use std::{env, process::Command};
fn main() {
let rustc = env::var("RUSTC").unwrap();
let output = Command::new(rustc).arg("-vV").output().unwrap();
let version_info = String::from_utf8_lossy(&output.stdout);
if let Some(major) = version_info
.lines()
.find_map(|x| x.strip_prefix("LLVM version: "))
.and_then(|x| x.split('.').next())
{
println!("cargo:rustc-cfg=llvm_{}", major);
}
}