Cargo Features

[dependencies]
rustler_sys = { version = "2.4.0", default-features = false, features = ["nif_version_2_14", "nif_version_2_15", "nif_version_2_16", "nif_version_2_17"] }
default = nif_version_2_15

The nif_version_2_15 feature is set by default whenever rustler_sys is added without default-features = false somewhere in the dependency tree.

nif_version_2_14 nif_version_2_15
nif_version_2_15 default nif_version_2_16? = nif_version_2_14

Affects rustler_sys_api::ErlNifTermType

nif_version_2_16 nif_version_2_17? = nif_version_2_15
nif_version_2_17 = nif_version_2_16

Affects rustler_sys_api::ErlNifOption