source/blender/editors/space_node/node_draw.cc

@@ -495,8 +495,8 @@ static void node_update_basis_from_declaration(
    * the stack. Each panel expects a number of items to be added, after which the panel is removed
    * from the stack again. */
   struct PanelUpdate {
-    /* How many items still to add. */
-    int remaining_items;
+    /* How many declarations still to add. */
+    int remaining_decls;
     /* True if the panel or its parent is collapsed. */
     bool is_collapsed;
     /* Location data, needed to finalize the panel when all items have been added. */
@@ -508,8 +508,8 @@ static void node_update_basis_from_declaration(
     bool is_parent_collapsed = false;
     if (PanelUpdate *parent_update = panel_updates.is_empty() ? nullptr : &panel_updates.peek()) {
       /* Adding an item to the parent panel, will be popped when reaching 0. */
-      BLI_assert(parent_update->remaining_items > 0);
-      --parent_update->remaining_items;
+      BLI_assert(parent_update->remaining_decls > 0);
+      --parent_update->remaining_decls;
       is_parent_collapsed = parent_update->is_collapsed;
     }
 
@@ -531,7 +531,7 @@ static void node_update_basis_from_declaration(
           current_panel_state->flag, is_parent_collapsed, NODE_PANEL_PARENT_COLLAPSED);
       /* New top panel is collapsed if self or parent is collapsed. */
       const bool is_collapsed = is_parent_collapsed || current_panel_state->is_collapsed();
-      panel_updates.push({panel_decl->num_items, is_collapsed, current_panel_runtime});
+      panel_updates.push({panel_decl->num_child_decls, is_collapsed, current_panel_runtime});
 
       /* Round the socket location to stop it from jiggling. */
       current_panel_runtime->location_y = round(locy + NODE_DYS);
@@ -578,7 +578,7 @@ static void node_update_basis_from_declaration(
     /* Close parent panels that have all items added. */
     while (!panel_updates.is_empty()) {
       PanelUpdate &top_panel = panel_updates.peek();
-      if (top_panel.remaining_items > 0) {
+      if (top_panel.remaining_decls > 0) {
         /* Incomplete panel, continue adding items. */
         break;
       }

source/blender/nodes/NOD_node_declaration.hh

@@ -497,7 +497,7 @@ class PanelDeclaration : public ItemDeclaration {
   std::string description;
   std::string translation_context;
   bool default_collapsed = false;
-  int num_items = 0;
+  int num_child_decls = 0;
 
  private:
   friend NodeDeclarationBuilder;

source/blender/nodes/intern/node_common.cc

@@ -315,6 +315,32 @@ static SocketDeclarationPtr declaration_for_interface_socket(
   return dst;
 }
 
+/* Socket items can be both input and output, generating 2 declarations for 1 item. Count the
+ * actual declarations generated by panel content to get the true size for UI drawing. */
+static int count_panel_declaration_children(const bNodeTreeInterfacePanel &io_panel)
+{
+  int num_child_decls = 0;
+  io_panel.foreach_item([&](const bNodeTreeInterfaceItem &item) {
+    switch (item.item_type) {
+      case NODE_INTERFACE_PANEL:
+        num_child_decls++;
+        break;
+      case NODE_INTERFACE_SOCKET:
+        const bNodeTreeInterfaceSocket &socket =
+            reinterpret_cast<const bNodeTreeInterfaceSocket &>(item);
+        if (socket.flag & NODE_INTERFACE_SOCKET_INPUT) {
+          num_child_decls++;
+        }
+        if (socket.flag & NODE_INTERFACE_SOCKET_OUTPUT) {
+          num_child_decls++;
+        }
+        break;
+    }
+    return true;
+  });
+  return num_child_decls;
+}
+
 static PanelDeclarationPtr declaration_for_interface_panel(const bNodeTree & /*ntree*/,
                                                            const bNodeTreeInterfacePanel &io_panel)
 {
@@ -327,7 +353,7 @@ static PanelDeclarationPtr declaration_for_interface_panel(const bNodeTree & /*n
   dst->name = io_panel.name ? io_panel.name : "";
   dst->description = io_panel.description ? io_panel.description : "";
   dst->default_collapsed = (io_panel.flag & NODE_INTERFACE_PANEL_DEFAULT_CLOSED);
-  dst->num_items = io_panel.items_num;
+  dst->num_child_decls = count_panel_declaration_children(io_panel);
   return dst;
 }