Cargo Features

cfg-expr has no features set by default.

cfg-expr = { version = "0.15.8", features = ["targets"] }
targets = target-lexicon

Allows parsing and handling of arbitrary target triples, including ones that are not builtin to rustc

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.

target-lexicon targets?