use rustc_version::{Channel, version_meta}; fn main() { let version_meta = version_meta().unwrap(); // To use nightly features we declare this and then we can use // #[cfg(nightly)] // for nightly only features println!("cargo:rustc-check-cfg=cfg(nightly)"); if version_meta.channel == Channel::Nightly { println!("cargo:rustc-cfg=nightly") } }