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