From a7853a088cb6c1137a5ffaa75cabcf2f05f017e4 Mon Sep 17 00:00:00 2001
From: Abdullah Tahiri <abdullah.tahiri.yo@gmail.com>
Date: Sat, 18 Mar 2023 09:41:58 +0100
Subject: [PATCH] ElementWidget: remove unnecesary element pointer

================================================

This should fix this (I cannot reproduce it):
https://forum.freecad.org/viewtopic.php?p=667579#p667579

Lately I added the geometry pointer to the item. This has indeed
the potential for an already deleted pointer being accessed.

This PR removes the geometry pointer from the item and relies on the
ViewProvider to indirectly access an updated pointer.
---
 src/Mod/Sketcher/Gui/TaskSketcherElements.cpp | 30 +++++++++++++------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/src/Mod/Sketcher/Gui/TaskSketcherElements.cpp b/src/Mod/Sketcher/Gui/TaskSketcherElements.cpp
index 1eb88e910c..dc8e52e1f4 100644
--- a/src/Mod/Sketcher/Gui/TaskSketcherElements.cpp
+++ b/src/Mod/Sketcher/Gui/TaskSketcherElements.cpp
@@ -117,7 +117,7 @@ class ElementItem : public QListWidgetItem
     };
 
     ElementItem(int elementnr, int startingVertex, int midVertex, int endVertex,
-        Base::Type geometryType, GeometryState state, const QString & lab, const Part::Geometry * geo) :
+        Base::Type geometryType, GeometryState state, const QString & lab, ViewProviderSketch *sketchView) :
         ElementNbr(elementnr)
         , StartingVertex(startingVertex)
         , MidVertex(midVertex)
@@ -132,7 +132,7 @@ class ElementItem : public QListWidgetItem
         , hovered(SubElementType::none)
         , rightClicked(false)
         , label(lab)
-        , geo(geo)
+        , sketchView(sketchView)
     {
 
     }
@@ -141,9 +141,20 @@ class ElementItem : public QListWidgetItem
     }
 
     bool isVisible() {
-        auto layer = getSafeGeomLayerId(geo);
 
-        return layer != static_cast<unsigned int>(Layer::Hidden);
+        if(State != GeometryState::External) {
+            const auto geo = sketchView->getSketchObject()->getGeometry(ElementNbr);
+            if(geo) {
+                auto layer = getSafeGeomLayerId(geo);
+
+                return layer != static_cast<unsigned int>(Layer::Hidden);
+            }
+        }
+
+        // 1. external geometry currently is always visible.
+        // 2. if internal and ElementNbr is out of range, the element
+        // needs to be updated and the return value is not important.
+        return true;
     }
 
     int ElementNbr;
@@ -166,7 +177,8 @@ class ElementItem : public QListWidgetItem
 
     QString label;
 
-    const Part::Geometry * geo;
+    private:
+    ViewProviderSketch *sketchView;
 };
 
 class ElementFilterList : public QListWidget
@@ -1369,8 +1381,8 @@ void TaskSketcherElements::slotElementsChanged(void)
             (isNamingBoxChecked ?
                 (tr("Other") + IdInformation()) +
                 (construction ? (QString::fromLatin1("-") + tr("Construction")) : (internalAligned ? (QString::fromLatin1("-") + tr("Internal")) : QString::fromLatin1(""))) :
-                (QString::fromLatin1("%1-").arg(i) + tr("Other")))
-            , (*it) // geometry
+                (QString::fromLatin1("%1-").arg(i) + tr("Other"))),
+            sketchView
         );
 
         ui->listWidgetElements->addItem(itemN);
@@ -1461,8 +1473,8 @@ void TaskSketcherElements::slotElementsChanged(void)
                     (QString::fromLatin1("%1-").arg(i - 2) + tr("BSpline"))) :
                 (isNamingBoxChecked ?
                     (tr("Other") + linkname) :
-                    (QString::fromLatin1("%1-").arg(i - 2) + tr("Other")))
-                , (*it) // geometry
+                    (QString::fromLatin1("%1-").arg(i - 2) + tr("Other"))),
+                sketchView
             );
 
             ui->listWidgetElements->addItem(itemN);