The Rust standard library has contortions in order to support invalid UTF-16. To do this it uses an encoding called "WTF-8"[0], which is an extension to UTF-8.

The Rust standard library has contortions in order to support invalid UTF-16. To do this it uses an encoding called "WTF-8"[0], which is an extension to UTF-8. If the standard library dropped this requirement and only supported valid Unicode then it could simply use normal UTF-8 instead of WTF-8. [0]: https://simonsapin.github.io/wtf-8/ https://simonsapin.github.io/wtf-8/