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# Objective - Fixes #7680 - This is an updated for https://github.com/bevyengine/bevy/pull/8899 which had the same objective but fell a long way behind the latest changes ## Solution The traits `WorldQueryData : WorldQuery` and `WorldQueryFilter : WorldQuery` have been added and some of the types and functions from `WorldQuery` has been moved into them. `ReadOnlyWorldQuery` has been replaced with `ReadOnlyWorldQueryData`. `WorldQueryFilter` is safe (as long as `WorldQuery` is implemented safely). `WorldQueryData` is unsafe - safely implementing it requires that `Self::ReadOnly` is a readonly version of `Self` (this used to be a safety requirement of `WorldQuery`) The type parameters `Q` and `F` of `Query` must now implement `WorldQueryData` and `WorldQueryFilter` respectively. This makes it impossible to accidentally use a filter in the data position or vice versa which was something that could lead to bugs. ~~Compile failure tests have been added to check this.~~ It was previously sometimes useful to use `Option<With<T>>` in the data position. Use `Has<T>` instead in these cases. The `WorldQuery` derive macro has been split into separate derive macros for `WorldQueryData` and `WorldQueryFilter`. Previously it was possible to derive both `WorldQuery` for a struct that had a mixture of data and filter items. This would not work correctly in some cases but could be a useful pattern in others. *This is no longer possible.* --- ## Notes - The changes outside of `bevy_ecs` are all changing type parameters to the new types, updating the macro use, or replacing `Option<With<T>>` with `Has<T>`. - All `WorldQueryData` types always returned `true` for `IS_ARCHETYPAL` so I moved it to `WorldQueryFilter` and replaced all calls to it with `true`. That should be the only logic change outside of the macro generation code. - `Changed<T>` and `Added<T>` were being generated by a macro that I have expanded. Happy to revert that if desired. - The two derive macros share some functions for implementing `WorldQuery` but the tidiest way I could find to implement them was to give them a ton of arguments and ask clippy to ignore that. ## Changelog ### Changed - Split `WorldQuery` into `WorldQueryData` and `WorldQueryFilter` which now have separate derive macros. It is not possible to derive both for the same type. - `Query` now requires that the first type argument implements `WorldQueryData` and the second implements `WorldQueryFilter` ## Migration Guide - Update derives ```rust // old #[derive(WorldQuery)] #[world_query(mutable, derive(Debug))] struct CustomQuery { entity: Entity, a: &'static mut ComponentA } #[derive(WorldQuery)] struct QueryFilter { _c: With<ComponentC> } // new #[derive(WorldQueryData)] #[world_query_data(mutable, derive(Debug))] struct CustomQuery { entity: Entity, a: &'static mut ComponentA, } #[derive(WorldQueryFilter)] struct QueryFilter { _c: With<ComponentC> } ``` - Replace `Option<With<T>>` with `Has<T>` ```rust /// old fn my_system(query: Query<(Entity, Option<With<ComponentA>>)>) { for (entity, has_a_option) in query.iter(){ let has_a:bool = has_a_option.is_some(); //todo!() } } /// new fn my_system(query: Query<(Entity, Has<ComponentA>)>) { for (entity, has_a) in query.iter(){ //todo!() } } ``` - Fix queries which had filters in the data position or vice versa. ```rust // old fn my_system(query: Query<(Entity, With<ComponentA>)>) { for (entity, _) in query.iter(){ //todo!() } } // new fn my_system(query: Query<Entity, With<ComponentA>>) { for entity in query.iter(){ //todo!() } } // old fn my_system(query: Query<AnyOf<(&ComponentA, With<ComponentB>)>>) { for (entity, _) in query.iter(){ //todo!() } } // new fn my_system(query: Query<Option<&ComponentA>, Or<(With<ComponentA>, With<ComponentB>)>>) { for entity in query.iter(){ //todo!() } } ``` --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> |
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Compile fail tests for bevy_ecs
This crate is separate from bevy_ecs
and not part of the Bevy workspace in order to not fail crater
tests for Bevy. The tests assert on the exact compiler errors and can easily fail for new Rust versions due to updated compiler errors (e.g. changes in spans).
The CI
workflow executes these tests on the stable rust toolchain (see tools/ci).