Cargo Features

[dependencies]
hex2d = { version = "1.1.0", default-features = false, features = ["serde-serde"] }
default = serde-serde

The serde-serde feature is set by default whenever hex2d is added without default-features = false somewhere in the dependency tree.

serde-serde default = serde, serde_derive

Needs a different name due to: https://github.com/rust-lang/cargo/issues/1286

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.

serde serde-serde
serde_derive serde-serde