Work around unexportable thread-local variables on Win32

1 files changed, 14 insertions, 4 deletions

diff --git a/butl/utility b/butl/utility
index 02d9331..b290153 100644
--- a/butl/utility
+++ b/butl/utility
@@ -188,14 +188,24 @@ namespace butl
   // True means we are in the body of a destructor that is being called as
   // part of the exception stack unwindining.
   //
-  LIBBUTL_EXPORT
   extern
 #ifdef BUTL_CXX11_THREAD_LOCAL
   thread_local
 #else
   __thread
 #endif
-  bool exception_unwinding_dtor;
+  bool exception_unwinding_dtor_;
+
+  // On Windows one cannot export a thread-local variable so we have to
+  // use a wrapper functions.
+  //
+#ifdef _WIN32
+  LIBBUTL_EXPORT bool&
+  exception_unwinding_dtor ();
+#else
+  inline bool&
+  exception_unwinding_dtor () {return exception_unwinding_dtor_;}
+#endif
 
   template <typename F>
   struct exception_guard
@@ -205,9 +215,9 @@ namespace butl
     {
       if (std::uncaught_exception ())
       {
-        exception_unwinding_dtor = true;
+        exception_unwinding_dtor () = true;
         f_ ();
-        exception_unwinding_dtor = false;
+        exception_unwinding_dtor () = false;
       }
     }