Cargo Features
RuAnnoy has no features set by default.
[dependencies]
ru_annoy = { version = "0.1.3", features = ["cffi"] }- cffi = libc
Features from optional dependencies
In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality [may be removed in the future](https://rust-lang.github.io/rfcs/3491-remove-implicit-features.html).