1 files changed, 22 insertions, 0 deletions
diff --git a/tokio/build.rs b/tokio/build.rs
new file mode 100644
index 00000000..fe5c8300
--- /dev/null
+++ b/tokio/build.rs
@@ -0,0 +1,22 @@
+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
+            );
+        }
+    }
+}