Geometry Nodes: add utility to show debug messages in node editor

This is only meant to be used for development purposes for now,
not to show warnings to the user.

Differential Revision: https://developer.blender.org/D13348

source/blender/nodes/intern/geometry_nodes_eval_log.cc

@@ -72,6 +72,11 @@ ModifierLog::ModifierLog(GeoLogger &logger)
                                                        node_with_exec_time.node);
       node_log.exec_time_ = node_with_exec_time.exec_time;
     }
+
+    for (NodeWithDebugMessage &debug_message : local_logger.node_debug_messages_) {
+      NodeLog &node_log = this->lookup_or_add_node_log(log_by_tree_context, debug_message.node);
+      node_log.debug_messages_.append(debug_message.message);
+    }
   }
 }
 
@@ -484,4 +489,13 @@ void LocalGeoLogger::log_execution_time(DNode node, std::chrono::microseconds ex
   node_exec_times_.append({node, exec_time});
 }
 
+/**
+ * Log a message that will be displayed in the node editor next to the node. This should only be
+ * used for debugging purposes and not to display information to users.
+ */
+void LocalGeoLogger::log_debug_message(DNode node, std::string message)
+{
+  node_debug_messages_.append({node, std::move(message)});
+}
+
 }  // namespace blender::nodes::geometry_nodes_eval_log