Description
In WordPress/performance#2043 we found out that the Performance Lab plugin is failing some PHPCS checks from PCP.
To fix them I had to find what the specific PHPCS rules which were used and incorporate them into our ruleset. I wanted to install the PHPCS rules via composer on Packagist, but I had to install them via WPackagist. It would be nice if this installation via WPackagist wasn't required.
Then to actually incorporate the rules, I had to extract the rules from the PCP ruleset into a new ruleset XML file and include it our ruleset. I couldn't directly reference your ruleset because it includes configuration we don't want, for example the PHP 5.2+ compatibility. It would be nice if the core rules for PCP were put into a separate base ruleset which we could reference, and then you could have your ruleset reference it as well for the PCP process.
See WordPress/performance#2048 for what I've had to do to incorporate the PCP ruleset.