bevy/docs/debugging.md

Debugging

Macro Debugging

• Print the final output of a macro using cargo rustc --profile=check -- -Zunstable-options --pretty=expanded
  • Alternatively you could install and use cargo expand which adds syntax highlighting to the terminal output.
    • Additionally get pager by piping to less ( on Unix systems ): cargo expand --color always | less -R
• Print output during macro compilation using eprintln!("hi");

WGPU Tracing

When a suspected wgpu error occurs, you should capture a wgpu trace so that Bevy and wgpu devs can debug using the wgpu player tool.

To capture a wgpu trace:

1. Create a new wgpu_trace folder in the root of your cargo workspace
2. Add the "wgpu_trace" feature to the bevy crate. (ex: cargo run --example features wgpu_trace)
3. Zip up the wgpu_trace folder and attach it to the relevant issue. New wgpu issues should generally be created here. Please include the wgpu revision in your bug reports. You can find the revision in the Cargo.lock file in your workspace.