Use C++14 feature: decltype(auto)

See progschj#57

Author: jhasse

ThreadPool.hpp

@@ -9,8 +9,7 @@ class ThreadPool {
 public:
     explicit ThreadPool(size_t);
     template<class F, class... Args>
-    auto enqueue(F&& f, Args&&... args)
-        -> std::future<std::invoke_result_t<F, Args...>>;
+    decltype(auto) enqueue(F&& f, Args&&... args);
     ~ThreadPool();
 private:
     // need to keep track of threads so we can join them
@@ -54,8 +53,7 @@ inline ThreadPool::ThreadPool(size_t threads)
 
 // add new work item to the pool
 template<class F, class... Args>
-auto ThreadPool::enqueue(F&& f, Args&&... args)
-    -> std::future<std::invoke_result_t<F, Args...>>
+decltype(auto) ThreadPool::enqueue(F&& f, Args&&... args)
 {
     using return_type = std::invoke_result_t<F, Args...>;