From a2efab04852cd51433e7cc4e8cd111ba37ef561d Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Mon, 11 Jul 2016 13:10:41 +1000
Subject: [PATCH] Make QgsVectorLayerImport use QgsCoordinateReferenceSystem
 references, not pointers

---
 doc/api_break.dox                             |  9 ++++
 python/core/qgsvectorlayerimport.sip          | 41 +++++++++++++++----
 src/core/qgsvectorlayerimport.cpp             | 16 ++++----
 src/core/qgsvectorlayerimport.h               | 31 ++++++++++++--
 src/gui/qgsnewvectorlayerdialog.cpp           |  4 +-
 .../ui/qgsgeometrycheckerresulttab.cpp        |  4 +-
 src/providers/db2/qgsdb2dataitems.cpp         |  2 +-
 src/providers/db2/qgsdb2provider.cpp          | 23 +++++------
 src/providers/db2/qgsdb2provider.h            |  2 +-
 src/providers/mssql/qgsmssqldataitems.cpp     |  2 +-
 src/providers/mssql/qgsmssqlprovider.cpp      | 31 +++++++-------
 src/providers/mssql/qgsmssqlprovider.h        |  2 +-
 src/providers/ogr/qgsogrprovider.cpp          | 25 ++++++-----
 src/providers/ogr/qgsogrprovider.h            |  2 +-
 .../postgres/qgspostgresdataitems.cpp         |  2 +-
 .../postgres/qgspostgresprovider.cpp          | 21 +++++-----
 src/providers/postgres/qgspostgresprovider.h  |  2 +-
 .../spatialite/qgsspatialitedataitems.cpp     |  2 +-
 .../spatialite/qgsspatialiteprovider.cpp      | 21 +++++-----
 .../spatialite/qgsspatialiteprovider.h        |  2 +-
 20 files changed, 147 insertions(+), 97 deletions(-)

diff --git a/doc/api_break.dox b/doc/api_break.dox
index 93cbe3ea41d..614514e2d71 100644
--- a/doc/api_break.dox
+++ b/doc/api_break.dox
@@ -41,6 +41,15 @@ objects are implicitly shared, returning a copy helps simplify and make code mor
 only affects third party c++ providers, and does not affect PyQGIS scripts.</li>
 </ul>
 
+\subsection qgis_api_break_3_0_QgsVectorLayerImport QgsVectorLayerImport
+
+<ul>
+<li>QgsVectorLayerImport now takes references instead of pointers to QgsCoordinateReferenceSystem objects. Since
+QgsCoordinateReferenceSystem is now implicitly shared, using references to QgsCoordinateReferenceSystem rather than
+pointers makes for more robust, safer code. Use an invalid (default constructed) QgsCoordinateReferenceSystem
+in code which previously passed a null pointer to QgsVectorLayerImport.</li>
+</ul>
+
 \subsection qgis_api_break_3_0_QgsVectorFileWriter QgsVectorFileWriter
 
 <ul>
diff --git a/python/core/qgsvectorlayerimport.sip b/python/core/qgsvectorlayerimport.sip
index 8ff090f1230..cfad372e923 100644
--- a/python/core/qgsvectorlayerimport.sip
+++ b/python/core/qgsvectorlayerimport.sip
@@ -31,27 +31,50 @@ class QProgressDialog;
       ErrUserCancelled, /*!< User cancelled the import*/
     };
 
-    /** Write contents of vector layer to a different datasource */
+     /**
+     * Writes the contents of vector layer to a different datasource.
+     * @param layer source layer
+     * @param uri URI for destination data source
+     * @param providerKey string key for destination data provider
+     * @param destCRS destination CRS, or an invalid (default constructed) CRS if
+     * not available
+     * @param onlySelected set to true to export only selected features
+     * @param errorMessage if non-null, will be set to any error messages
+     * @param skipAttributeCreation set to true to skip exporting feature attributes
+     * @param options optional provider dataset options
+     * @param progress optional progress dialog to show progress of export
+     * @returns NoError for a successful export, or encountered error
+     */
     static ImportError importLayer( QgsVectorLayer* layer,
                                     const QString& uri,
                                     const QString& providerKey,
-                                    const QgsCoordinateReferenceSystem *destCRS,
+                                    const QgsCoordinateReferenceSystem& destCRS,
                                     bool onlySelected = false,
-                                    QString *errorMessage /Out/ = 0,
+                                    QString *errorMessage /Out/ = nullptr,
                                     bool skipAttributeCreation = false,
-                                    QMap<QString, QVariant> *options = 0,
-                                    QProgressDialog *progress = 0
+                                    QMap<QString, QVariant> *options = nullptr,
+                                    QProgressDialog *progress = nullptr
                                   );
 
