Cargo Features

codespan_reporting has no features set by default.

[dependencies]
codespan-reporting = { version = "0.11.1", features = ["serialization", "ascii-only"] }
serialization = serde

Enables 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.

ascii-only

Features from optional dependencies

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

serde serialization?