Lint and Format Code

How to lint and format code.

Thunderbird's source code is linted and formatted using automated tools, which provides several benefits that include:

  • ensuring a consistent formatting style across the code base

  • preventing formatting issues from taking up developer time in code review

  • catching problems that might otherwise go unnoticed

  • making it easier for developers to write well-formatted code

Mozlint is a library that standardizes linter configuration and provides an interface for running all linters at once. It is run via mach and is run automatically by Taskcluster.

Running Linters Locally

You can run all the various linters in the tree using the mach commlint command. Simply pass in the directory or file you wish to lint (defaults to current working directory):

../mach commlint path/to/files

It works the same as regular mach lint, however it has Thunderbird configs pre-applied. If you're not familiar with using mach lint on Firefox code, see the Firefox Linting documentation to get started.

Configuring Mozlint for Thunderbird

Suite code

The Mozlint configuration files in comm/tools/lint are written so that they can be shared with the Seamonkey project. Thunderbird developers may want to set MOZLINT_NO_SUITE=1 in their environment so mach commlint will not check comm/suite/. Taskcluster will also set MOZLINT_NO_SUITE when running lint checks.


Several mozlint-based checks run automatically on Taskcluster, and more are being added. The Firefox Linting documentation is a valuable resource if you're seeing errors on your try builds. If you are not sure how to run a check locally, the mach commands run by Taskcluster are in comm/taskcluster/ci/source-test/mozlint.yml.

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