attempt to fix crash when wml erros message showed during the loadingscreen.

src/events.cpp

@@ -39,6 +39,17 @@
 
 #define ERR_GEN LOG_STREAM(err, lg::general)
 
+namespace
+{
+	struct invoked_function_data
+	{
+		bool finished;
+		const std::function<void(void)>& f;
+
+		void call() { f(); finished = true; }
+	};
+}
+
 namespace events
 {
 
@@ -413,6 +424,12 @@ void pump()
 	int begin_ignoring = 0;
 	std::vector< SDL_Event > events;
 	while(SDL_PollEvent(&temp_event)) {
+
+		if (temp_event.type == INVOKE_FUNCTION_EVENT) {
+			static_cast<invoked_function_data*>(temp_event.user.data1)->call();
+			continue;
+		}
+
 		++poll_count;
 		peek_for_resize();
 
@@ -736,6 +753,35 @@ void peek_for_resize()
 	}
 }
 
+void call_in_main_thread(const std::function<void(void)>& f)
+{
+	if (boost::this_thread::get_id() == main_thread) {
+		// nothing special to do if called from the main thread.
+		f();
+		return;
+	}
+
+
+	invoked_function_data fdata = { false, f };
+
+	SDL_Event sdl_event;
+	SDL_UserEvent sdl_userevent;
+
+	sdl_userevent.type = INVOKE_FUNCTION_EVENT;
+	sdl_userevent.code = 0;
+	sdl_userevent.data1 = &fdata;
+	sdl_userevent.data2 = nullptr;
+
+	sdl_event.type = INVOKE_FUNCTION_EVENT;
+	sdl_event.user = sdl_userevent;
+
+	SDL_PushEvent(&sdl_event);
+
+	while (!fdata.finished) {
+		SDL_Delay(10);
+	}
+}
+
 
 } //end events namespace
 

src/events.hpp

@@ -18,6 +18,7 @@
 #include <SDL_events.h>
 #include <vector>
 #include <list>
+#include <functional>
 
 //our user-defined double-click event type
 #define DOUBLE_CLICK_EVENT SDL_USEREVENT
@@ -27,6 +28,7 @@
 #define CLOSE_WINDOW_EVENT (SDL_USEREVENT + 4)
 #define SHOW_HELPTIP_EVENT (SDL_USEREVENT + 5)
 #define DRAW_ALL_EVENT (SDL_USEREVENT + 6)
+#define INVOKE_FUNCTION_EVENT (SDL_USEREVENT + 7)
 
 namespace events
 {
@@ -111,6 +113,8 @@ void focus_handler(const sdl_handler* ptr);
 
 bool has_focus(const sdl_handler* ptr, const SDL_Event* event);
 
+void call_in_main_thread(const std::function<void (void)>& f);
+
 //event_context objects control the handler objects that SDL events are sent
 //to. When an event_context is created, it will become the current event context.
 //event_context objects MUST be created in LIFO ordering in relation to each other,

src/game_config_manager.cpp

@@ -17,6 +17,7 @@
 #include "addon/manager_old.hpp"
 #include "ai/configuration.hpp"
 #include "cursor.hpp"
+#include "events.hpp"
 #include "game_config.hpp"
 #include "gettext.hpp"
 #include "game_classification.hpp"
@@ -451,9 +452,9 @@ void game_config_manager::load_addons_cfg()
 			   n);
 
 		const std::string& report = utils::join(error_log, "\n\n");
-
-		gui2::dialogs::wml_error::display(msg1, msg2, error_addons, report,
-								  video_);
+		events::call_in_main_thread([&]() {
+			gui2::dialogs::wml_error::display(msg1, msg2, error_addons, report, video_);
+		});
 	}
 }