Cargo Features

cpreprocess has no features set by default.

[dependencies]
cpreprocess = { version = "1.0.2", features = ["nightly"] }
nightly = proc-macro-faithful-display

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.

proc-macro-faithful-display nightly?