The VIP Code Analysis Bot runs the PHP linter (php -l) bundled with PHP, to highlight code syntax and compilation errors. All PHP files in a pull request target branch of a repository are PHP linted by the Bot.
VIP configures the Bot to syntax check each file, as syntax errors are often fatal. The Bot acts as a safeguard against such fatal errors as they usually need to be addressed before deployment.
In some cases code might intentionally contain syntax errors, such as files that are part of unit-test packages. Customizing the Bot’s behavior is useful in those cases to prevent that code from being unnecessarily highlighted during PHP linting.