tokio-macros: hard error if flavor = "local" and not tokio_unstable

Author: Twey

tokio-macros/src/entry.rs

@@ -18,7 +18,11 @@ impl RuntimeFlavor {
         match s {
             "current_thread" => Ok(RuntimeFlavor::CurrentThread),
             "multi_thread" => Ok(RuntimeFlavor::Threaded),
-            "local" => Ok(RuntimeFlavor::Local),
+            "local" => if cfg!(tokio_unstable) {
+                Ok(RuntimeFlavor::Local)
+            } else {
+                Err("The local runtime flavor is only available when `tokio_unstable` is set.".to_string())
+            }
             "single_thread" => Err("The single threaded runtime flavor is called `current_thread`.".to_string()),
             "basic_scheduler" => Err("The `basic_scheduler` runtime flavor has been renamed to `current_thread`.".to_string()),
             "threaded_scheduler" => Err("The `threaded_scheduler` runtime flavor has been renamed to `multi_thread`.".to_string()),