Cargo Features

boolean = { version = "0.3.0", default-features = false, features = ["global_values", "has_alloc"] }
default = global_values, has_alloc

These default features are set whenever boolean is added without default-features = false somewhere in the dependency tree.

global_values default

let this crate define True as Boolean::True and False as Boolean::False

has_alloc default

behaviour may differ when alloc is available e.g., behaviour of FromStr allows any casing (upper/lowercase) when this feature is enabled (the alloc crate should be available!)