Cargo Features

[dependencies]
proc-macro2-diagnostics = { version = "0.10.1", default-features = false, features = ["colors"] }
default = colors

The colors feature is set by default whenever proc-macro2-diagnostics is added without default-features = false somewhere in the dependency tree.

colors default = yansi

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.

yansi colors