in Sources/SwiftDriver/IncrementalCompilation/DependencyKey.swift [395:405]
func kindOrdering(_ d: DependencyKey.Designator) -> Int {
switch d {
case .topLevel: return 1
case .dynamicLookup: return 2
case .externalDepend: return 3
case .sourceFileProvide: return 4
case .nominal: return 5
case .potentialMember: return 6
case .member: return 7
}
}