Error code E0322

The Sized trait was implemented explicitly.

Erroneous code example:

#![allow(unused)]
fn main() {
struct Foo;

impl Sized for Foo {} // error!
}

The Sized trait is a special trait built-in to the compiler for types with a constant size known at compile-time. This trait is automatically implemented for types as needed by the compiler, and it is currently disallowed to explicitly implement it for a type.