Cargo Features

[dependencies]
sfmt = { version = "0.7.0", default-features = false, features = ["thread_rng"] }
default = thread_rng

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

thread_rng default = rand

The thread_rng feature requires the rand dependency

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.

rand thread_rng