Cargo Features

[dependencies]
swc_ecma_preset_env = { version = "7.0.0", default-features = false, features = ["serde-impl"] }
default = serde-impl

The serde-impl feature is set by default whenever swc_ecma_preset_env is added without default-features = false somewhere in the dependency tree.

serde-impl default = serde

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.

serde serde-impl