From c00699b15d5f09de4140c8dd02f661fb30d5bbb0 Mon Sep 17 00:00:00 2001
From: marioalexis <mario.passaglia@gmail.com>
Date: Sun, 22 May 2022 02:43:55 -0300
Subject: [PATCH] Gui: Prevent crash when trying to delete pointer to BaseClass

---
 src/Gui/Document.cpp             | 15 ++++++++-------
 src/Gui/View3DInventorViewer.cpp | 14 ++++----------
 src/Gui/WorkbenchManager.cpp     | 26 ++++++++++----------------
 3 files changed, 22 insertions(+), 33 deletions(-)

diff --git a/src/Gui/Document.cpp b/src/Gui/Document.cpp
index 93658f5f6e..198e2041ef 100644
--- a/src/Gui/Document.cpp
+++ b/src/Gui/Document.cpp
@@ -667,21 +667,22 @@ void Document::slotNewObject(const App::DocumentObject& Obj)
                 FC_LOG(Obj.getFullName() << " has no view provider specified");
                 return;
             }
-            Base::BaseClass* base = static_cast<Base::BaseClass*>(
-                    Base::Type::createInstanceByName(cName.c_str(),true));
-            pcProvider = Base::freecad_dynamic_cast<ViewProviderDocumentObject>(base);
+            Base::Type type = Base::Type::getTypeIfDerivedFrom(cName.c_str(), ViewProviderDocumentObject::getClassTypeId(), true);
+            pcProvider = static_cast<ViewProviderDocumentObject*>(type.createInstance());
+            // createInstance could return a null pointer
             if (!pcProvider) {
                 // type not derived from ViewProviderDocumentObject!!!
                 FC_ERR("Invalid view provider type '" << cName << "' for " << Obj.getFullName());
-                delete base;
                 return;
-            } else if (cName!=Obj.getViewProviderName() && !pcProvider->allowOverride(Obj)) {
+            }
+            else if (cName!=Obj.getViewProviderName() && !pcProvider->allowOverride(Obj)) {
                 FC_WARN("View provider type '" << cName << "' does not support " << Obj.getFullName());
-                delete base;
                 pcProvider = nullptr;
                 cName = Obj.getViewProviderName();
-            } else
+            }
+             else {
                 break;
+            }
         }
 
         setModified(true);
diff --git a/src/Gui/View3DInventorViewer.cpp b/src/Gui/View3DInventorViewer.cpp
index f75ecd5639..110212896a 100644
--- a/src/Gui/View3DInventorViewer.cpp
+++ b/src/Gui/View3DInventorViewer.cpp
@@ -1445,18 +1445,13 @@ bool View3DInventorViewer::hasAxisCross(void)
 
 void View3DInventorViewer::setNavigationType(Base::Type t)
 {
-    if (t.isBad())
-        return;
-
     if (this->navigation && this->navigation->getTypeId() == t)
         return; // nothing to do
 
-    Base::BaseClass* base = static_cast<Base::BaseClass*>(t.createInstance());
-    if (!base)
-        return;
-
-    if (!base->getTypeId().isDerivedFrom(NavigationStyle::getClassTypeId())) {
-        delete base;
+    Base::Type type = Base::Type::getTypeIfDerivedFrom(t.getName(), NavigationStyle::getClassTypeId());
+    NavigationStyle* ns = static_cast<NavigationStyle*>(type.createInstance());
+    // createInstance could return a null pointer
+    if (!ns) {
 #if FC_DEBUG
         SoDebugError::postWarning("View3DInventorViewer::setNavigationType",
                                   "Navigation object must be of type NavigationStyle.");
@@ -1464,7 +1459,6 @@ void View3DInventorViewer::setNavigationType(Base::Type t)
         return;
     }
 
-    NavigationStyle* ns = static_cast<NavigationStyle*>(base);
     if (this->navigation) {
         ns->operator = (*this->navigation);
         delete this->navigation;
diff --git a/src/Gui/WorkbenchManager.cpp b/src/Gui/WorkbenchManager.cpp
index 8e5c977785..3da0131fa7 100644
--- a/src/Gui/WorkbenchManager.cpp
+++ b/src/Gui/WorkbenchManager.cpp
@@ -71,23 +71,17 @@ Workbench* WorkbenchManager::createWorkbench (const std::string& name, const std
 
     if (!wb) {
         // try to create an instance now
-        Base::BaseClass* base = static_cast<Base::BaseClass*>
-            (Base::Type::createInstanceByName(className.c_str(),false));
-        if (base) {
-            if (!base->getTypeId().isDerivedFrom(Gui::Workbench::getClassTypeId())) {
-                delete base;
-                std::stringstream str;
-                str << "'" << className << "' not a workbench type" << std::ends;
-                throw Base::TypeError(str.str());
-            }
-
-            wb = static_cast<Workbench*>(base);
-            wb->setName(name);
-            _workbenches[name] = wb;
+        Base::Type type = Base::Type::getTypeIfDerivedFrom(className.c_str(), Workbench::getClassTypeId(), true);
+        wb = static_cast<Workbench*>(type.createInstance());
+        // createInstance could return a null pointer
+        if (!wb) {
+            std::stringstream str;
+            str << "'" << className << "' not a workbench type" << std::ends;
+            throw Base::TypeError(str.str());
         }
-        else
-            Base::Console().Log("WorkbenchManager::createWorkbench(): Can not create "
-                "Workbench instance with type: %s\n",className.c_str());
+
+        wb->setName(name);
+        _workbenches[name] = wb;
     }
 
     return wb;