Fix crash on exit when background rendering in wayland

Disable libdecor Wayland requirement which would use an X11 fallback.

While the crash could be investigated, using libdecor at all makes
no sense in background mode.

intern/ghost/GHOST_ISystem.h

@@ -118,9 +118,11 @@ class GHOST_ISystem {
   /**
    * Creates the one and only system.
    * \param verbose: report back-ends that were attempted no back-end could be loaded.
+   * \param background: loading the system for background rendering (no visible windows).
    * \return An indication of success.
    */
-  static GHOST_TSuccess createSystem(bool verbose);
+
+  static GHOST_TSuccess createSystem(bool verbose, bool background);
   static GHOST_TSuccess createSystemBackground();
 
   /**

intern/ghost/intern/GHOST_C-api.cpp

@@ -24,7 +24,7 @@
 
 GHOST_SystemHandle GHOST_CreateSystem(void)
 {
-  GHOST_ISystem::createSystem(true);
+  GHOST_ISystem::createSystem(true, false);
   GHOST_ISystem *system = GHOST_ISystem::getSystem();
 
   return (GHOST_SystemHandle)system;

intern/ghost/intern/GHOST_ISystem.cpp

@@ -34,7 +34,7 @@ const char *GHOST_ISystem::m_system_backend_id = nullptr;
 
 GHOST_TBacktraceFn GHOST_ISystem::m_backtrace_fn = nullptr;
 
-GHOST_TSuccess GHOST_ISystem::createSystem(bool verbose)
+GHOST_TSuccess GHOST_ISystem::createSystem(bool verbose, [[maybe_unused]] bool background)
 {
   /* When GHOST fails to start, report the back-ends that were attempted.
    * A Verbose argument could be supported in printing isn't always desired. */
@@ -61,7 +61,7 @@ GHOST_TSuccess GHOST_ISystem::createSystem(bool verbose)
     if (has_wayland_libraries) {
       backends_attempted[backends_attempted_num++] = "WAYLAND";
       try {
-        m_system = new GHOST_SystemWayland();
+        m_system = new GHOST_SystemWayland(background);
       }
       catch (const std::runtime_error &) {
         delete m_system;
@@ -99,7 +99,7 @@ GHOST_TSuccess GHOST_ISystem::createSystem(bool verbose)
     if (has_wayland_libraries) {
       backends_attempted[backends_attempted_num++] = "WAYLAND";
       try {
-        m_system = new GHOST_SystemWayland();
+        m_system = new GHOST_SystemWayland(background);
       }
       catch (const std::runtime_error &) {
         delete m_system;
@@ -160,7 +160,7 @@ GHOST_TSuccess GHOST_ISystem::createSystemBackground()
   if (!m_system) {
 #if !defined(WITH_HEADLESS)
     /* Try to create a off-screen render surface with the graphical systems. */
-    success = createSystem(false);
+    success = createSystem(false, true);
     if (success) {
       return success;
     }

intern/ghost/intern/GHOST_SystemWayland.cpp

@@ -4162,7 +4162,8 @@ static const struct wl_registry_listener registry_listener = {
  * WAYLAND specific implementation of the #GHOST_System interface.
  * \{ */
 
-GHOST_SystemWayland::GHOST_SystemWayland() : GHOST_System(), display_(new GWL_Display)
+GHOST_SystemWayland::GHOST_SystemWayland(bool background)
+    : GHOST_System(), display_(new GWL_Display)
 {
   wl_log_set_handler_client(ghost_wayland_log_handler);
 
@@ -4187,6 +4188,14 @@ GHOST_SystemWayland::GHOST_SystemWayland() : GHOST_System(), display_(new GWL_Di
   wl_registry_destroy(registry);
 
 #ifdef WITH_GHOST_WAYLAND_LIBDECOR
+  /* Ignore windowing requirements when running in background mode,
+   * as it doesn't make sense to fall back to X11 because of windowing functionality
+   * in background mode, also LIBDECOR is crashing in background mode `blender -b -f 1`
+   * for e.g. while it could be fixed, requiring the library at all makes no sense . */
+  if (background) {
+    display_->libdecor_required = false;
+  }
+
   if (display_->libdecor_required) {
     gwl_xdg_decor_system_destroy(display_->xdg_decor);
     display_->xdg_decor = nullptr;
@@ -4200,6 +4209,8 @@ GHOST_SystemWayland::GHOST_SystemWayland() : GHOST_System(), display_(new GWL_Di
 #  endif
       display_destroy(display_);
       throw std::runtime_error("Wayland: unable to find libdecor!");
+
+      use_libdecor = true;
     }
   }
   else {

intern/ghost/intern/GHOST_SystemWayland.h

@@ -84,7 +84,8 @@ struct GWL_Output {
 
 class GHOST_SystemWayland : public GHOST_System {
  public:
-  GHOST_SystemWayland();
+  GHOST_SystemWayland(bool background);
+  GHOST_SystemWayland() : GHOST_SystemWayland(true){};
 
   ~GHOST_SystemWayland() override;