Cargo Features

revel-taglib has no features set by default.

[dependencies]
revel-taglib = { version = "2.0.1", features = ["use-pkgconfig"] }
use-pkgconfig = pkg-config

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.

pkg-config build use-pkgconfig?