Cargo Features

SmallVec has no features set by default.

[dependencies]
smallvec = { version = "2.0.0-alpha.1", features = ["write", "specialization", "may_dangle", "serde"] }
write
specialization
may_dangle

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features.

serde implicit feature