Don't delete QgsAttributeDialog too early. Fixes #15737

(cherry picked from commit 9ecdf61)

src/app/qgsfeatureaction.cpp

@@ -98,7 +98,9 @@ bool QgsFeatureAction::viewFeatureForm( QgsHighlight *h )
 
   QgsAttributeDialog *dialog = newDialog( true );
   dialog->setHighlight( h );
-  dialog->show(); // will also delete the dialog on close (show() is overridden)
+  // delete the dialog when it is closed
+  dialog->setAttribute( Qt::WA_DeleteOnClose );
+  dialog->show();
 
   return true;
 }
@@ -108,24 +110,29 @@ bool QgsFeatureAction::editFeature( bool showModal )
   if ( !mLayer )
     return false;
 
-  QgsAttributeDialog *dialog = newDialog( false );
-
-  if ( !mFeature->isValid() )
-    dialog->setIsAddDialog( true );
-
   if ( showModal )
   {
-    dialog->setAttribute( Qt::WA_DeleteOnClose );
-    int rv = dialog->exec();
+    QScopedPointer<QgsAttributeDialog> dialog( newDialog( false ) );
+
+    if ( !mFeature->isValid() )
+      dialog->setIsAddDialog( true );
 
+    int rv = dialog->exec();
     mFeature->setAttributes( dialog->feature()->attributes() );
     return rv;
   }
   else
   {
-    dialog->show(); // will also delete the dialog on close (show() is overridden)
-  }
+    QgsAttributeDialog* dialog = newDialog( false );
+
+    if ( !mFeature->isValid() )
+      dialog->setIsAddDialog( true );
 
+    // delete the dialog when it is closed
+    dialog->setAttribute( Qt::WA_DeleteOnClose );
+    dialog->show();
+  }
+
   return true;
 }
 
@@ -193,6 +200,8 @@ bool QgsFeatureAction::addFeature( const QgsAttributeMap& defaultAttributes, boo
   else
   {
     QgsAttributeDialog *dialog = newDialog( false );
+    // delete the dialog when it is closed
+    dialog->setAttribute( Qt::WA_DeleteOnClose );
     dialog->setIsAddDialog( true );
     dialog->setEditCommandMessage( text() );
 
@@ -201,12 +210,11 @@ bool QgsFeatureAction::addFeature( const QgsAttributeMap& defaultAttributes, boo
     if ( !showModal )
     {
       setParent( dialog ); // keep dialog until the dialog is closed and destructed
-      dialog->show(); // will also delete the dialog on close (show() is overridden)
+      dialog->show();
       mFeature = nullptr;
       return true;
     }
 
-    dialog->setAttribute( Qt::WA_DeleteOnClose );
     dialog->exec();
   }
 

src/gui/qgsattributedialog.cpp

@@ -87,11 +87,8 @@ void QgsAttributeDialog::accept()
   QDialog::accept();
 }
 
-void QgsAttributeDialog::show( bool autoDelete )
+void QgsAttributeDialog::show()
 {
-  if ( autoDelete )
-    setAttribute( Qt::WA_DeleteOnClose );
-
   QDialog::show();
   raise();
   activateWindow();

src/gui/qgsattributedialog.h

@@ -130,9 +130,8 @@ class GUI_EXPORT QgsAttributeDialog : public QDialog
   public slots:
     void accept() override;
 
-    //! Show the dialog non-blocking. Reparents this dialog to be a child of the dialog form and is deleted when
-    //! closed.
-    void show( bool autoDelete = true );
+    //! Show the dialog non-blocking. Reparents this dialog to be a child of the dialog form
+    void show();
 
   private:
     void init( QgsVectorLayer* layer, QgsFeature* feature, const QgsAttributeEditorContext& context );