Dive site: close dive site edit widget when dive site is deleted

The application could be crashed by
1) Create dive site
2) Edit dive site
3) Undo until dive site is removed
4) Continue editing now non-existing dive site

Therefore, hook into the dive-site-deleted signal and if the
currently edited dive site is deleted, close the widget.

When closing the widget, make sure that the potentially
dangling pointer is reset to zero so that there is no
other potential use-after-free bug.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

CHANGELOG.md

@@ -1,3 +1,4 @@
+- Desktop: close dive site widget if dive site is removed by undo
 - Desktop: Don't destroy format of planner notes when editing dive notes [#2265]
 - Map: avoid full map reload when clicking on flag
 - Map: highlight all selected dive sites when clicking on flag

desktop-widgets/locationinformation.cpp

@@ -36,6 +36,7 @@ LocationInformationWidget::LocationInformationWidget(QWidget *parent) : QGroupBo
 	ui.diveSiteCoordinates->installEventFilter(this);
 
 	connect(&diveListNotifier, &DiveListNotifier::diveSiteChanged, this, &LocationInformationWidget::diveSiteChanged);
+	connect(&diveListNotifier, &DiveListNotifier::diveSiteDeleted, this, &LocationInformationWidget::diveSiteDeleted);
 	connect(qPrefUnits::instance(), &qPrefUnits::unit_systemChanged, this, &LocationInformationWidget::unitsChanged);
 	unitsChanged();
 
@@ -178,8 +179,19 @@ static location_t parseGpsText(const QString &text)
 	return { {0}, {0} };
 }
 
+void LocationInformationWidget::diveSiteDeleted(struct dive_site *ds, int)
+{
+	// If the currently edited dive site was removed under our feet, close the widget.
+	// This will reset the dangling pointer.
+	if (ds && ds == diveSite)
+		acceptChanges();
+}
+
 void LocationInformationWidget::acceptChanges()
 {
+	diveSite = nullptr;
+	closeDistance = 0;
+
 	MainWindow::instance()->diveList->setEnabled(true);
 	MainWindow::instance()->setEnabledToolbar(true);
 	MainWindow::instance()->setApplicationState(ApplicationState::Default);

desktop-widgets/locationinformation.h

@@ -34,6 +34,7 @@ public slots:
 private slots:
 	void updateLabels();
 	void diveSiteChanged(struct dive_site *ds, int field);
+	void diveSiteDeleted(struct dive_site *ds, int);
 	void unitsChanged();
 private:
 	void keyPressEvent(QKeyEvent *e) override;