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# Objective Fix unsoundness introduced by #15858. `QueryLens::query()` would hand out a `Query` with the full `'w` lifetime, and the new `_inner` methods would let the results outlive the `Query`. This could be used to create aliasing mutable references, like ```rust fn bad<'w>(mut lens: QueryLens<'w, EntityMut>, entity: Entity) { let one: EntityMut<'w> = lens.query().get_inner(entity).unwrap(); let two: EntityMut<'w> = lens.query().get_inner(entity).unwrap(); assert!(one.entity() == two.entity()); } ``` Fixes #17693 ## Solution Restrict the `'world` lifetime in the `Query` returned by `QueryLens::query()` to `'_`, the lifetime of the borrow of the `QueryLens`. The model here is that `Query<'w, 's, D, F>` and `QueryLens<'w, D, F>` have permission to access their components for the lifetime `'w`. So going from `&'a mut QueryLens<'w>` to `Query<'w, 'a>` would borrow the permission only for the `'a` lifetime, but incorrectly give it out for the full `'w` lifetime. To handle any cases where users were calling `get_inner()` or `iter_inner()` on the `Query` and expecting the full `'w` lifetime, we introduce a new `QueryLens::query_inner()` method. This is only valid for `ReadOnlyQueryData`, so it may safely hand out a copy of the permission for the full `'w` lifetime. Since `get_inner()` and `iter_inner()` were only valid on `ReadOnlyQueryData` prior to #15858, that should cover any uses that relied on the longer lifetime. ## Migration Guide Users of `QueryLens::query()` who were calling `get_inner()` or `iter_inner()` will need to replace the call with `QueryLens::query_inner()`. |
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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).
For information on writing tests see compile_fail_utils/README.md.