Require thread_local support, move to xcode8

.travis.yml

@@ -29,6 +29,7 @@ matrix:
       compiler: gcc
     - os: osx
       compiler: clang
+      osx_image: xcode8
 
   
 env:

include/chaiscript/chaiscript_defines.hpp

@@ -48,10 +48,6 @@ static_assert(_MSC_FULL_VER >= 190024210, "Visual C++ 2015 Update 3 or later req
 #endif
 #endif
 
-#if defined(CHAISCRIPT_MSVC) ||  (defined(__GNUC__) && __GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8) || (defined(__llvm__) && !defined(CHAISCRIPT_LIBCPP))
-/// \todo Make this support other compilers when possible
-#define CHAISCRIPT_HAS_THREAD_LOCAL
-#endif
 
 #if defined(__llvm__)
 #define CHAISCRIPT_CLANG

include/chaiscript/chaiscript_threading.hpp

@@ -57,7 +57,6 @@ namespace chaiscript
 
       using std::recursive_mutex;
 
-#ifdef CHAISCRIPT_HAS_THREAD_LOCAL
       /// Typesafe thread specific storage. If threading is enabled, this class uses a mutex protected map. If
       /// threading is not enabled, the class always returns the same data, regardless of which thread it is called from.
       template<typename T>
@@ -106,69 +105,6 @@ namespace chaiscript
             }
         };
 
-#else
-
-#pragma message ("Threading without thread_local support is not well supported.")
-
-
-      /// Typesafe thread specific storage. If threading is enabled, this class uses a mutex protected map. If
-      /// threading is not enabled, the class always returns the same data, regardless of which thread it is called from.
-      /// 
-      /// This version is used if the compiler does not support thread_local
-      template<typename T>
-        class Thread_Storage
-        {
-          public:
-
-            explicit Thread_Storage(void *)
-            {
-            }
-
-            inline const T *operator->() const
-            {
-              return get_tls().get();
-            }
-
-            inline const T &operator*() const
-            {
-              return *get_tls();
-            }
-
-            inline T *operator->()
-            {
-              return get_tls().get();
-            }
-
-            inline T &operator*()
-            {
-              return *get_tls();
-            }
-
-
-          private:
-            /// \todo this leaks thread instances. It needs to be culled from time to time
-            std::shared_ptr<T> get_tls() const
-            {
-              unique_lock<mutex> lock(m_mutex);
-
-              const auto id = std::this_thread::get_id();
-              auto itr = m_instances.find(id);
-
-              if (itr != m_instances.end()) { return itr->second; }
-
-              std::shared_ptr<T> new_instance(std::make_shared<T>());
-
-              m_instances.insert(std::make_pair(id, new_instance));
-
-              return new_instance;
-            }
-
-
-            mutable mutex m_mutex;
-            mutable std::unordered_map<std::thread::id, std::shared_ptr<T> > m_instances;
-        };
-#endif // threading enabled but no tls
-
 #else // threading disabled
       template<typename T>
       class unique_lock