use autocfg::AutoCfg;
fn main() {
match AutoCfg::new() {
Ok(ac) => {
// The #[track_caller] attribute was stabilized in rustc 1.46.0.
if ac.probe_rustc_version(1, 46) {
autocfg::emit("tokio_track_caller")
}
}
Err(e) => {
// If we couldn't detect the compiler version and features, just
// print a warning. This isn't a fatal error: we can still build
// Tokio, we just can't enable cfgs automatically.
println!(
"cargo:warning=tokio: failed to detect compiler features: {}",
e
);
}
}
}