Fix a leak and a crash in designerv5.7.1

This change downports the
56ac0c12ab5e7269e16bcc1248e4241302d91d09
change to the 5.7.1 branch in order to
have a chance for releasing Qt Creator 4.2
with a fix. The crash doesn't appear in
the standalone Designer, it only appears
in the Designer plugin of Qt Creator during reload.
There is no other way to fix that crash
outside of Qt.

Task-number: QTCREATORBUG-17150
Change-Id: Ide521677a1526d3de862d0d8e283531a67b2a7a8
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
(cherry picked from commit 56ac0c12ab5e7269e16bcc1248e4241302d91d09)

1 files changed, 57 insertions, 4 deletions

diff --git a/src/designer/src/lib/shared/formwindowbase.cpp b/src/designer/src/lib/shared/formwindowbase.cpp
index e702d777a..d8f422a0a 100644
--- a/src/designer/src/lib/shared/formwindowbase.cpp
+++ b/src/designer/src/lib/shared/formwindowbase.cpp
@@ -47,6 +47,7 @@
 
 #include <QtCore/qdebug.h>
 #include <QtCore/QList>
+#include <QtCore/QSet>
 #include <QtCore/QTimer>
 #include <QtWidgets/QMenu>
 #include <QtWidgets/QListWidget>
@@ -112,6 +113,15 @@ FormWindowBase::FormWindowBase(QDesignerFormEditorInterface *core, QWidget *pare
 
 FormWindowBase::~FormWindowBase()
 {
+    QSet<QDesignerPropertySheet *> sheets = m_d->m_reloadableResources.keys().toSet();
+    sheets |= m_d->m_reloadablePropertySheets.keys().toSet();
+
+    m_d->m_reloadableResources.clear();
+    m_d->m_reloadablePropertySheets.clear();
+
+    for (QDesignerPropertySheet *sheet : sheets)
+        disconnectSheet(sheet);
+
     delete m_d;
 }
 
@@ -137,14 +147,17 @@ void FormWindowBase::setResourceSet(QtResourceSet *resourceSet)
 
 void FormWindowBase::addReloadableProperty(QDesignerPropertySheet *sheet, int index)
 {
+    connectSheet(sheet);
     m_d->m_reloadableResources[sheet][index] = true;
 }
 
 void FormWindowBase::removeReloadableProperty(QDesignerPropertySheet *sheet, int index)
 {
     m_d->m_reloadableResources[sheet].remove(index);
-    if (m_d->m_reloadableResources[sheet].count() == 0)
+    if (!m_d->m_reloadableResources[sheet].count()) {
         m_d->m_reloadableResources.remove(sheet);
+        disconnectSheet(sheet);
+    }
 }
 
 void FormWindowBase::addReloadablePropertySheet(QDesignerPropertySheet *sheet, QObject *object)
@@ -152,13 +165,53 @@ void FormWindowBase::addReloadablePropertySheet(QDesignerPropertySheet *sheet, Q
     if (qobject_cast<QTreeWidget *>(object) ||
             qobject_cast<QTableWidget *>(object) ||
             qobject_cast<QListWidget *>(object) ||
-            qobject_cast<QComboBox *>(object))
+            qobject_cast<QComboBox *>(object)) {
+        connectSheet(sheet);
         m_d->m_reloadablePropertySheets[sheet] = object;
+    }
 }
 
-void FormWindowBase::removeReloadablePropertySheet(QDesignerPropertySheet *sheet)
+void FormWindowBase::connectSheet(QDesignerPropertySheet *sheet)
 {
-    m_d->m_reloadablePropertySheets.remove(sheet);
+    if (m_d->m_reloadableResources.contains(sheet)
+            || m_d->m_reloadablePropertySheets.contains(sheet)) {
+        // already connected
+        return;
+    }
+    connect(sheet, &QObject::destroyed, this, &FormWindowBase::sheetDestroyed);
+}
+
+void FormWindowBase::disconnectSheet(QDesignerPropertySheet *sheet)
+{
+    if (m_d->m_reloadableResources.contains(sheet)
+            || m_d->m_reloadablePropertySheets.contains(sheet)) {
+        // still need to be connected
+        return;
+    }
+    disconnect(sheet, &QObject::destroyed, this, &FormWindowBase::sheetDestroyed);
+}
+
+void FormWindowBase::sheetDestroyed(QObject *object)
+{
+    // qobject_cast<QDesignerPropertySheet *>(object)
+    // will fail since the destructor of QDesignerPropertySheet
+    // has already finished
+
+    for (auto it = m_d->m_reloadableResources.begin();
+         it != m_d->m_reloadableResources.end(); ++it) {
+        if (it.key() == object) {
+            m_d->m_reloadableResources.erase(it);
+            break;
+        }
+    }
+
+    for (auto it = m_d->m_reloadablePropertySheets.begin();
+         it != m_d->m_reloadablePropertySheets.end(); ++it) {
+        if (it.key() == object) {
+            m_d->m_reloadablePropertySheets.erase(it);
+            break;
+        }
+    }
 }
 
 void FormWindowBase::reloadProperties()