Cargo Features

tuple = { version = "0.5.2", default-features = false, features = ["std", "impl_num", "impl_simd", "impl_serde", "nightly"] }
default = impl_num, impl_serde, std

These default features are set whenever tuple is added without default-features = false somewhere in the dependency tree.

std default
impl_num default = num-traits
impl_simd = nightly
impl_serde default = serde
nightly impl_simd?

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.

num-traits impl_num
serde impl_serde