Fix ownership of algorithm instance used by processing dialog

(cherry picked from commit a350b42)

python/gui/auto_generated/processing/qgsprocessingalgorithmdialogbase.sip.in

@@ -38,11 +38,14 @@ Base class for processing algorithm dialogs.
 %Docstring
 Constructor for QgsProcessingAlgorithmDialogBase.
 %End
+    ~QgsProcessingAlgorithmDialogBase();
 
-    void setAlgorithm( QgsProcessingAlgorithm *algorithm );
+    void setAlgorithm( QgsProcessingAlgorithm *algorithm /Transfer/ );
 %Docstring
 Sets the ``algorithm`` to run in the dialog.
 
+Ownership of the algorithm instance is transferred to the dialog.
+
 .. seealso:: :py:func:`algorithm`
 %End
 

src/gui/processing/qgsprocessingalgorithmdialogbase.cpp

@@ -119,9 +119,11 @@ QgsProcessingAlgorithmDialogBase::QgsProcessingAlgorithmDialogBase( QWidget *par
   connect( QgsApplication::taskManager(), &QgsTaskManager::taskTriggered, this, &QgsProcessingAlgorithmDialogBase::taskTriggered );
 }
 
+QgsProcessingAlgorithmDialogBase::~QgsProcessingAlgorithmDialogBase() = default;
+
 void QgsProcessingAlgorithmDialogBase::setAlgorithm( QgsProcessingAlgorithm *algorithm )
 {
-  mAlgorithm = algorithm;
+  mAlgorithm.reset( algorithm );
   QString title;
   if ( ( QgsGui::higFlags() & QgsGui::HigDialogTitleIsTitleCase ) && !( algorithm->flags() & QgsProcessingAlgorithm::FlagDisplayNameIsLiteral ) )
   {
@@ -156,7 +158,7 @@ void QgsProcessingAlgorithmDialogBase::setAlgorithm( QgsProcessingAlgorithm *alg
 
 QgsProcessingAlgorithm *QgsProcessingAlgorithmDialogBase::algorithm()
 {
-  return mAlgorithm;
+  return mAlgorithm.get();
 }
 
 void QgsProcessingAlgorithmDialogBase::setMainWidget( QWidget *widget )

src/gui/processing/qgsprocessingalgorithmdialogbase.h

@@ -99,12 +99,16 @@ class GUI_EXPORT QgsProcessingAlgorithmDialogBase : public QDialog, private Ui::
      * Constructor for QgsProcessingAlgorithmDialogBase.
      */
     QgsProcessingAlgorithmDialogBase( QWidget *parent SIP_TRANSFERTHIS = nullptr, Qt::WindowFlags flags = nullptr );
+    ~QgsProcessingAlgorithmDialogBase() override;
 
     /**
      * Sets the \a algorithm to run in the dialog.
+     *
+     * Ownership of the algorithm instance is transferred to the dialog.
+     *
      * \see algorithm()
      */
-    void setAlgorithm( QgsProcessingAlgorithm *algorithm );
+    void setAlgorithm( QgsProcessingAlgorithm *algorithm SIP_TRANSFER );
 
     /**
      * Returns the algorithm running in the dialog.
@@ -333,7 +337,7 @@ class GUI_EXPORT QgsProcessingAlgorithmDialogBase : public QDialog, private Ui::
     bool mExecuted = false;
     QVariantMap mResults;
     QWidget *mMainWidget = nullptr;
-    QgsProcessingAlgorithm *mAlgorithm = nullptr;
+    std::unique_ptr< QgsProcessingAlgorithm > mAlgorithm;
     QgsProcessingAlgRunnerTask *mAlgorithmTask = nullptr;
 
     bool mHelpCollapsed = false;