1 //! ## Documentation: Feature Flags 2 //! 3 //! Available [compile-time feature flags](https://doc.rust-lang.org/cargo/reference/features.html#dependency-features) 4 //! 5 //! #### Default Features 6 //! 7 //! * **std**: _Not Currently Used._ Placeholder for supporting `no_std` environments in a backwards compatible manner. 8 //! * **color**: Turns on colored error messages. 9 //! * **suggestions**: Turns on the `Did you mean '--myoption'?` feature for when users make typos. 10 //! 11 //! #### Optional features 12 //! 13 //! * **deprecated**: Guided experience to prepare for next breaking release (at different stages of development, this may become default) 14 //! * **derive**: Enables the custom derive (i.e. `#[derive(Parser)]`). Without this you must use one of the other methods of creating a `clap` CLI listed above. 15 //! * **cargo**: Turns on macros that read values from [`CARGO_*` environment variables](https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-crates). 16 //! * **env**: Turns on the usage of environment variables during parsing. 17 //! * **regex**: Enables regex validators. 18 //! * **unicode**: Turns on support for unicode characters (including emoji) in arguments and help messages. 19 //! * **wrap_help**: Turns on the help text wrapping feature, based on the terminal size. 20 //! 21 //! #### Experimental features 22 //! 23 //! **Warning:** These may contain breaking changes between minor releases. 24 //! 25 //! * **unstable-replace**: Enable [`Command::replace`](https://github.com/clap-rs/clap/issues/2836) 26 //! * **unstable-grouped**: Enable [`ArgMatches::grouped_values_of`](https://github.com/clap-rs/clap/issues/2924) 27 //! * **unstable-v4**: Preview features which will be stable on the v4.0 release 28