extern crate rustc_version; use rustc_version::{version_meta, Channel}; fn main() { // Copied and adapted from // https://github.com/Kimundi/rustc-version-rs/blob/1d692a965f4e48a8cb72e82cda953107c0d22f47/README.md#example // Licensed under Apache-2.0 + MIT match version_meta().unwrap().channel { Channel::Stable => { println!("cargo:rustc-cfg=RUSTC_WITHOUT_SPECIALIZATION"); } Channel::Beta => { println!("cargo:rustc-cfg=RUSTC_WITHOUT_SPECIALIZATION"); } Channel::Nightly => { println!("cargo:rustc-cfg=RUSTC_WITH_SPECIALIZATION"); } Channel::Dev => { println!("cargo:rustc-cfg=RUSTC_WITH_SPECIALIZATION"); } } }