Cargo Features

[dependencies]
config-better = { version = "1.3.1", default-features = false, features = ["sync", "async", "async-tokio"] }
default = sync

The sync feature is set by default whenever config-better is added without default-features = false somewhere in the dependency tree.

sync default
async = async-std
async-tokio = tokio

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.

tokio async-tokio?
async-std async?