Cargo Features

entity-inmemory has no features set by default.

[dependencies]
entity-inmemory = { version = "0.3.2", features = ["serde-1"] }
serde-1 = serde

Enables serde-1 of entity and rc of serde

serde:

Opt into impls for Rc<T> and Arc<T>. Serializing and deserializing these types does not preserve identity and may result in multiple copies of the same data.
Be sure that this is what you want before enabling this feature.

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-1?