type Mutt = Dog & Cat

const imposter: Mutt = { bark: () => console.log("woof"), meow: () => console.log("meow"), }

You're both misunderstanding parent's point as well as the original point. Nobody ever claimed your link wouldn't compile.

I see what you mean, thanks

Well imo GP is fundamentally misunderstanding TypeScript. It's explicitly a structural language not a nominal one. It goes against the entire design philosophy of TS