Firefox contribution notes #

In the process of making several Firefox PRs, I've needed to keep notes on what or how to do various things -- mostly because I'm not working frequently enough in the repo to have this become muscle memory. The notes are pretty raw, but its mostly meant to be a quick scan resource.

• Quick Ref
• WPT guidelines for FF
• ./mach ide vscode is a nice setup
• Updating to latest:
  • the obj dir name includes the macOS version (e.g. obj-aarch64-apple-darwin27.2.0), so an OS update starts a fresh one. Delete the old obj dirs
• ./mach build
  • ./mach run launches the build
  • build troubleshooting:
    • Failed to find an adequate linker: mach couldn't install its Python packages, so it skipped toolchain bootstrap and fell back to the system clang. If you use a custom pip/uv index, point uv at PyPI and recreate mach's virtualenvs:
      • rm -rf ~/.mozbuild/srcdirs/firefox-*/_virtualenvs
      • UV_NO_CONFIG=1 UV_DEFAULT_INDEX=https://pypi.org/simple ./mach build
    • Rust compiler 1.92.0 is too old: rustup update stable
• ./mach test
• git stuff
  • use the right commit message
  • git commit —amend for updates
  • moz-phab to push