`, `winit`, `ndk`, `raw-window-handle`
- `cargo-deny` is failing due to new security issues / duplicated dependencies
## Solution
- Update our dependencies
- Note all new security issues, with which of Bevy direct dependency it comes from
- Update duplicate crate list, with which of Bevy direct dependency it comes from
`notify` is not updated here as it's in #2993
Objective
During work on #3009 I've found that not all jobs use actions-rs, and therefore, an previous version of Rust is used for them. So while compilation and other stuff can pass, checking markup and Android build may fail with compilation errors.
Solution
This PR adds `action-rs` for any job running cargo, and updates the edition to 2021.
This implements the most minimal variant of #1843 - a derive for marker trait. This is a prerequisite to more complicated features like statically defined storage type or opt-out component reflection.
In order to make component struct's purpose explicit and avoid misuse, it must be annotated with `#[derive(Component)]` (manual impl is discouraged for compatibility). Right now this is just a marker trait, but in the future it might be expanded. Making this change early allows us to make further changes later without breaking backward compatibility for derive macro users.
This already prevents a lot of issues, like using bundles in `insert` calls. Primitive types are no longer valid components as well. This can be easily worked around by adding newtype wrappers and deriving `Component` for them.
One funny example of prevented bad code (from our own tests) is when an newtype struct or enum variant is used. Previously, it was possible to write `insert(Newtype)` instead of `insert(Newtype(value))`. That code compiled, because function pointers (in this case newtype struct constructor) implement `Send + Sync + 'static`, so we allowed them to be used as components. This is no longer the case and such invalid code will trigger a compile error.
Co-authored-by: = <=>
Co-authored-by: TheRawMeatball <therawmeatball@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
## Objective
The upcoming Bevy Book makes many references to the API documentation of bevy.
Most references belong to the first two chapters of the Bevy Book:
- bevyengine/bevy-website#176
- bevyengine/bevy-website#182
This PR attempts to improve the documentation of `bevy_ecs` and `bevy_app` in order to help readers of the Book who want to delve deeper into technical details.
## Solution
- Add crate and level module documentation
- Document the most important items (basically those included in the preludes), with the following style, where applicable:
- **Summary.** Short description of the item.
- **Second paragraph.** Detailed description of the item, without going too much in the implementation.
- **Code example(s).**
- **Safety or panic notes.**
## Collaboration
Any kind of collaboration is welcome, especially corrections, wording, new ideas and guidelines on where the focus should be put in.
---
### Related issues
- Fixes#2246
