How marker traits works

[jofas]

Great answer here on URLO I think you might find useful:

Understanding the marker traits

There's a few different ideas going on here. In one sense, a marker trait is just a trait that doesn't have any items. Even without any special compiler support, this can sometimes be useful (e.g. sealed traits.) In another sense, there is an unstable #[marker] attribute that you can put on marker traits (in the above sense) in order to opt into the overlapping implementations of RFC 1268 (also unstable). And yet another sense are "the things in std::marker". Most of those things are marker…