Cargo Features

[dependencies]
onload = { version = "0.3.0", default-features = false, features = ["9", "8", "debug"] }
default = 9

The 9 feature is set by default whenever onload is added without default-features = false somewhere in the dependency tree.

9 default
8
debug = bindgen

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.

bindgen build debug?