Added guards so dlib::async code isn't pulled in when using old versions of…

Added guards so dlib::async code isn't pulled in when using old versions of visual studio (since they don't support c++11).

dlib/all/source.cpp

@@ -26,7 +26,6 @@
 #if __cplusplus >= 201103
 #include "../dnn/cpu_dlib.cpp"
 #include "../dnn/tensor_tools.cpp"
-#include "../threads/async.cpp"
 #endif 
 
 #ifndef DLIB_ISO_CPP_ONLY
@@ -59,6 +58,7 @@
 #include "../threads/threads_kernel_2.cpp"
 #include "../threads/threads_kernel_shared.cpp"
 #include "../threads/thread_pool_extension.cpp"
+#include "../threads/async.cpp"
 #include "../timer/timer.cpp"
 #include "../stack_trace.cpp"
 

dlib/threads.h

@@ -22,12 +22,7 @@
 #include "threads/thread_pool_extension.h"
 #include "threads/read_write_mutex_extension.h"
 #include "threads/parallel_for_extension.h"
-
-
-// things that require C++11
-#if __cplusplus >= 201103
 #include "threads/async.h"
-#endif
 
 #endif // DLIB_THREADs_
 

dlib/threads/async.cpp

@@ -3,6 +3,9 @@
 #ifndef DLIB_AsYNC_CPP_
 #define DLIB_AsYNC_CPP_ 
 
+// C++11 things don't work in old versions of visual studio 
+#if !defined( _MSC_VER) ||  _MSC_VER >= 1900
+
 #include "async.h"
 #include <stdlib.h>
 #include "../string.h"
@@ -37,6 +40,8 @@ namespace dlib
 
 // ----------------------------------------------------------------------------------------
 
+#endif
+
 #endif // DLIB_AsYNC_CPP_
 
 

dlib/threads/async.h

@@ -3,6 +3,9 @@
 #ifndef DLIB_AsYNC_Hh_
 #define DLIB_AsYNC_Hh_ 
 
+// C++11 things don't work in old versions of visual studio 
+#if !defined( _MSC_VER) ||  _MSC_VER >= 1900
+
 #include "async_abstract.h"
 #include "thread_pool_extension.h"
 #include <future>
@@ -95,6 +98,7 @@ namespace dlib
 #include "async.cpp"
 #endif
 
+#endif
 #endif // DLIB_AsYNC_Hh_