// build.rs
use std::env;
use std::fs;
use std::path::Path;
fn main() {
let out_dir = env::var_os("OUT_DIR").unwrap();
let dest_path = Path::new(&out_dir).join("hello.rs");
fs::write(
&dest_path,
"pub fn message() -> &'static str {
\"Hello, World!\"
}
",
)
.unwrap();
println!("cargo:rerun-if-changed=build.rs");
}