[Merged by Bors] - yeet World::components_mut >:(
#4092
Conversation
alice-i-cecile
added
C-Bug
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Maybe return a |
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We require |
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Moving out is fine, its mutating the |
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If you move something out of a mutable reference, you have to move something else in which is a non appending mutation. |
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Looking at what methods are on
additionally all fields are private, so I think there is not any harm in just removing |
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Oh nevermind |
If this is the case, would it be worth privating those APIs too, since there will be no way to reasonably use those from the World API with this removed? |
BoxyUwU
added
the
S-Ready-For-Final-Review
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bors r+ |
# Objective
make bevy ecs a lil bit less unsound
## Solution
yeet unsound API `World::components_mut`:
```rust
use bevy_ecs::prelude::*;
#[derive(Component)]
struct Foo(u8);
#[derive(Debug, Component)]
struct Bar([u8; 100]);
fn main() {
let mut world = World::new();
let e = world.spawn().insert(Foo(0)).id();
*world.components_mut() = Default::default();
let bar = world.entity_mut(e).remove::<Bar>().unwrap();
// oopsies reading memory copied from outside allocation
dbg!(bar);
}
```
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This seems like a reasonable fix for this specific instance of the problem, but I am a little concerned about what this "issue" means for Rust api design. Pasting in some of my thoughts from Discord:
@BoxyUwU then brought up this solution:
Boxy's solution is definitely a "real" solution, but its definitely not "ideal" from an implementation or documentation perspective because it adds real implementation complexity / makes it so you can't talk about Components as a simple "read / write collection" anymore. |
bors
bot
changed the title
World::components_mut >:(World::components_mut >:(
# Objective
make bevy ecs a lil bit less unsound
## Solution
yeet unsound API `World::components_mut`:
```rust
use bevy_ecs::prelude::*;
#[derive(Component)]
struct Foo(u8);
#[derive(Debug, Component)]
struct Bar([u8; 100]);
fn main() {
let mut world = World::new();
let e = world.spawn().insert(Foo(0)).id();
*world.components_mut() = Default::default();
let bar = world.entity_mut(e).remove::<Bar>().unwrap();
// oopsies reading memory copied from outside allocation
dbg!(bar);
}
```
# Objective
make bevy ecs a lil bit less unsound
## Solution
yeet unsound API `World::components_mut`:
```rust
use bevy_ecs::prelude::*;
#[derive(Component)]
struct Foo(u8);
#[derive(Debug, Component)]
struct Bar([u8; 100]);
fn main() {
let mut world = World::new();
let e = world.spawn().insert(Foo(0)).id();
*world.components_mut() = Default::default();
let bar = world.entity_mut(e).remove::<Bar>().unwrap();
// oopsies reading memory copied from outside allocation
dbg!(bar);
}
```
Objective
make bevy ecs a lil bit less unsound
Solution
yeet unsound API
World::components_mut: