interface FileSystem {
  read: number;
}

function fn(s: WorkerFS): void;
function fn(s: FileSystem): void;
function fn(s: FileSystem|WorkerFS) { }

// This should issue a large error, not a small one
class WorkerFS implements FileSystem {
  read: string;
}

interface Alpha { x: string; }
interface Beta { y: number; }
var x: Alpha;
var y: Beta;

// Only one of these errors should be large
x = y;
x = y;

// Only one of these errors should be large
y = x;
y = x;