This is a working document intended to outline some commands contributors can use to debug various parts of Foundry.
All crates use tracing for logging. A console formatter is installed in each binary (cast, forge, anvil).
By setting RUST_LOG=<filter> you can get a lot more info out of Forge and Cast. For example, running Forge with RUST_LOG=forge will emit all logs of the cli crate, same for Cast.
The most basic valid filter is a log level, of which these are valid:
errorwarninfodebugtrace
Filters are explained in detail in the env_logger crate docs.
You can also use the dbg! macro from Rust's standard library.