Constant RELAXATIONS 

const RELAXATIONS: [Relaxation; 1];

The lints the mirror is allowed to state differently, and why.

Each entry is (table, lint, workspace value, mirror value) with both values spelled exactly as they must render. A relaxation that is absent from the mirror, or present with any other value, is as much a failure as an undeclared difference: the point is that every divergence is written down here, where a reviewer sees it.