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 https://github.com/gfx-rs/wgpu. Please include the wgpu revision in your bug reports. You can find the revision in the Cargo.lock file in your workspace.