Debugging Crubit

crubit.rs/overview/debugging

Crubit is trying to solve a hard problem and is under rapid development. Things go wrong, and it's nice to have tools and methods to diagnose those problems.

Verbose Logging

NOTE: This feature is under development and is planned to be complete by the end of 2025. There might not be much in the logs yet. See b/449749452 for status, and the design doc crubit.rs-logging.

Crubit tool invocations only log at the error level or higher to keep spam out of build logs, but the stderr logging verbosity level is configurable.

We have a shell script checked in that automates the process of invalidating your local Bazel cache and rerunning Crubit on a specific target while emitting info logs:

common/bazel_support/run_with_verbose_logging.sh

This script accepts zero or more Bazel flags (each starting with --) followed by one Bazel target label to be built.

Example usage with cc_bindings_from_rs

$ common/bazel_support/run_with_verbose_logging.sh \
    --config=llvm-unstable \
    //third_party/rust/bytes/v1:bytes

Example usage with rs_bindings_from_cc:

$ common/bazel_support/run_with_verbose_logging.sh \
    --config=llvm-unstable \
    //file/base

Implementation details

The stderr logging level is configured through the Bazel custom build setting //common/bazel_support:verbose_log_targets, which accepts a list of strings that are each interpreted as a target label. It's probably easier to just run the script.