Cargo Features

xattr = { version = "1.3.1", default-features = false, features = ["unsupported"] }
default = unsupported

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

unsupported default

Adds a dummy implementation for unsupported platforms. This is useful when developing platform-independent code that doesn't absolutely need xattr support.

You can disable this feature if you want compilation to fail on unsupported platforms. This would make sense if you absolutely need xattr support.