Use never_say_never hack to work around Rust 2024 regression for fn traits #18804
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…raits (#18804) # Objective After #17967, closures which always panic no longer satisfy various Bevy traits. Principally, this affects observers, systems and commands. While this may seem pointless (systems which always panic are kind of useless), it is distinctly annoying when using the `todo!` macro, or when writing tests that should panic. Fixes #18778. ## Solution - Add failing tests to demonstrate the problem - Add the trick from [`never_say_never`](https://docs.rs/never-say-never/latest/never_say_never/) to name the `!` type on stable Rust - Write looots of docs explaining what the heck is going on and why we've done this terrible thing ## To do Unfortunately I couldn't figure out how to avoid conflicting impls, and I am out of time for today, the week and uh the week after that. Vacation! If you feel like finishing this for me, please submit PRs to my branch and I can review and press the button for it while I'm off. Unless you're Cart, in which case you have write permissions to my branch! - [ ] fix for commands - [ ] fix for systems - [ ] fix for observers - [ ] revert bevyengine/bevy-website#2092 ## Testing I've added a compile test for these failure cases and a few adjacent non-failing cases (with explicit return types). --------- Co-authored-by: Carter Anderson <mcanders1@gmail.com>
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Objective
After #17967, closures which always panic no longer satisfy various Bevy traits. Principally, this affects observers, systems and commands.
While this may seem pointless (systems which always panic are kind of useless), it is distinctly annoying when using the
todo!macro, or when writing tests that should panic.Fixes #18778.
Solution
never_say_neverto name the!type on stable RustTo do
Unfortunately I couldn't figure out how to avoid conflicting impls, and I am out of time for today, the week and uh the week after that. Vacation! If you feel like finishing this for me, please submit PRs to my branch and I can review and press the button for it while I'm off.
Unless you're Cart, in which case you have write permissions to my branch!
Testing
I've added a compile test for these failure cases and a few adjacent non-failing cases (with explicit return types).