Cargo Features

reducer = { version = "3.0.1", default-features = false, features = ["std", "alloc", "async"] }
default = async

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

std async = alloc
alloc std?
async default = futures, pin-project, std

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features.

futures async
pin-project async