# --- T2-COPYRIGHT-BEGIN ---
# t2/package/*/firefox/hotfix-webrender-swgl-x11.patch
# Copyright (C) 2026 The T2 SDE Project
# SPDX-License-Identifier: GPL-2.0 or patched project license
# --- T2-COPYRIGHT-END ---

# Firefox 154 dropped both guards from GtkCompositorWidget::GetNativeLayerRoot(),
# which in 153 read:
#
#   if (!mNativeLayerRoot && gfx::gfxVars::UseWebRenderCompositor() &&
#       WaylandDisplayGet()->GetFractionalScaleManager()) {
#
# The function builds a NativeLayerRootWayland out of the MozContainer's
# wl_surface, so it only ever makes sense in a Wayland session. CompositorOGL's
# constructor calls GetNativeLayerRoot() unconditionally, and that constructor is
# reached on X11 too as soon as gfx.webrender.software.opengl is true
# (RenderCompositor::Create -> RenderCompositorLayersSWGL::Create ->
# RenderCompositorOGLSWGL::Create -> new CompositorOGL). On an X11 session there
# is no wl_surface, and the parent process segfaults on the Renderer thread
# before the first paint.
#
# Restore the UseWebRenderCompositor() guard: gfxPlatformGtk force-disables
# Feature::WEBRENDER_COMPOSITOR when !IsWaylandDisplay(), so this is false on X11
# and GetNativeLayerRoot() again returns nullptr there, as CompositorOGL expects.
# The FractionalScaleManager() condition is deliberately not restored - that part
# of the 153 guard belongs to the pre-WaylandSurface code.

--- firefox-154.0.1/widget/gtk/GtkCompositorWidget.cpp.vanilla
+++ firefox-154.0.1/widget/gtk/GtkCompositorWidget.cpp
@@ -144,7 +144,10 @@
 
 #ifdef MOZ_WAYLAND
 mozilla::layers::NativeLayerRoot* GtkCompositorWidget::GetNativeLayerRoot() {
-  if (!mNativeLayerRoot) {
+  // The native layer root is a Wayland-only construct. WEBRENDER_COMPOSITOR is
+  // force-disabled when !IsWaylandDisplay(), so this also keeps X11 sessions
+  // out, where MOZ_WL_SURFACE() has nothing to hand us and we would crash.
+  if (!mNativeLayerRoot && gfx::gfxVars::UseWebRenderCompositor()) {
     LOG("GtkCompositorWidget::GetNativeLayerRoot [%p] create",
         (void*)mWidget.get());
     MOZ_ASSERT(mWidget && mWidget->GetMozContainer());