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use std::process::Command;
fn main() {
if let Ok(v) = Command::new("rustc").arg("--version").output() {
let s = match String::from_utf8(v.stdout) {
Ok(s) => s,
_ => return,
};
if !s.starts_with("rustc ") {
return;
}
if let Some(s) = s.split(' ').skip(1).next() {
let s = s.split('.').collect::<Vec<_>>();
if s.len() < 3 {
return;
}
if s[0] == "1" && u32::from_str_radix(&s[1], 10)
.map(|nb| nb < 30)
.unwrap_or_else(|_| false) {
println!("cargo:rustc-cfg=feature=\"old_macros\"");
}
}
}
}
|
