1 A built-in trait was implemented explicitly. All implementations of the trait
2 are provided automatically by the compiler.
4 Erroneous code example:
9 impl Sized for Foo {} // error!
12 The `Sized` trait is a special trait built-in to the compiler for types with a
13 constant size known at compile-time. This trait is automatically implemented
14 for types as needed by the compiler, and it is currently disallowed to
15 explicitly implement it for a type.