-    /** Create a empty layer and add fields to it */
+    /** Constructor for QgsVectorLayerImport.
+     * @param uri URI for destination data source
+     * @param provider string key for destination data provider
+     * @param fields fields to include in created layer
+     * @param geometryType destination geometry type
+     * @param crs desired CRS, or an invalid (default constructed) CRS if
+     * not available
+     * @param overwrite set to true to overwrite any existing data source
+     * @param options optional provider dataset options
+     * @param progress optional progress dialog to show progress of export
+     */
     QgsVectorLayerImport( const QString &uri,
                           const QString &provider,
                           const QgsFields &fields,
                           QGis::WkbType geometryType,
-                          const QgsCoordinateReferenceSystem* crs,
+                          const QgsCoordinateReferenceSystem& crs,
                           bool overwrite = false,
-                          const QMap<QString, QVariant> *options = 0,
-                          QProgressDialog *progress = 0
+                          const QMap<QString, QVariant> *options = nullptr,
+                          QProgressDialog *progress = nullptr
                         );
 
     /** Checks whether there were any errors */
diff --git a/src/core/qgsvectorlayerimport.cpp b/src/core/qgsvectorlayerimport.cpp
index 2e0745b74e4..c034fbbd9f3 100644
--- a/src/core/qgsvectorlayerimport.cpp
+++ b/src/core/qgsvectorlayerimport.cpp
@@ -34,7 +34,7 @@ typedef QgsVectorLayerImport::ImportError createEmptyLayer_t(
   const QString &uri,
   const QgsFields &fields,
   QGis::WkbType geometryType,
-  const QgsCoordinateReferenceSystem *destCRS,
+  const QgsCoordinateReferenceSystem &destCRS,
   bool overwrite,
   QMap<int, int> *oldToNewAttrIdx,
   QString *errorMessage,
@@ -46,7 +46,7 @@ QgsVectorLayerImport::QgsVectorLayerImport( const QString &uri,
     const QString &providerKey,
     const QgsFields& fields,
     QGis::WkbType geometryType,
-    const QgsCoordinateReferenceSystem* crs,
+    const QgsCoordinateReferenceSystem& crs,
     bool overwrite,
     const QMap<QString, QVariant> *options,
     QProgressDialog *progress )
@@ -206,21 +206,21 @@ QgsVectorLayerImport::ImportError
 QgsVectorLayerImport::importLayer( QgsVectorLayer* layer,
                                    const QString& uri,
                                    const QString& providerKey,
-                                   const QgsCoordinateReferenceSystem *destCRS,
+                                   const QgsCoordinateReferenceSystem& destCRS,
                                    bool onlySelected,
                                    QString *errorMessage,
                                    bool skipAttributeCreation,
                                    QMap<QString, QVariant> *options,
                                    QProgressDialog *progress )
 {
-  const QgsCoordinateReferenceSystem* outputCRS;
+  QgsCoordinateReferenceSystem outputCRS;
   QgsCoordinateTransform* ct = nullptr;
   bool shallTransform = false;
 
   if ( !layer )
     return ErrInvalidLayer;
 
-  if ( destCRS && destCRS->isValid() )
+  if ( destCRS.isValid() )
   {
     // This means we should transform
     outputCRS = destCRS;
@@ -229,7 +229,7 @@ QgsVectorLayerImport::importLayer( QgsVectorLayer* layer,
   else
   {
     // This means we shouldn't transform, use source CRS as output (if defined)
-    outputCRS = &layer->crs();
+    outputCRS = layer->crs();
   }
 
 
@@ -314,8 +314,8 @@ QgsVectorLayerImport::importLayer( QgsVectorLayer* layer,
   const QgsFeatureIds& ids = layer->selectedFeaturesIds();
 
   // Create our transform
-  if ( destCRS )
-    ct = new QgsCoordinateTransform( layer->crs(), *destCRS );
+  if ( destCRS.isValid() )
+    ct = new QgsCoordinateTransform( layer->crs(), destCRS );
 
