MinGW: Fix errors due to Native TLS with

libs/temporal/tempo.cc

@@ -52,6 +52,14 @@ SerializedRCUManager<TempoMap> TempoMap::_map_mgr (0);
 thread_local TempoMap::SharedPtr TempoMap::_tempo_map_p;
 PBD::Signal<void()> TempoMap::MapChanged;
 
+#ifdef MINGW_NATIVE_TLS
+TempoMap::SharedPtr&
+TempoMap::_tempo_map_ref ()
+{
+	return _tempo_map_p;
+}
+#endif
+
 #ifndef NDEBUG
 #define TEMPO_MAP_ASSERT(expr) TempoMap::map_assert(expr, #expr, __FILE__, __LINE__)
 #else

libs/temporal/temporal/tempo.h

@@ -753,6 +753,12 @@ class /*LIBTEMPORAL_API*/ TempoMap : public PBD::StatefulDestructible
 	typedef std::shared_ptr<TempoMap> WritableSharedPtr;
   private:
 	static thread_local SharedPtr _tempo_map_p;
+#ifdef MINGW_NATIVE_TLS
+  /* Due to Native TLS recently being added, errors come from
+     thread_local variables during external linkage.
+     See https://github.com/msys2/MINGW-packages/issues/29272 */
+	static LIBTEMPORAL_API SharedPtr& _tempo_map_ref ();
+#endif
 	static SerializedRCUManager<TempoMap> _map_mgr;
 	static bool fetch_condition ();
   public:
@@ -762,9 +768,15 @@ class /*LIBTEMPORAL_API*/ TempoMap : public PBD::StatefulDestructible
   public:
 	LIBTEMPORAL_API static void init ();
 
+#ifndef MINGW_NATIVE_TLS
 	LIBTEMPORAL_API static void      update_thread_tempo_map() { _tempo_map_p = _map_mgr.reader(); }
 	LIBTEMPORAL_API static SharedPtr use() { assert (_tempo_map_p); return _tempo_map_p; }
 	LIBTEMPORAL_API static SharedPtr fetch() { assert (fetch_condition()); update_thread_tempo_map(); return _tempo_map_p; }
+#else
+	LIBTEMPORAL_API static void      update_thread_tempo_map() { _tempo_map_ref() = _map_mgr.reader(); }
+	LIBTEMPORAL_API static SharedPtr use() { assert (_tempo_map_ref()); return _tempo_map_ref(); }
+	LIBTEMPORAL_API static SharedPtr fetch() { assert (fetch_condition()); update_thread_tempo_map(); return _tempo_map_ref(); }
+#endif
 	/* No fetch condition for this, to be used only in association with LocalTempoMapScope */
 	LIBTEMPORAL_API static SharedPtr global_fetch() { return _map_mgr.reader(); }
 
@@ -778,7 +790,11 @@ class /*LIBTEMPORAL_API*/ TempoMap : public PBD::StatefulDestructible
 	 * can be used on either a write_copy()'ed map, or one obtained via the
 	 * RCU reader() method.
 	 */
+#ifndef MINGW_NATIVE_TLS
 	LIBTEMPORAL_API static void      set (SharedPtr new_map) { _tempo_map_p = new_map; }
+#else
+	LIBTEMPORAL_API static void      set (SharedPtr new_map) { _tempo_map_ref() = new_map; }
+#endif
 
 	/* API for typical tempo map changes */
 

wscript

@@ -1272,6 +1272,15 @@ int main () { return 0; }
         #    conf.env.append_value('CFLAGS', '-DUSE_PTW32_SEMAPHORE')
         #    conf.env.append_value('CXXFLAGS', '-DUSE_PTW32_SEMAPHORE')
 
+        # Check if GCC was built with native TLS support
+        # gcc -v prints configure flags to stderr, not stdout
+        gcc_config = subprocess.run([str(conf.env['CC'][0]), '-v'], capture_output=True, text=True).stderr
+        have_native_tls = '--enable-tls' in gcc_config
+
+        if have_native_tls:
+            conf.env.append_value('CFLAGS', '-DMINGW_NATIVE_TLS')
+            conf.env.append_value('CXXFLAGS', '-DMINGW_NATIVE_TLS')
+
     if Options.options.dist_target == 'msvc':
         conf.env.append_value('CFLAGS', '-DPLATFORM_WINDOWS')
         conf.env.append_value('CFLAGS', '-DCOMPILER_MSVC')