Gn Check Autofix

GN Check Autofix

This skill provides instructions for using tools_webrtc/gn_check_autofix.py to automatically resolve common GN build configuration errors in WebRTC.

Core Workflows

Fix Missing Dependencies

When you see "Include not allowed" errors from gn gen --check, use this workflow:

1. Run the autofix tool on your output directory:

   tools_webrtc/gn_check_autofix.py -C <dir>
   

2. The tool will:
   • Identify targets missing dependencies.
   • Add the missing deps to the appropriate BUILD.gn files.
   • Automatically run gn format on modified files.

Fix rtc_source_set Violations

If you see "rtc_source_set shall not contain cc files", the tool will automatically convert them to rtc_library:

1. Run the tool:

   tools_webrtc/gn_check_autofix.py -C <dir>
   

Clean Up Dependencies

To remove all non-absolute dependencies (those not starting with //) from specific BUILD.gn files:

tools_webrtc/gn_check_autofix.py -r path/to/BUILD.gn

Note: This preserves absolute dependencies (starting with //) and targets ending in _test, _tests, _unittest, or _unittests.

Integration with Include Cleaner

This tool is the recommended second step after running webrtc-include-cleaner. While the include cleaner updates your C++ source files, gn-check-autofix synchronizes your BUILD.gn files to match.

Parameters

• -C <dir>: Path to a local build directory (e.g., out/Default). The tool internally runs gn gen --check --error-limit=20000.
• -r <files>: Remove all non-absolute dependencies from the specified files.
• --error-limit: Can be used to override the default error cap.

Post-Fix Steps

After the tool runs, always verify the changes:

1. Deduplicate: The tool may occasionally add a dependency that is already present. Check the deps list for duplicates.
2. Regenerate GN: Run gn gen <dir> to confirm errors are resolved.
3. Format: The tool runs gn format, but a final git cl format is recommended for consistency.
4. Review: Check the diff to ensure dependencies were added to the correct targets.

Source: signalapp/webrtc — distributed by TomeVault.