Cargo Features

[dependencies]
circular-buffer = { version = "0.1.7", default-features = false, features = ["use_std", "alloc", "unstable"] }
default = use_std

The use_std feature is set by default whenever circular-buffer is added without default-features = false somewhere in the dependency tree.

use_std default = alloc
alloc use_std
unstable

CircularBuffer has 4 features without comments.