Standalone bevy_ecs tests fail to compile

[alice-i-cecile]

Bevy version

ed13d9b

What you did

Attempted to run a single test in bevy_ecs.

The exact command run was:

cargo test --package bevy_ecs --lib --all-features -- world::error::tests::fixing_panicking_entity_commands --exact --show-output

That particular test doesn't exist on main: I was attempting to fix a different issue.

What went wrong

error[E0599]: no method named `catch_unwind` found for struct `AssertUnwindSafe<impl Future<Output = _>>` in the current scope
   --> crates/bevy_tasks/src/task_pool.rs:484:22
    |
483 |                   let _result = AssertUnwindSafe(executor.run(tick_forever))
    |  _______________________________-
484 | |                     .catch_unwind()
    | |                     -^^^^^^^^^^^^ method not found in `AssertUnwindSafe<impl Future<Output = _>>`
    | |_____________________|
    |

error[E0599]: no method named `catch_unwind` found for struct `AssertUnwindSafe<{async block@crates/bevy_tasks/src/task_pool.rs:500:36: 500:41}>` in the current scope
   --> crates/bevy_tasks/src/task_pool.rs:505:62
    |
505 |                 let _result = AssertUnwindSafe(tick_forever).catch_unwind().await.is_ok();
    |                                                              ^^^^^^^^^^^^ method not found in `AssertUnwindSafe<{async block@crates/bevy_tasks/src/task_pool.rs:500:36: 500:41}>`

error[E0599]: no method named `catch_unwind` found for struct `AssertUnwindSafe<impl Future<Output = _>>` in the current scope
   --> crates/bevy_tasks/src/task_pool.rs:525:22
    |
524 |                   let _result = AssertUnwindSafe(executor.run(tick_forever))
    |  _______________________________-
525 | |                     .catch_unwind()
    | |                     -^^^^^^^^^^^^ method not found in `AssertUnwindSafe<impl Future<Output = _>>`
    | |_____________________|
    |

error[E0599]: no method named `catch_unwind` found for struct `AssertUnwindSafe<{async block@crates/bevy_tasks/src/task_pool.rs:540:36: 540:41}>` in the current scope
   --> crates/bevy_tasks/src/task_pool.rs:545:62
    |
545 |                 let _result = AssertUnwindSafe(tick_forever).catch_unwind().await.is_ok();
    |                                                              ^^^^^^^^^^^^ method not found in `AssertUnwindSafe<{async block@crates/bevy_tasks/src/task_pool.rs:540:36: 540:41}>`

error[E0599]: no method named `catch_unwind` found for struct `AssertUnwindSafe<Fut>` in the current scope
   --> crates/bevy_tasks/src/task_pool.rs:649:40
    |
649 |             .spawn(AssertUnwindSafe(f).catch_unwind())
    |                                        ^^^^^^^^^^^^ method not found in `AssertUnwindSafe<Fut>`

error[E0599]: no method named `catch_unwind` found for struct `AssertUnwindSafe<Fut>` in the current scope
   --> crates/bevy_tasks/src/task_pool.rs:665:40
    |
665 |             .spawn(AssertUnwindSafe(f).catch_unwind())
    |                                        ^^^^^^^^^^^^ method not found in `AssertUnwindSafe<Fut>`

error[E0599]: no method named `catch_unwind` found for struct `AssertUnwindSafe<Fut>` in the current scope
   --> crates/bevy_tasks/src/task_pool.rs:682:40
    |
682 |             .spawn(AssertUnwindSafe(f).catch_unwind())
    |                                        ^^^^^^^^^^^^ method not found in `AssertUnwindSafe<Fut>`

error[E0432]: unresolved import `__automatic_type_registration_impl`
   --> crates/bevy_reflect/src/lib.rs:820:17
    |
820 |         pub use __automatic_type_registration_impl::*;
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ use of unresolved module or unlinked crate `__automatic_type_registration_impl`
    |
    = help: if you wanted to use a crate named `__automatic_type_registration_impl`, use `cargo add __automatic_type_registration_impl` to add it to your `Cargo.toml`

Additional information

Likely introduced by #15030.

[alice-i-cecile]

This compile failure only occurs with --all-features enabled.

[eugineerd]

__automatic_type_registration_impl error is due to reflect_auto_register enabling just bevy_reflect/auto_register, which requires either bevy_reflect/auto_register_inventory or bevy_reflect/auto_register_static to function. I think the reason this is separated into 3 features is because if we make auto_register == auto_register_inventory, then in the auto_register_static case we'd still have to download inventory since it'd require auto_register feature. I think it might be fine since inventory should still compile even on unsupported systems, it would just not do anything.

I don't know what all the catch_unwind errors are about though.

[alice-i-cecile]

Working notes:

The catch_unwind errors appear to be in bevy_tasks, and ultimately come from core. Looking at the source code, I noticed a since = "1.9.0" annotation. I bet I need to update Rust locally!

And doing so updates me to... Rust 1.89. What the heck. Okay, opening the docs, the problem becomes clearer: catch_unwind is an std method only!

Okay, so the whole of task_pool.rs requires std, which is not being enable during tests. That's good and bad: we want bevy_ecs to be able to run without std. Bad because somehow this code was getting compiled in?

Uh, that's not great. Our feature flagging should have stopped that.

Wait no, we're running these tests with all-features? What? That's extra weird.

Conclusion: paging @bushrat011899 @NthTensor for help. Something is broken with the std cfg flags in bevy_tasks, likely originating in #20369.

To reproduce, run:

cargo test --package bevy_ecs --lib --all-features -- change_detection::tests::change_expiration --exact --show-output 

Critically, this only occurs with all-features enabled.

[NthTensor]

Sounds like a mistake, I'll look into this tomorrow.