   // Check for failure
   if ( !ct )
diff --git a/src/core/qgsvectorlayerimport.h b/src/core/qgsvectorlayerimport.h
index 88f73dd0724..f4b4212f611 100644
--- a/src/core/qgsvectorlayerimport.h
+++ b/src/core/qgsvectorlayerimport.h
@@ -51,11 +51,24 @@ class CORE_EXPORT QgsVectorLayerImport
       ErrUserCancelled, /*!< User cancelled the import*/
     };
 
-    /** Write contents of vector layer to a different datasource */
+    /**
+     * Writes the contents of vector layer to a different datasource.
+     * @param layer source layer
+     * @param uri URI for destination data source
+     * @param providerKey string key for destination data provider
+     * @param destCRS destination CRS, or an invalid (default constructed) CRS if
+     * not available
+     * @param onlySelected set to true to export only selected features
+     * @param errorMessage if non-null, will be set to any error messages
+     * @param skipAttributeCreation set to true to skip exporting feature attributes
+     * @param options optional provider dataset options
+     * @param progress optional progress dialog to show progress of export
+     * @returns NoError for a successful export, or encountered error
+     */
     static ImportError importLayer( QgsVectorLayer* layer,
                                     const QString& uri,
                                     const QString& providerKey,
-                                    const QgsCoordinateReferenceSystem *destCRS,
+                                    const QgsCoordinateReferenceSystem& destCRS,
                                     bool onlySelected = false,
                                     QString *errorMessage = nullptr,
                                     bool skipAttributeCreation = false,
@@ -63,12 +76,22 @@ class CORE_EXPORT QgsVectorLayerImport
                                     QProgressDialog *progress = nullptr
                                   );
 
-    /** Create a empty layer and add fields to it */
+    /** Constructor for QgsVectorLayerImport.
+     * @param uri URI for destination data source
+     * @param provider string key for destination data provider
+     * @param fields fields to include in created layer
+     * @param geometryType destination geometry type
+     * @param crs desired CRS, or an invalid (default constructed) CRS if
+     * not available
+     * @param overwrite set to true to overwrite any existing data source
+     * @param options optional provider dataset options
+     * @param progress optional progress dialog to show progress of export
+     */
     QgsVectorLayerImport( const QString &uri,
                           const QString &provider,
                           const QgsFields &fields,
                           QGis::WkbType geometryType,
-                          const QgsCoordinateReferenceSystem* crs,
+                          const QgsCoordinateReferenceSystem& crs,
                           bool overwrite = false,
                           const QMap<QString, QVariant> *options = nullptr,
                           QProgressDialog *progress = nullptr
diff --git a/src/gui/qgsnewvectorlayerdialog.cpp b/src/gui/qgsnewvectorlayerdialog.cpp
index 4230f43b190..0e87a7d4927 100644
--- a/src/gui/qgsnewvectorlayerdialog.cpp
+++ b/src/gui/qgsnewvectorlayerdialog.cpp
@@ -270,14 +270,14 @@ QString QgsNewVectorLayerDialog::runAndCreateLayer( QWidget* parent, QString* pE
     QgsDebugMsg( "ogr provider loaded" );
 
