Cargo Features

ibuilder = { version = "0.1.8", default-features = false, features = ["derive"] }
default = derive

The derive feature is set by default whenever ibuilder is added without default-features = false somewhere in the dependency tree.

derive default = ibuilder_derive

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features.

ibuilder_derive derive