Sketcher: fix segmentation fault when using sketch validation dialog after document has been closed

Therefore replace the raw pointer of SketchObject with the template class WeakPtrT. This class will be notified as soon as its handled object will be deleted.

src/Mod/Sketcher/Gui/TaskSketcherValidation.cpp

@@ -107,6 +107,9 @@ void SketcherValidation::changeEvent(QEvent *e)
 
 void SketcherValidation::on_findButton_clicked()
 {
+    if (sketch.expired())
+        return;
+
     double prec = Precision::Confusion();
     bool ok;
     double conv;
@@ -150,6 +153,9 @@ void SketcherValidation::on_findButton_clicked()
 
 void SketcherValidation::on_fixButton_clicked()
 {
+    if (sketch.expired())
+        return;
+
     // undo command open
     App::Document* doc = sketch->getDocument();
     doc->openTransaction("add coincident constraint");
@@ -167,6 +173,9 @@ void SketcherValidation::on_fixButton_clicked()
 
 void SketcherValidation::on_highlightButton_clicked()
 {
+    if (sketch.expired())
+        return;
+
     std::vector<Base::Vector3d> points;
 
     points = sketchAnalyser.getOpenVertices();
@@ -178,6 +187,9 @@ void SketcherValidation::on_highlightButton_clicked()
 
 void SketcherValidation::on_findConstraint_clicked()
 {
+    if (sketch.expired())
+        return;
+
     if (sketch->evaluateConstraints()) {
         QMessageBox::information(this, tr("No invalid constraints"),
             tr("No invalid constraints found"));
@@ -192,12 +204,18 @@ void SketcherValidation::on_findConstraint_clicked()
 
 void SketcherValidation::on_fixConstraint_clicked()
 {
+    if (sketch.expired())
+        return;
+
     sketch->validateConstraints();
     ui->fixConstraint->setEnabled(false);
 }
 
 void SketcherValidation::on_findReversed_clicked()
 {
+    if (sketch.expired())
+        return;
+
     std::vector<Base::Vector3d> points;
     const std::vector<Part::Geometry *>& geom = sketch->getExternalGeometry();
     for (std::size_t i=0; i<geom.size(); i++) {
@@ -241,6 +259,9 @@ void SketcherValidation::on_findReversed_clicked()
 
 void SketcherValidation::on_swapReversed_clicked()
 {
+    if (sketch.expired())
+        return;
+
     App::Document* doc = sketch->getDocument();
     doc->openTransaction("Sketch porting");
 
@@ -255,6 +276,9 @@ void SketcherValidation::on_swapReversed_clicked()
 
 void SketcherValidation::on_orientLockEnable_clicked()
 {
+    if (sketch.expired())
+        return;
+
     App::Document* doc = sketch->getDocument();
     doc->openTransaction("Constraint orientation lock");
 
@@ -269,6 +293,9 @@ void SketcherValidation::on_orientLockEnable_clicked()
 
 void SketcherValidation::on_orientLockDisable_clicked()
 {
+    if (sketch.expired())
+        return;
+
     App::Document* doc = sketch->getDocument();
     doc->openTransaction("Constraint orientation unlock");
 
@@ -284,6 +311,9 @@ void SketcherValidation::on_orientLockDisable_clicked()
 
 void SketcherValidation::on_delConstrExtr_clicked()
 {
+    if (sketch.expired())
+        return;
+
     int reply;
     reply =  QMessageBox::question(this,
                         tr("Delete constraints to external geom."),
@@ -337,21 +367,28 @@ void SketcherValidation::showPoints(const std::vector<Base::Vector3d>& pts)
     }
     coords->point.finishEditing();
 
-    Gui::ViewProvider* vp = Gui::Application::Instance->getViewProvider(sketch);
-    vp->getRoot()->addChild(coincidenceRoot);
+    if (!sketch.expired()) {
+        Gui::ViewProvider* vp = Gui::Application::Instance->getViewProvider(sketch.get());
+        vp->getRoot()->addChild(coincidenceRoot);
+    }
 }
 
 void SketcherValidation::hidePoints()
 {
     if (coincidenceRoot) {
-        Gui::ViewProvider* vp = Gui::Application::Instance->getViewProvider(sketch);
-        vp->getRoot()->removeChild(coincidenceRoot);
-        coincidenceRoot = 0;
+        if (!sketch.expired()) {
+            Gui::ViewProvider* vp = Gui::Application::Instance->getViewProvider(sketch.get());
+            vp->getRoot()->removeChild(coincidenceRoot);
+        }
+        coincidenceRoot = nullptr;
     }
 }
 
 void SketcherValidation::on_findDegenerated_clicked()
 {
+    if (sketch.expired())
+        return;
+
     double prec = Precision::Confusion();
     int count = sketchAnalyser.detectDegeneratedGeometries(prec);
 
@@ -369,6 +406,9 @@ void SketcherValidation::on_findDegenerated_clicked()
 
 void SketcherValidation::on_fixDegenerated_clicked()
 {
+    if (sketch.expired())
+        return;
+
     // undo command open
     App::Document* doc = sketch->getDocument();
     doc->openTransaction("Remove degenerated geometry");

src/Mod/Sketcher/Gui/TaskSketcherValidation.h

@@ -27,6 +27,7 @@
 #include <vector>
 #include <memory>
 #include <Base/Vector3D.h>
+#include <App/DocumentObserver.h>
 #include <Gui/TaskView/TaskDialog.h>
 #include <Mod/Sketcher/App/SketchAnalysis.h>
 
@@ -67,7 +68,7 @@ private:
 
 private:
     std::unique_ptr<Ui_TaskSketcherValidation> ui;
-    Sketcher::SketchObject* sketch;
+    App::WeakPtrT<Sketcher::SketchObject> sketch;
     Sketcher::SketchAnalysis sketchAnalyser;
     SoGroup* coincidenceRoot;
 };