bevy/crates/bevy_ecs/macros
JoJoJet db8d3651e0
Migrate the rest of the engine to UnsafeWorldCell (#8833)
# Objective

Follow-up to #6404 and #8292.

Mutating the world through a shared reference is surprising, and it
makes the meaning of `&World` unclear: sometimes it gives read-only
access to the entire world, and sometimes it gives interior mutable
access to only part of it.

This is an up-to-date version of #6972.

## Solution

Use `UnsafeWorldCell` for all interior mutability. Now, `&World`
*always* gives you read-only access to the entire world.

---

## Changelog

TODO - do we still care about changelogs?

## Migration Guide

Mutating any world data using `&World` is now considered unsound -- the
type `UnsafeWorldCell` must be used to achieve interior mutability. The
following methods now accept `UnsafeWorldCell` instead of `&World`:

- `QueryState`: `get_unchecked`, `iter_unchecked`,
`iter_combinations_unchecked`, `for_each_unchecked`,
`get_single_unchecked`, `get_single_unchecked_manual`.
- `SystemState`: `get_unchecked_manual`

```rust
let mut world = World::new();
let mut query = world.query::<&mut T>();

// Before:
let t1 = query.get_unchecked(&world, entity_1);
let t2 = query.get_unchecked(&world, entity_2);

// After:
let world_cell = world.as_unsafe_world_cell();
let t1 = query.get_unchecked(world_cell, entity_1);
let t2 = query.get_unchecked(world_cell, entity_2);
```

The methods `QueryState::validate_world` and
`SystemState::matches_world` now take a `WorldId` instead of `&World`:

```rust
// Before:
query_state.validate_world(&world);

// After:
query_state.validate_world(world.id());
```

The methods `QueryState::update_archetypes` and
`SystemState::update_archetypes` now take `UnsafeWorldCell` instead of
`&World`:

```rust
// Before:
query_state.update_archetypes(&world);

// After:
query_state.update_archetypes(world.as_unsafe_world_cell_readonly());
```
2023-06-15 01:31:56 +00:00
..
src Migrate the rest of the engine to UnsafeWorldCell (#8833) 2023-06-15 01:31:56 +00:00
Cargo.toml update syn, encase, glam and hexasphere (#8573) 2023-05-16 01:24:17 +00:00