fix infinite recursion in case of non-DAG documents

src/Base/Tools.h

@@ -165,6 +165,20 @@ private:
 
 // ----------------------------------------------------------------------------
 
+class StateLocker
+{
+public:
+    StateLocker(bool& flag, bool st = true) : lock(flag), state(st)
+    { lock = state; }
+    ~StateLocker()
+    { lock = !state; }
+private:
+    bool& lock;
+    bool state;
+};
+
+// ----------------------------------------------------------------------------
+
 class ConnectionBlocker {
     typedef boost::BOOST_SIGNALS_NAMESPACE::connection Connection;
     bool b;

src/Gui/ViewProviderGroupExtension.cpp

@@ -32,6 +32,7 @@
 #include "Command.h"
 #include "Application.h"
 #include "Document.h"
+#include <Base/Tools.h>
 #include <App/Document.h>
 #include <App/DocumentObject.h>
 #include <App/GroupExtension.h>
@@ -43,7 +44,7 @@ using namespace Gui;
 
 EXTENSION_PROPERTY_SOURCE(Gui::ViewProviderGroupExtension, Gui::ViewProviderExtension)
 
-ViewProviderGroupExtension::ViewProviderGroupExtension()  : visible(false)
+ViewProviderGroupExtension::ViewProviderGroupExtension()  : visible(false), guard(false)
 {
     initExtensionType(ViewProviderGroupExtension::getExtensionClassTypeId());
 }
@@ -116,6 +117,11 @@ std::vector< App::DocumentObject* > ViewProviderGroupExtension::extensionClaimCh
 
 void ViewProviderGroupExtension::extensionShow(void) {
 
+    // avoid possible infinite recursion
+    if (guard)
+        return;
+    Base::StateLocker lock(guard);
+
     // when reading the Visibility property from file then do not hide the
     // objects of this group because they have stored their visibility status, too
     if (!getExtendedViewProvider()->isRestoring() && !this->visible) {
@@ -136,6 +142,11 @@ void ViewProviderGroupExtension::extensionShow(void) {
 
 void ViewProviderGroupExtension::extensionHide(void) {
 
+    // avoid possible infinite recursion
+    if (guard)
+        return;
+    Base::StateLocker lock(guard);
+
     // when reading the Visibility property from file then do not hide the
     // objects of this group because they have stored their visibility status, too
     if (!getExtendedViewProvider()->isRestoring() && this->visible) {

src/Gui/ViewProviderGroupExtension.h

@@ -54,6 +54,7 @@ public:
 
 private:
     bool visible; // helper variable
+    bool guard;
     std::vector<ViewProvider*> nodes;
 };