| //! ## Documentation: Feature Flags |
| //! |
| //! Available [compile-time feature flags](https://doc.rust-lang.org/cargo/reference/features.html#dependency-features) |
| //! |
| //! #### Default Features |
| //! |
| //! * `std`: _Not Currently Used._ Placeholder for supporting `no_std` environments in a backwards compatible manner. |
| //! * `color`: Turns on terminal styling of help and error messages. See |
| //! [`Command::styles`][crate::Command::styles] to customize this. |
| //! * `help`: Auto-generate help output |
| //! * `usage`: Auto-generate usage |
| //! * `error-context`: Include contextual information for errors (which arg failed, etc) |
| //! * `suggestions`: Turns on the `Did you mean '--myoption'?` feature for when users make typos. |
| //! |
| //! #### Optional features |
| //! |
| //! * `deprecated`: Guided experience to prepare for next breaking release (at different stages of development, this may become default) |
| //! * `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. |
| //! * `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). |
| //! * `env`: Turns on the usage of environment variables during parsing. |
| //! * `unicode`: Turns on support for unicode characters (including emoji) in arguments and help messages. |
| //! * ``wrap_help``: Turns on the help text wrapping feature, based on the terminal size. |
| //! * `string`: Allow runtime generated strings (e.g. with [`Str`][crate::builder::Str]). |
| //! |
| //! #### Experimental features |
| //! |
| //! **Warning:** These may contain breaking changes between minor releases. |
| //! |
| //! * `unstable-v5`: Preview features which will be stable on the v5.0 release |
