Cargo Features

lockable = { version = "0.0.8", default-features = false, features = ["lru"] }
default = lru

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

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.

lru default