I see that Box is actually a tuple struct that encapsulates Unique.
From https://doc.rust-lang.org/src/core/ptr.rs.html#2336-2344 I see that Unique is essentially NonZero<*const T>.
From https://doc.rust-lang.org/src/core/nonzero.rs.html#65 I see that Nonzero is again a tuple struct that only contains T.
In summary, a Box is merely a pointer, from the view of space.
I’m using a 64-bit machine, so the raw pointer will occupy 8B.
gives me 16 instead of 8.