Page on "New Type Idiom" don't mention need of using repr(transparent)

[Mart-Bogdan]

Page that describes New Type Idiom https://doc.rust-lang.org/stable/rust-by-example/generics/new_types.html

Doesn't have any mention of #[repr(transparent)], and AFAIK it would be required for it to be zero cost abstraction and don't affect how it is passed in parameters (being passed in registers instead as a pointer to struct or whatever).

P.S. even documentation on repr transparent feature has newtype as example of intended usage

https://doc.rust-lang.org/1.26.2/unstable-book/language-features/repr-transparent.html