Cargo Features

[dependencies]
rand04 = { version = "0.1.1", default-features = false, features = ["std"] }
default = std

The std feature is set by default whenever rand04 is added without default-features = false somewhere in the dependency tree.

std default

Enables std of rand ^0.4.3

rand:

Option (enabled by default): without "std" rand uses libcore; this option enables functionality expected to be available on a standard platform.

rand04 has 2 features without comments.