Read-only cown v2

src/rt/debug/systematic.h

@@ -270,9 +270,10 @@ namespace verona::rt
     /**
      * Switches thread in systematic testing.
      */
-    static void yield()
+    static bool yield()
     {
       yield_until(true_thunk);
+      return true;
     }
 
     /**
@@ -355,8 +356,9 @@ namespace verona::rt
     }
   };
 
-  static void yield()
+  static bool yield()
   {
     Systematic::yield();
+    return true;
   }
 } // namespace verona::rt

src/rt/object/object.h

@@ -12,7 +12,7 @@
 namespace verona::rt
 {
   class Cown;
-  static void yield();
+  static bool yield();
   /**!object.md
    * Object representation
    * =====================

src/rt/sched/behaviour.h

@@ -101,6 +101,8 @@ namespace verona::rt
         auto* s = new (&slots[i]) Slot(requests[i].cown());
         if (requests[i].is_move())
           s->set_move();
+        if (requests[i].is_read())
+          s->set_read_only();
       }
 
       return body;