Panic in drop leads to a double drop on spawning a new entity

[sapir]

From #2597 (comment)

I think this happens due to Table::allocate increasing the column length before the data is actually written.

I also have a test for this, based on #2848

#[test]
fn panic_in_despawn_followed_by_insert() {
    let helper = DropTestHelper::new();

    let res = panic::catch_unwind(|| {
        let mut world = World::new();

        let e1 = world.spawn(helper.make_component(true, 0)).id();

        let _ = panic::catch_unwind(panic::AssertUnwindSafe(|| {
            world.despawn(e1);
        }));

        world.spawn(helper.make_component(true, 1));

        println!("Done inserting! Dropping world...");
    });

    let drop_log = helper.finish(res);

    assert_eq!(
        &*drop_log,
        [
            DropLogItem::Create(0),
            DropLogItem::Drop(0),
            DropLogItem::Create(1),
            DropLogItem::Drop(1)
        ]
    );
}

[james7132]

With #2848 merged, is this still an issue?

[sapir]

I updated the test code for current bevy. The test fails, it seems that object 0 is still being dropped twice.

[james7132]

Could I get the implementation of the DropLogItem and DropTestHelper here? Trying to investigate this.

[sapir]

Could I get the implementation of the DropLogItem and DropTestHelper here? Trying to investigate this.

bevy/crates/bevy_ecs/src/world/mod.rs

Line 2441 in ba9d1ef

enum DropLogItem {

bevy/crates/bevy_ecs/src/world/mod.rs

Line 2491 in ba9d1ef

struct DropTestHelper {