Firefox panic with parking_lot (Parking not supported on this platform)

[Titaniumtown]

Describe the bug
With the latest egui commit, egui randomly fails with the error "Parking not supported on this platform" in relation to parking_lot.

To Reproduce
Steps to reproduce the behavior:

1. Browse to egui site using latest commit of egui with Firefox browser
2. Interact with site for a bit
3. Observe panic in browser console

Expected behavior
The site should run fine on Firefox

Screenshots

Desktop (please complete the following information):

• OS: Arch Linux
• Browser: Firefox
• Version: 100 (nightly)

[emilk]

As "DusterTheFirst" remarked on the egui Discord, this seems to be related to parking_lot relying on atomics which are not enabled on webkitgtk by default:

https://github.com/Amanieu/parking_lot/blob/1cf12744d097233316afa6c8b7d37389e4211756/core/src/thread_parker/wasm.rs#L8-L9
https://github.com/Amanieu/parking_lot/blob/1cf12744d097233316afa6c8b7d37389e4211756/core/src/thread_parker/mod.rs#L69-L79

I don't know why ThreadParker is being used though.

I don't understand how ThreadParker is even a thing in wasm32 - there are no threads in wasm (yet).

I don't know if this should be opened as an issue in parking_lot and/or if we should change epaint::mutex to always use atomic_refcell instead of parking_lot when compiling for wasm32.

[Titaniumtown]

relying on atomics which are not enabled on webkitgtk by default:

This is on firefox though.

[emilk]

It's a bit dissapointing (and surprising) that you don't get a proper Rust callstack in the console - or did you accidentally crop that from the image?

[emilk]

Ok, then I'll just revert to using atomic_refcell on wasm targets and it should be all good again. Until we use a 3rd party library that uses parking_lot…

[emilk]

Please try out #1404 @Titaniumtown

[imxood]

Using latest code, and this is Ok,
OS: Deepin Linux
Browser: Firefox