From 31730678c50003d3923ed84fc0a95379893d3a91 Mon Sep 17 00:00:00 2001
From: ispyisail <shane.ringrose@gmail.com>
Date: Mon, 19 Oct 2026 18:27:38 +1300
Subject: [PATCH] Fix a crash on clicking a sheet of a project closed without
 saving

Closing a modified project and choosing Discard left the project in the
project tree. The panel removed its item, but the project still emits
projectInformationsChanged() while it is torn down (setModified()), and
GenericPanel answered by adding the project back, with items for its
sheets. Once the project was freed, a click on one of those sheets
called diagram->showMe() on a freed Diagram: SIGSEGV in
QObjectPrivate::maybeSignalConnected(), the backtrace reported on the
forum (topic 3215).

The panel now stops listening to a project when it is closed, to its
sheets and to its embedded title block collection, before removing its
item.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 sources/elementspanel.cpp                     | 16 ++++-
 tests/qttest/CMakeLists.txt                   |  4 ++
 .../qttest/tst_elementspanelclosedproject.cpp | 72 +++++++++++++++++++
 3 files changed, 89 insertions(+), 3 deletions(-)
 create mode 100644 tests/qttest/tst_elementspanelclosedproject.cpp

diff --git a/sources/elementspanel.cpp b/sources/elementspanel.cpp
index 349f1e9b6..2256de362 100644
--- a/sources/elementspanel.cpp
+++ b/sources/elementspanel.cpp
@@ -422,10 +422,20 @@ void ElementsPanel::projectWasOpened(QETProject *project) {
 	@param project Projet a enlever du panel
 */
 void ElementsPanel::projectWasClosed(QETProject *project) {
-	if (QTreeWidgetItem *item_to_remove = itemForProject(project)) {
-		GenericPanel::deleteItem(item_to_remove);
-		projects_to_display_.remove(project);
+		//Stop listening to the project and its sheets: the project still
+		//emits while it is torn down (setModified() ->
+		//projectInformationsChanged()), which put its item back, with items
+		//for sheets about to be freed
+	if (project) {
+		disconnect(project, nullptr, this, nullptr);
+		disconnect(project->embeddedTitleBlockTemplatesCollection(), nullptr, this, nullptr);
 	}
+	if (QTreeWidgetItem *item_to_remove = itemForProject(project)) {
+		for (QTreeWidgetItem *sheet : childItems(item_to_remove, QET::Diagram))
+			disconnect(valueForItem<Diagram *>(sheet), nullptr, this, nullptr);
+		GenericPanel::deleteItem(item_to_remove);
+	}
+	projects_to_display_.remove(project);
 	emit(panelContentChanged());
 }
 
diff --git a/tests/qttest/CMakeLists.txt b/tests/qttest/CMakeLists.txt
index 25dedbbbe..c2566723f 100644
--- a/tests/qttest/CMakeLists.txt
+++ b/tests/qttest/CMakeLists.txt
@@ -1445,3 +1445,7 @@ if(QET_HAS_SCRIPTING)
     "QET_TEST_BINARY_PATH=\"$<TARGET_FILE:qelectrotech>\""
     "QET_EXAMPLES_DIR=\"${QET_DIR}/examples\"")
 endif()
+
+# Closing a modified project with Discard left it in the project tree, with
+# items for its freed sheets; a click on one crashed (forum topic 3215).
+qet_add_app_test(tst_elementspanelclosedproject tst_elementspanelclosedproject.cpp)
diff --git a/tests/qttest/tst_elementspanelclosedproject.cpp b/tests/qttest/tst_elementspanelclosedproject.cpp
new file mode 100644
index 000000000..b31a1697a
--- /dev/null
+++ b/tests/qttest/tst_elementspanelclosedproject.cpp
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include "qetapptest.h"
+
+#include "elementspanel.h"
+#include "elementspanelwidget.h"
+#include "genericpanel.h"
+#include "projectview.h"
+#include "qetproject.h"
+
+#include <QAbstractButton>
+#include <QMessageBox>
+#include <QPointer>
+#include <QTimer>
+
+// Closing a modified project and choosing Discard left the project in the
+// project tree: the project still emitted projectInformationsChanged() while
+// it was torn down, and the panel added it back, with items for its sheets.
+// A click on one of those sheets then crashed in diagram->showMe() on the
+// freed sheet (forum topic 3215, issue #1548).
+class tst_elementspanelclosedproject : public QObject
+{
+	Q_OBJECT
+
+	private slots:
+		void discardedProjectLeavesTheTree()
+		{
+			QETDiagramEditor *editor = QetAppTest::editor();
+			QVERIFY(editor);
+			auto *panel_widget = editor->findChild<ElementsPanelWidget *>();
+			QVERIFY(panel_widget);
+			ElementsPanel &panel = panel_widget->elementsPanel();
+				// What the app does 250 ms after the panel is first shown.
+			panel.reload();
+
+			QVERIFY(editor->newProject());
+			QPointer<QETProject> project = editor->currentProjectView()->project();
+			project->addNewDiagram();
+			QVERIFY(project->projectWasModified());
+			QTreeWidgetItem *project_item = panel.itemForProject(project);
+			QVERIFY(project_item);
+
+				// Answer "Discard" to "Do you want to save changes?".
+			bool answered = false;
+			QTimer answer;
+			connect(&answer, &QTimer::timeout, this, [&answered]() {
+				if (auto *box = qobject_cast<QMessageBox *>(QApplication::activeModalWidget())) {
+					if (QAbstractButton *discard = box->button(QMessageBox::Discard)) {
+						answered = true;
+						discard->click();
+					}
+				}
+			});
+			answer.start(20);
+
+				// Close it from the project tree's context menu.
+			panel.setCurrentItem(project_item);
+			panel_widget->closeProject();
+			answer.stop();
+			QVERIFY(answered);
+			QTRY_VERIFY(project.isNull());
+
+			for (int i = 0; i < panel.topLevelItemCount(); ++i) {
+				QTreeWidgetItem *item = panel.topLevelItem(i);
+				QVERIFY2(item->type() != QET::Project,
+					qPrintable(QStringLiteral("the closed project is still in the tree: %1").arg(item->text(0))));
+			}
+		}
+};
+
+QET_APP_TEST_MAIN(tst_elementspanelclosedproject)
+
+#include "tst_elementspanelclosedproject.moc"