Add QgsStyle::cleanDefaultStyle() and use it in QgsApplication::exitQ…

…gis()

python/core/auto_generated/symbology/qgsstyle.sip.in

@@ -134,6 +134,7 @@ returns 0 if not found
 Returns default application-wide style
 %End
 
+
     bool tagSymbol( StyleEntity type, const QString &symbol, const QStringList &tags );
 %Docstring
 Tags the symbol with the tags in the list

src/core/qgsapplication.cpp

@@ -47,6 +47,7 @@
 #include "qgs3drendererregistry.h"
 #include "qgslayoutrendercontext.h"
 #include "qgssqliteutils.h"
+#include "qgsstyle.h"
 
 #include "gps/qgsgpsconnectionregistry.h"
 #include "processing/qgsprocessingregistry.h"
@@ -1084,6 +1085,8 @@ void QgsApplication::exitQgis()
 
   delete QgsProviderRegistry::instance();
 
+  QgsStyle::cleanDefaultStyle();
+
   // tear-down GDAL/OGR
   OGRCleanupAll();
   GDALDestroyDriverManager();

src/core/symbology/qgsstyle.cpp

@@ -68,6 +68,11 @@ QgsStyle *QgsStyle::defaultStyle() // static
   return sDefaultStyle;
 }
 
+void QgsStyle::cleanDefaultStyle() // static
+{
+  delete sDefaultStyle;
+  sDefaultStyle = nullptr;
+}
 
 void QgsStyle::clear()
 {

src/core/symbology/qgsstyle.h

@@ -167,6 +167,9 @@ class CORE_EXPORT QgsStyle : public QObject
     //! Returns default application-wide style
     static QgsStyle *defaultStyle();
 
+    //! Deletes the default style. Only to be used by QgsApplication::exitQgis()
+    static void cleanDefaultStyle() SIP_SKIP;
+
     /**
      * Tags the symbol with the tags in the list
      *