Cargo Features

bip322-simple has no features set by default.

[dependencies]
bip322-simple = { version = "0.3.1", features = ["ffi"] }
ffi = libc

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.

libc ffi?