// Detect the rustc channel // use rustc_version::{ version_meta, Channel }; fn main() { // Set cfg flags depending on release channel // match version_meta().unwrap().channel { Channel::Stable => println!( "cargo:rustc-cfg=stable" ), Channel::Beta => println!( "cargo:rustc-cfg=beta" ), Channel::Nightly => println!( "cargo:rustc-cfg=nightly" ), Channel::Dev => println!( "cargo:rustc-cfg=rustc_dev" ), } }