Fix compilation of marl::Ticket::onCall()

include/marl/ticket.h

@@ -62,6 +62,8 @@ class Ticket {
   struct Record;
 
  public:
+  using OnCall = std::function<void()>;
+
   // Queue hands out Tickets.
   class Queue {
    public:
@@ -93,7 +95,7 @@ class Ticket {
   // onCall() registers the function f to be invoked when this ticket is
   // called. If the ticket is already called prior to calling onCall(), then
   // f() will be executed immediately.
-  // F must be a function of the signature: void F()
+  // F must be a function of the OnCall signature.
   template <typename F>
   inline void onCall(F&& f) const;
 
@@ -111,7 +113,7 @@ class Ticket {
     Record* next = nullptr;  // guarded by shared->mutex
     Record* prev = nullptr;  // guarded by shared->mutex
     inline void unlink();    // guarded by shared->mutex
-    Task onCall;             // guarded by shared->mutex
+    OnCall onCall;           // guarded by shared->mutex
     bool isCalled = false;   // guarded by shared->mutex
     std::atomic<bool> isDone = {false};
   };
@@ -155,7 +157,7 @@ void Ticket::onCall(Function&& f) const {
         a();
         b();
       }
-      Task a, b;
+      OnCall a, b;
     };
     record->onCall = std::move(Joined{std::move(record->onCall), std::move(f)});
   } else {
@@ -228,13 +230,13 @@ void Ticket::Record::callAndUnlock(std::unique_lock<std::mutex>& lock) {
     return;
   }
   isCalled = true;
-  Task task;
-  std::swap(task, onCall);
+  OnCall callback;
+  std::swap(callback, onCall);
   isCalledCondVar.notify_all();
   lock.unlock();
 
-  if (task) {
-    marl::schedule(std::move(task));
+  if (callback) {
+    marl::schedule(std::move(callback));
   }
 }