use rustc_version::{version_meta, Channel}; fn main() { // Set cfg flags depending on release channel let channel = match version_meta().unwrap().channel { Channel::Stable => "CHANNEL_STABLE", Channel::Beta => "CHANNEL_BETA", Channel::Nightly => "CHANNEL_NIGHTLY", Channel::Dev => "CHANNEL_DEV", }; println!("cargo:rustc-cfg={}", channel) }