Cargo Features

[dependencies]
range-reader = { version = "0.2.0", default-features = false, features = ["sync", "async"] }
default = async, sync

These default features are set whenever range-reader is added without default-features = false somewhere in the dependency tree.

sync default
async default = futures

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.

futures async