1use std::process::Command;
2
3fn main() {
4 if let Ok(v) = Command::new("rustc").arg("--version").output() {
5 let s = match String::from_utf8(v.stdout) {
6 Ok(s) => s,
7 _ => return,
8 };
9 if !s.starts_with("rustc ") {
10 return;
11 }
12 if let Some(s) = s.split(' ').skip(1).next() {
13 let s = s.split('.').collect::<Vec<_>>();
14 if s.len() < 3 {
15 return;
16 }
17 if s[0] == "1" && u32::from_str_radix(&s[1], 10)
18 .map(|nb| nb < 30)
19 .unwrap_or_else(|_| false) {
20 println!("cargo:rustc-cfg=feature=\"old_macros\"");
21 }
22 }
23 }
24}