     typedef bool ( *createEmptyDataSourceProc )( const QString&, const QString&, const QString&, QGis::WkbType,
-        const QList< QPair<QString, QString> >&, const QgsCoordinateReferenceSystem * );
+        const QList< QPair<QString, QString> >&, const QgsCoordinateReferenceSystem & );
     createEmptyDataSourceProc createEmptyDataSource = ( createEmptyDataSourceProc ) cast_to_fptr( myLib->resolve( "createEmptyDataSource" ) );
     if ( createEmptyDataSource )
     {
       if ( geometrytype != QGis::WKBUnknown )
       {
         QgsCoordinateReferenceSystem srs = QgsCRSCache::instance()->crsBySrsId( crsId );
-        if ( !createEmptyDataSource( fileName, fileformat, enc, geometrytype, attributes, &srs ) )
+        if ( !createEmptyDataSource( fileName, fileformat, enc, geometrytype, attributes, srs ) )
         {
           return QString::null;
         }
diff --git a/src/plugins/geometry_checker/ui/qgsgeometrycheckerresulttab.cpp b/src/plugins/geometry_checker/ui/qgsgeometrycheckerresulttab.cpp
index 7d3015012da..e0e107eebac 100644
--- a/src/plugins/geometry_checker/ui/qgsgeometrycheckerresulttab.cpp
+++ b/src/plugins/geometry_checker/ui/qgsgeometrycheckerresulttab.cpp
@@ -245,13 +245,13 @@ bool QgsGeometryCheckerResultTab::exportErrorsDo( const QString& file )
   {
     return false;
   }
-  typedef bool ( *createEmptyDataSourceProc )( const QString&, const QString&, const QString&, QGis::WkbType, const QList< QPair<QString, QString> >&, const QgsCoordinateReferenceSystem * );
+  typedef bool ( *createEmptyDataSourceProc )( const QString&, const QString&, const QString&, QGis::WkbType, const QList< QPair<QString, QString> >&, const QgsCoordinateReferenceSystem& );
   createEmptyDataSourceProc createEmptyDataSource = ( createEmptyDataSourceProc ) cast_to_fptr( ogrLib.resolve( "createEmptyDataSource" ) );
   if ( !createEmptyDataSource )
   {
     return false;
   }
-  if ( !createEmptyDataSource( file, "ESRI Shapefile", mFeaturePool->getLayer()->dataProvider()->encoding(), QGis::WKBPoint, attributes, &mFeaturePool->getLayer()->crs() ) )
+  if ( !createEmptyDataSource( file, "ESRI Shapefile", mFeaturePool->getLayer()->dataProvider()->encoding(), QGis::WKBPoint, attributes, mFeaturePool->getLayer()->crs() ) )
   {
     return false;
   }
diff --git a/src/providers/db2/qgsdb2dataitems.cpp b/src/providers/db2/qgsdb2dataitems.cpp
index 19ebf941240..00ad723fc2e 100644
--- a/src/providers/db2/qgsdb2dataitems.cpp
+++ b/src/providers/db2/qgsdb2dataitems.cpp
@@ -361,7 +361,7 @@ bool QgsDb2ConnectionItem::handleDrop( const QMimeData* data, const QString& toS
 
       QgsVectorLayerImport::ImportError err;
       QString importError;
-      err = QgsVectorLayerImport::importLayer( srcLayer, uri, "DB2", &srcLayer->crs(), false, &importError, false, nullptr, progress );
+      err = QgsVectorLayerImport::importLayer( srcLayer, uri, "DB2", srcLayer->crs(), false, &importError, false, nullptr, progress );
       if ( err == QgsVectorLayerImport::NoError )
       {
         importResults.append( tr( "%1: OK!" ).arg( u.name ) );
diff --git a/src/providers/db2/qgsdb2provider.cpp b/src/providers/db2/qgsdb2provider.cpp
index 1182babfec3..a2a133c7549 100644
--- a/src/providers/db2/qgsdb2provider.cpp
+++ b/src/providers/db2/qgsdb2provider.cpp
@@ -1263,15 +1263,14 @@ bool QgsDb2Provider::changeGeometryValues( const QgsGeometryMap &geometry_map )
   return true;
 }
 
-QgsVectorLayerImport::ImportError QgsDb2Provider::createEmptyLayer(
-  const QString& uri,
-  const QgsFields &fields,
-  QGis::WkbType wkbType,
-  const QgsCoordinateReferenceSystem *srs,
-  bool overwrite,
-  QMap<int, int> *oldToNewAttrIdxMap,
-  QString *errorMessage,
-  const QMap<QString, QVariant> *options )
+QgsVectorLayerImport::ImportError QgsDb2Provider::createEmptyLayer( const QString& uri,
+    const QgsFields &fields,
+    QGis::WkbType wkbType,
+    const QgsCoordinateReferenceSystem& srs,
+    bool overwrite,
+    QMap<int, int> *oldToNewAttrIdxMap,
+    QString *errorMessage,
+    const QMap<QString, QVariant> *options )
 {
   Q_UNUSED( options );
 
