Box-on-write

Previously, this crate offered a boxed version of Cow that would box values instead of converting them to a different type like Vec or String. Due to the previous implementation, a lack of desire for use, and breakage due to Rust issue #46205, this crate is no longer maintained. The latest version of this crate, 2.0.1, exports no code and clarifies that it should not be used.

lib.rs:

This crate is deprecated and will no longer compile on current versions of Rust.