Trait sugar syntax for `maker` `trait` and implementing the same maker trait for multiple type

[Thomas-Mewily]

Hello there, here is just a personal suggestion to keep the consistency between declaring a empty struct / marker trait, nothings really important but anyway ^^

struct Empty;   // ok
struct Empty {} // ok

trait SignedInteger;   // currently not ok 
trait SignedInteger {} // ok

impl SignedInteger for i8;   // currently not ok
impl SignedInteger for i8 {} // ok

Also, sometime implementing the same maker trait for multiples types can be helpful (instead of using macro) :

impl SignedInteger for i8, i16, i32, i64, isize;   // currently not ok
impl SignedInteger for i8, i16, i32, i64, isize {} // currently not ok

[kennytm]

consistency between declaring a empty struct / marker trait

struct Empty; and struct Empty {} are not equivalent. The former also allows you to create an instance like let x = Empty; which is not possible for the latter.

So there is no "consistency", and it is not an applicable rationale here.