@@ -1297,8 +1296,8 @@ QgsVectorLayerImport::ImportError QgsDb2Provider::createEmptyLayer(
   // srs->posgisSrid() seems to return the authority id which is
   // most often the EPSG id.  Hopefully DB2 has defined an SRS using this
   // value as the srid / srs_id.  If not, we are out of luck.
-  QgsDebugMsg( "srs: " + srs->toWkt() );
-  long srid = srs->postgisSrid();
+  QgsDebugMsg( "srs: " + srs.toWkt() );
+  long srid = srs.postgisSrid();
   QgsDebugMsg( QString( "srid: %1" ).arg( srid ) );
   if ( srid >= 0 )
   {
@@ -1740,7 +1739,7 @@ QGISEXTERN QgsVectorLayerImport::ImportError createEmptyLayer(
   const QString& uri,
   const QgsFields &fields,
   QGis::WkbType wkbType,
-  const QgsCoordinateReferenceSystem *srs,
+  const QgsCoordinateReferenceSystem &srs,
   bool overwrite,
   QMap<int, int> *oldToNewAttrIdxMap,
   QString *errorMessage,
diff --git a/src/providers/db2/qgsdb2provider.h b/src/providers/db2/qgsdb2provider.h
index a125fb1d4c1..0368c9357dd 100644
--- a/src/providers/db2/qgsdb2provider.h
+++ b/src/providers/db2/qgsdb2provider.h
@@ -124,7 +124,7 @@ class QgsDb2Provider : public QgsVectorDataProvider
       const QString& uri,
       const QgsFields &fields,
       QGis::WkbType wkbType,
-      const QgsCoordinateReferenceSystem *srs,
+      const QgsCoordinateReferenceSystem& srs,
       bool overwrite,
       QMap<int, int> *oldToNewAttrIdxMap,
       QString *errorMessage = nullptr,
diff --git a/src/providers/mssql/qgsmssqldataitems.cpp b/src/providers/mssql/qgsmssqldataitems.cpp
index 256b57825d0..bd6f0a9da28 100644
--- a/src/providers/mssql/qgsmssqldataitems.cpp
+++ b/src/providers/mssql/qgsmssqldataitems.cpp
@@ -426,7 +426,7 @@ bool QgsMssqlConnectionItem::handleDrop( const QMimeData* data, const QString& t
 
       QgsVectorLayerImport::ImportError err;
       QString importError;
-      err = QgsVectorLayerImport::importLayer( srcLayer, uri, "mssql", &srcLayer->crs(), false, &importError, false, nullptr, progress );
+      err = QgsVectorLayerImport::importLayer( srcLayer, uri, "mssql", srcLayer->crs(), false, &importError, false, nullptr, progress );
       if ( err == QgsVectorLayerImport::NoError )
         importResults.append( tr( "%1: OK!" ).arg( u.name ) );
       else if ( err == QgsVectorLayerImport::ErrUserCancelled )
diff --git a/src/providers/mssql/qgsmssqlprovider.cpp b/src/providers/mssql/qgsmssqlprovider.cpp
index c4adb30e271..2a42b37a687 100644
--- a/src/providers/mssql/qgsmssqlprovider.cpp
+++ b/src/providers/mssql/qgsmssqlprovider.cpp
@@ -1650,15 +1650,14 @@ QGis::WkbType QgsMssqlProvider::getWkbType( const QString& geometryType, int dim
 }
 
 
-QgsVectorLayerImport::ImportError QgsMssqlProvider::createEmptyLayer(
-  const QString& uri,
-  const QgsFields &fields,
-  QGis::WkbType wkbType,
-  const QgsCoordinateReferenceSystem *srs,
-  bool overwrite,
-  QMap<int, int> *oldToNewAttrIdxMap,
-  QString *errorMessage,
-  const QMap<QString, QVariant> *options )
+QgsVectorLayerImport::ImportError QgsMssqlProvider::createEmptyLayer( const QString& uri,
+    const QgsFields &fields,
+    QGis::WkbType wkbType,
+    const QgsCoordinateReferenceSystem& srs,
+    bool overwrite,
+    QMap<int, int> *oldToNewAttrIdxMap,
+    QString *errorMessage,
+    const QMap<QString, QVariant> *options )
 {
   Q_UNUSED( options );
 
@@ -1758,23 +1757,23 @@ QgsVectorLayerImport::ImportError QgsMssqlProvider::createEmptyLayer(
 
