Cargo Features

devp2p-secp256k1 has no features set by default.

[dependencies]
devp2p-secp256k1 = { version = "0.5.6", features = ["dev", "unstable"] }
dev = clippy
unstable

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.

clippy dev?