Fix problem when really old elements are added to a new project. These elements do not have an uuid for each terminal. So when exporting, save an unique ID into the terminal. So the conductors know to which terminal they must be connected

sources/diagram.cpp

@@ -1864,6 +1864,28 @@ void Diagram::changeZValue(QET::DepthOption option)
 		delete undo;
 }
 
+int Diagram::uniqueTerminalID() const
+{
+    for (int i=1; i < 10000; i++) {
+        bool found = false;
+        for (auto element: elements()) {
+            for (auto terminal: element->terminals()) {
+                if (terminal->ID() == i) {
+                    found = true;
+                    break;
+                }
+            }
+            if (found) {
+                break;
+            }
+        }
+
+        if (!found)
+            return i;
+    }
+    return -1;
+}
+
 /**
 	@brief Diagram::loadElmtFolioSeq
 	This class loads all folio sequential variables related

sources/diagram.h

@@ -257,6 +257,13 @@ class Diagram : public QGraphicsScene
 					   NumerotationContext *nc);
 		void changeZValue(QET::DepthOption option);
 
+		/*!
+		 * \brief uniqueTerminalID
+		 * Determines a new unique Terminal ID
+		 * This is used only for legacy purpose
+		 */
+        int uniqueTerminalID() const;
+
 	public slots:
 		void adjustSceneRect ();
 		void titleChanged(const QString &);

sources/qetgraphicsitem/element.cpp

@@ -944,8 +944,15 @@ QDomElement Element::toXml(
 		QDomElement terminal = t -> toXml(document);
 		if (t->ID() > 0) {
 			// for backward compatibility
+            // Terminal was loaded during loading an old project. So the terminal has a valid id
 			terminal.setAttribute("id", t->ID()); // for backward compatibility
-		}
+        } else if (t->uuid().isNull()) {
+          // for backward compatibility
+          // An old element with no uuid on the terminals was added to the project.
+          // give it an id
+          t->setID(t->diagram()->uniqueTerminalID());
+          terminal.setAttribute("id", t->ID());
+        }
 		xml_terminals.appendChild(terminal);
 	}
 	element.appendChild(xml_terminals);