   // set up spatial reference id
   int srid = 0;
-  if ( srs->isValid() )
+  if ( srs.isValid() )
   {
-    srid = srs->srsid();
+    srid = srs.srsid();
     QString auth_srid = "null";
     QString auth_name = "null";
-    QStringList sl = srs->authid().split( ':' );
+    QStringList sl = srs.authid().split( ':' );
     if ( sl.length() == 2 )
     {
       auth_name = '\'' + sl[0] + '\'';
       auth_srid = sl[1];
     }
     sql = QString( "IF NOT EXISTS (SELECT * FROM spatial_ref_sys WHERE srid=%1) INSERT INTO spatial_ref_sys (srid, auth_name, auth_srid, srtext, proj4text) VALUES (%1, %2, %3, '%4', '%5')" )
-          .arg( srs->srsid() )
+          .arg( srs.srsid() )
           .arg( auth_name,
                 auth_srid,
-                srs->toWkt(),
-                srs->toProj4() );
+                srs.toWkt(),
+                srs.toProj4() );
     if ( !q.exec( sql ) )
     {
       if ( errorMessage )
@@ -1958,7 +1957,7 @@ QGISEXTERN QgsVectorLayerImport::ImportError createEmptyLayer(
   const QString& uri,
   const QgsFields &fields,
   QGis::WkbType wkbType,
-  const QgsCoordinateReferenceSystem *srs,
+  const QgsCoordinateReferenceSystem &srs,
   bool overwrite,
   QMap<int, int> *oldToNewAttrIdxMap,
   QString *errorMessage,
diff --git a/src/providers/mssql/qgsmssqlprovider.h b/src/providers/mssql/qgsmssqlprovider.h
index 533d3115d45..66841f04ed3 100644
--- a/src/providers/mssql/qgsmssqlprovider.h
+++ b/src/providers/mssql/qgsmssqlprovider.h
@@ -192,7 +192,7 @@ class QgsMssqlProvider : public QgsVectorDataProvider
       const QString& uri,
       const QgsFields &fields,
       QGis::WkbType wkbType,
-      const QgsCoordinateReferenceSystem *srs,
+      const QgsCoordinateReferenceSystem &srs,
       bool overwrite,
       QMap<int, int> *oldToNewAttrIdxMap,
       QString *errorMessage = nullptr,
diff --git a/src/providers/ogr/qgsogrprovider.cpp b/src/providers/ogr/qgsogrprovider.cpp
index 903cf7a6439..62c667d296e 100644
--- a/src/providers/ogr/qgsogrprovider.cpp
+++ b/src/providers/ogr/qgsogrprovider.cpp
@@ -196,15 +196,14 @@ void QgsOgrProvider::repack()
 }
 
 
-QgsVectorLayerImport::ImportError QgsOgrProvider::createEmptyLayer(
-  const QString& uri,
-  const QgsFields &fields,
-  QGis::WkbType wkbType,
-  const QgsCoordinateReferenceSystem *srs,
-  bool overwrite,
-  QMap<int, int> *oldToNewAttrIdxMap,
-  QString *errorMessage,
-  const QMap<QString, QVariant> *options )
+QgsVectorLayerImport::ImportError QgsOgrProvider::createEmptyLayer( const QString& uri,
+    const QgsFields &fields,
+    QGis::WkbType wkbType,
+    const QgsCoordinateReferenceSystem& srs,
+    bool overwrite,
+    QMap<int, int> *oldToNewAttrIdxMap,
+    QString *errorMessage,
+    const QMap<QString, QVariant> *options )
 {
   QString encoding;
   QString driverName = "ESRI Shapefile";
@@ -2438,7 +2437,7 @@ QGISEXTERN bool createEmptyDataSource( const QString &uri,
                                        const QString &encoding,
                                        QGis::WkbType vectortype,
                                        const QList< QPair<QString, QString> > &attributes,
-                                       const QgsCoordinateReferenceSystem *srs = nullptr )
+                                       const QgsCoordinateReferenceSystem& srs = QgsCoordinateReferenceSystem() )
 {
   QgsDebugMsg( QString( "Creating empty vector layer with format: %1" ).arg( format ) );
 
@@ -2493,9 +2492,9 @@ QGISEXTERN bool createEmptyDataSource( const QString &uri,
   OGRSpatialReferenceH reference = nullptr;
 
