Cargo Features

xproto = { version = "2.0.1", default-features = false, features = ["protocol-support"] }
default = protocol-support

The protocol-support feature is set by default whenever xproto is added without default-features = false somewhere in the dependency tree.

protocol-support default = protocol, protocol-derive

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.

protocol protocol-support
protocol-derive protocol-support