Cargo Features

[dependencies]
pico-uf2 = { version = "1.0.2", default-features = false, features = ["serial"] }
default = serial

The serial feature is set by default whenever pico-uf2 is added without default-features = false somewhere in the dependency tree.

serial default = serialport

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.

serialport serial