   QgsCoordinateReferenceSystem mySpatialRefSys;
-  if ( srs )
+  if ( srs.isValid() )
   {
-    mySpatialRefSys = *srs;
+    mySpatialRefSys = srs;
   }
   else
   {
@@ -3335,7 +3334,7 @@ QGISEXTERN QgsVectorLayerImport::ImportError createEmptyLayer(
   const QString& uri,
   const QgsFields &fields,
   QGis::WkbType wkbType,
-  const QgsCoordinateReferenceSystem *srs,
+  const QgsCoordinateReferenceSystem &srs,
   bool overwrite,
   QMap<int, int> *oldToNewAttrIdxMap,
   QString *errorMessage,
diff --git a/src/providers/ogr/qgsogrprovider.h b/src/providers/ogr/qgsogrprovider.h
index 44b4ad1689c..36db66915fa 100644
--- a/src/providers/ogr/qgsogrprovider.h
+++ b/src/providers/ogr/qgsogrprovider.h
@@ -54,7 +54,7 @@ class QgsOgrProvider : public QgsVectorDataProvider
       const QString& uri,
       const QgsFields &fields,
       QGis::WkbType wkbType,
-      const QgsCoordinateReferenceSystem *srs,
+      const QgsCoordinateReferenceSystem &srs,
       bool overwrite,
       QMap<int, int> *oldToNewAttrIdxMap,
       QString *errorMessage = nullptr,
diff --git a/src/providers/postgres/qgspostgresdataitems.cpp b/src/providers/postgres/qgspostgresdataitems.cpp
index 36813d4f7a3..fa78f361a4a 100644
--- a/src/providers/postgres/qgspostgresdataitems.cpp
+++ b/src/providers/postgres/qgspostgresdataitems.cpp
@@ -233,7 +233,7 @@ bool QgsPGConnectionItem::handleDrop( const QMimeData * data, QString toSchema )
 
       QgsVectorLayerImport::ImportError err;
       QString importError;
-      err = QgsVectorLayerImport::importLayer( srcLayer, uri.uri( false ), "postgres", &srcLayer->crs(), false, &importError, false, nullptr, progress );
+      err = QgsVectorLayerImport::importLayer( srcLayer, uri.uri( false ), "postgres", srcLayer->crs(), false, &importError, false, nullptr, progress );
       if ( err == QgsVectorLayerImport::NoError )
         importResults.append( tr( "%1: OK!" ).arg( u.name ) );
       else if ( err == QgsVectorLayerImport::ErrUserCancelled )
diff --git a/src/providers/postgres/qgspostgresprovider.cpp b/src/providers/postgres/qgspostgresprovider.cpp
index 0f7be8c9668..c4b0396a047 100644
--- a/src/providers/postgres/qgspostgresprovider.cpp
+++ b/src/providers/postgres/qgspostgresprovider.cpp
@@ -3462,15 +3462,14 @@ bool QgsPostgresProvider::convertField( QgsField &field, const QMap<QString, QVa
   return true;
 }
 
-QgsVectorLayerImport::ImportError QgsPostgresProvider::createEmptyLayer(
-  const QString& uri,
-  const QgsFields &fields,
-  QGis::WkbType wkbType,
-  const QgsCoordinateReferenceSystem *srs,
-  bool overwrite,
-  QMap<int, int> *oldToNewAttrIdxMap,
-  QString *errorMessage,
-  const QMap<QString, QVariant> *options )
+QgsVectorLayerImport::ImportError QgsPostgresProvider::createEmptyLayer( const QString& uri,
+    const QgsFields &fields,
+    QGis::WkbType wkbType,
+    const QgsCoordinateReferenceSystem& srs,
+    bool overwrite,
+    QMap<int, int> *oldToNewAttrIdxMap,
+    QString *errorMessage,
+    const QMap<QString, QVariant> *options )
 {
   // populate members from the uri structure
   QgsDataSourceURI dsUri( uri );
@@ -3615,7 +3614,7 @@ QgsVectorLayerImport::ImportError QgsPostgresProvider::createEmptyLayer(
 
     // get geometry type, dim and srid
     int dim = 2;
-    long srid = srs->postgisSrid();
+    long srid = srs.postgisSrid();
 
     QgsPostgresConn::postgisWkbType( wkbType, geometryType, dim );
 
