Cargo Features

Swagger-ui has no features set by default.

[dependencies]
swagger-ui = { version = "0.1.5", features = ["rocket"] }
rocket = rocket-swagger-ui

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.

rocket-swagger-ui rocket?