From bf57209f9e1c9f9f639c2d63c7674c3757750eb5 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 16 Dec 2016 16:08:06 +0200
Subject: Work around unexportable thread-local variables on Win32

---
 butl/diagnostics.cxx |  2 +-
 butl/utility         | 18 ++++++++++++++----
 butl/utility.cxx     |  7 ++++++-
 3 files changed, 21 insertions(+), 6 deletions(-)

(limited to 'butl')

diff --git a/butl/diagnostics.cxx b/butl/diagnostics.cxx
index ad84810..9d74747 100644
--- a/butl/diagnostics.cxx
+++ b/butl/diagnostics.cxx
@@ -39,7 +39,7 @@ namespace butl
     // mechanism in destructors, which is not a big deal, except for one
     // place: exception_guard. Thus the ugly special check.
     //
-    if (!std::uncaught_exception () || exception_unwinding_dtor)
+    if (!std::uncaught_exception () || exception_unwinding_dtor ())
       flush ();
 #endif
   }
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;
       }
     }
 
diff --git a/butl/utility.cxx b/butl/utility.cxx
index 032d178..f64e7c8 100644
--- a/butl/utility.cxx
+++ b/butl/utility.cxx
@@ -12,6 +12,11 @@ namespace butl
 #else
   __thread
 #endif
-  bool exception_unwinding_dtor = false;
+  bool exception_unwinding_dtor_ = false;
+#endif
+
+#ifdef _WIN32
+  bool&
+  exception_unwinding_dtor () {return exception_unwinding_dtor_;}
 #endif
 }
-- 
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