@@ -3854,7 +3853,7 @@ QGISEXTERN QgsVectorLayerImport::ImportError createEmptyLayer(
   const QString& uri,
   const QgsFields &fields,
   QGis::WkbType wkbType,
-  const QgsCoordinateReferenceSystem *srs,
+  const QgsCoordinateReferenceSystem& srs,
   bool overwrite,
   QMap<int, int> *oldToNewAttrIdxMap,
   QString *errorMessage,
diff --git a/src/providers/postgres/qgspostgresprovider.h b/src/providers/postgres/qgspostgresprovider.h
index 3b640198769..5dc6352cd01 100644
--- a/src/providers/postgres/qgspostgresprovider.h
+++ b/src/providers/postgres/qgspostgresprovider.h
@@ -58,7 +58,7 @@ class QgsPostgresProvider : public QgsVectorDataProvider
       const QString& uri,
       const QgsFields &fields,
       QGis::WkbType wkbType,
-      const QgsCoordinateReferenceSystem *srs,
+      const QgsCoordinateReferenceSystem &srs,
       bool overwrite,
       QMap<int, int> *oldToNewAttrIdxMap,
       QString *errorMessage = nullptr,
diff --git a/src/providers/spatialite/qgsspatialitedataitems.cpp b/src/providers/spatialite/qgsspatialitedataitems.cpp
index 74a09c98f02..8cd1547e8cb 100644
--- a/src/providers/spatialite/qgsspatialitedataitems.cpp
+++ b/src/providers/spatialite/qgsspatialitedataitems.cpp
@@ -232,7 +232,7 @@ bool QgsSLConnectionItem::handleDrop( const QMimeData * data, Qt::DropAction )
       QgsDebugMsg( "URI " + destUri.uri() );
       QgsVectorLayerImport::ImportError err;
       QString importError;
-      err = QgsVectorLayerImport::importLayer( srcLayer, destUri.uri(), "spatialite", &srcLayer->crs(), false, &importError, false, nullptr, progress );
+      err = QgsVectorLayerImport::importLayer( srcLayer, destUri.uri(), "spatialite", srcLayer->crs(), false, &importError, false, nullptr, progress );
       if ( err == QgsVectorLayerImport::NoError )
         importResults.append( tr( "%1: OK!" ).arg( u.name ) );
       else if ( err == QgsVectorLayerImport::ErrUserCancelled )
diff --git a/src/providers/spatialite/qgsspatialiteprovider.cpp b/src/providers/spatialite/qgsspatialiteprovider.cpp
index b4fc2980adc..9251553e7ae 100644
--- a/src/providers/spatialite/qgsspatialiteprovider.cpp
+++ b/src/providers/spatialite/qgsspatialiteprovider.cpp
@@ -93,15 +93,14 @@ bool QgsSpatiaLiteProvider::convertField( QgsField &field )
 
 
 QgsVectorLayerImport::ImportError
-QgsSpatiaLiteProvider::createEmptyLayer(
-  const QString& uri,
-  const QgsFields &fields,
-  QGis::WkbType wkbType,
-  const QgsCoordinateReferenceSystem *srs,
-  bool overwrite,
-  QMap<int, int> *oldToNewAttrIdxMap,
-  QString *errorMessage,
-  const QMap<QString, QVariant> *options )
+QgsSpatiaLiteProvider::createEmptyLayer( const QString& uri,
+    const QgsFields &fields,
+    QGis::WkbType wkbType,
+    const QgsCoordinateReferenceSystem& srs,
+    bool overwrite,
+    QMap<int, int> *oldToNewAttrIdxMap,
+    QString *errorMessage,
+    const QMap<QString, QVariant> *options )
 {
   Q_UNUSED( options );
 
@@ -224,7 +223,7 @@ QgsSpatiaLiteProvider::createEmptyLayer(
 
       // get geometry type, dim and srid
       int dim = 2;
-      long srid = srs->postgisSrid();
+      long srid = srs.postgisSrid();
 
       switch ( wkbType )
       {
@@ -5075,7 +5074,7 @@ QGISEXTERN QgsVectorLayerImport::ImportError createEmptyLayer(
   const QString& uri,
   const QgsFields &fields,
   QGis::WkbType wkbType,
-  const QgsCoordinateReferenceSystem *srs,
+  const QgsCoordinateReferenceSystem& srs,
   bool overwrite,
   QMap<int, int> *oldToNewAttrIdxMap,
   QString *errorMessage,
diff --git a/src/providers/spatialite/qgsspatialiteprovider.h b/src/providers/spatialite/qgsspatialiteprovider.h
index 09c5ce4190d..ffa2bdc0be8 100644
--- a/src/providers/spatialite/qgsspatialiteprovider.h
+++ b/src/providers/spatialite/qgsspatialiteprovider.h
@@ -59,7 +59,7 @@ class QgsSpatiaLiteProvider: public QgsVectorDataProvider
       const QString& uri,
       const QgsFields &fields,
       QGis::WkbType wkbType,
-      const QgsCoordinateReferenceSystem *srs,
+      const QgsCoordinateReferenceSystem& srs,
       bool overwrite,
       QMap<int, int> *oldToNewAttrIdxMap,
       QString *errorMessage = nullptr,