bugfix: wlr layer shell surface are guaranteed to have a nonzero size

src/server/frontend_wayland/layer_shell_v1.cpp

@@ -409,7 +409,7 @@ auto mf::LayerSurfaceV1::vert_padding(Anchors const& anchors, Margin const& marg
 
 auto mf::LayerSurfaceV1::unpadded_requested_size() const -> geom::Size
 {
-    auto size = requested_window_size().value_or(current_size());
+    auto size = requested_window_size().value_or(current_size().value_or(geom::Size(640, 480)));
     size.width -= horiz_padding(anchors.committed(), margin.committed());
     size.height -= vert_padding(anchors.committed(), margin.committed());
     return size;

src/server/frontend_wayland/window_wl_surface_role.cpp

@@ -284,26 +284,30 @@ void mf::WindowWlSurfaceRole::remove_state_now(MirWindowState state)
 
 auto mf::WindowWlSurfaceRole::pending_size() const -> geom::Size
 {
-    auto size = current_size();
+    auto size = current_size().value_or(geom::Size{0, 0});
     if (pending_explicit_width)
         size.width = pending_explicit_width.value();
     if (pending_explicit_height)
         size.height = pending_explicit_height.value();
     return size;
 }
 
-auto mf::WindowWlSurfaceRole::current_size() const -> geom::Size
+auto mf::WindowWlSurfaceRole::current_size() const -> std::optional<geom::Size>
 {
     if (surface)
     {
-        auto const buffer_size = surface.value().buffer_size().value_or(geom::Size{});
-
-        return {
-            committed_width_set_explicitly.value_or(buffer_size.width),
-            committed_height_set_explicitly.value_or(buffer_size.height)};
+        auto buffer_size = surface.value().buffer_size();
+        if (committed_width_set_explicitly || committed_height_set_explicitly)
+        {
+            return geom::Size{
+                committed_width_set_explicitly.value_or(buffer_size ? buffer_size.value().width : geom::Width{0}),
+                committed_height_set_explicitly.value_or(buffer_size ? buffer_size.value().height : geom::Height{0})};
+        }
+        else
+            return buffer_size;
     }
 
-    return geom::Size{0, 0};
+    return std::nullopt;
 }
 
 auto mf::WindowWlSurfaceRole::requested_window_size() const -> std::optional<geom::Size>

src/server/frontend_wayland/window_wl_surface_role.h

@@ -119,8 +119,8 @@ class WindowWlSurfaceRole
     /// The size the window will be after the next commit
     auto pending_size() const -> geometry::Size;
 
-    /// The size the window currently is (the committed size, or a reasonable default if it has never committed)
-    auto current_size() const -> geometry::Size;
+    /// The size the window currently is (the committed size, or std::nullopt if it has never committed)
+    auto current_size() const -> std::optional<geometry::Size>;
 
     /// Window size requested by Mir
     auto requested_window_size() const -> std::optional<geometry::Size>;