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 | |
); | |
} | |
} | |
} |