> Every struct (or at least every useful struct!) refers to data Not true, zero-sized structs are quite useful too. They can be used to fulfill traits, indicat

> Every struct (or at least every useful struct!) refers to data Not true, zero-sized structs are quite useful too. They can be used to fulfill traits, indicate certain errors (often in enums), etc. A couple quick examples from the stdlib: https://github.com/rust-lang/rust/blob/1.22.1/src/libstd/sync/mpsc/mod.rs#L579-L581 https://github.com/rust-lang/rust/blob/1.22.1/src/libstd/syn... https://github.com/rust-lang/rust/blob/1.22.1/src/libstd/collections/hash/map.rs#L31-L33 https://github.com/rust-lang/rust/blob/1.22.1/src/libstd/col... I recommend watching this excellent rustconf 2017 talk for more information; it heavily features information on how zero-sized types can be used: https://www.youtube.com/watch?v=wxPehGkoNOw https://www.youtube.com/watch?v=wxPehGkoNOw