1 files changed, 17 insertions, 0 deletions
diff --git a/cli/state.rs b/cli/state.rs
index 96be28f2f..40662b563 100644
--- a/cli/state.rs
+++ b/cli/state.rs
@@ -230,6 +230,23 @@ impl State {
       dispatcher(isolate, &state, args, zero_copy)
     }
   }
+
+  /// Quits the process if the --unstable flag was not provided.
+  ///
+  /// This is intentionally a non-recoverable check so that people cannot probe
+  /// for unstable APIs from stable programs.
+  pub fn check_unstable(&self, api_name: &str) {
+    // TODO(ry) Maybe use IsolateHandle::terminate_execution here to provide a
+    // stack trace in JS.
+    let s = self.0.borrow();
+    if !s.global_state.flags.unstable {
+      eprintln!(
+        "Unstable API '{}'. The --unstable flag must be provided.",
+        api_name
+      );
+      std::process::exit(70);
+    }
+  }
 }
 
 impl ModuleLoader for State {