QgsVectorLayer code cleaning use enums instead of int

It was one of the TODOs for QGIS 3

python/core/geometry/qgsgeometry.sip

@@ -52,8 +52,11 @@ class QgsGeometry
       Success,
       NothingHappened,
       InvalidBaseGeometry,
-      InvalidInput,
+      InvalidInputGeometryType,
+      SelectionIsEmpty,
+      SelectionIsGreaterThanOne,
       GeometryEngineError,
+      LayerNotEditable,
       AddPartSelectedGeometryNotFound,
       AddPartNotMultiGeometry,
       AddRingNotClosed,

python/core/qgsvectorlayer.sip

@@ -1043,32 +1043,50 @@ Return the provider type for this layer
  :rtype: bool
 %End
 
-    int addRing( const QVector<QgsPointXY> &ring, QgsFeatureId *featureId = 0 );
+    QgsGeometry::OperationResult addRing( const QVector<QgsPointXY> &ring, QgsFeatureId *featureId = 0 );
 %Docstring
- :rtype: int
+ Adds a ring to polygon/multipolygon features
+ \param ring ring to add
+ \param featureId if specified, feature ID for feature ring was added to will be stored in this parameter
+ :return: QgsGeometry.OperationResult
+ :rtype: QgsGeometry.OperationResult
 %End
 
-    int addRing( QgsCurve *ring /Transfer/, QgsFeatureId *featureId = 0 ) /PyName=addCurvedRing/;
+    QgsGeometry::OperationResult addRing( QgsCurve *ring /Transfer/, QgsFeatureId *featureId = 0 ) /PyName=addCurvedRing/;
 %Docstring
- :rtype: int
+ Adds a ring to polygon/multipolygon features (takes ownership)
+ \param ring ring to add
+ \param featureId if specified, feature ID for feature ring was added to will be stored in this parameter
+ :return: QgsGeometry.OperationResult
+.. note::
+
+   available in Python as addCurvedRing
+ :rtype: QgsGeometry.OperationResult
 %End
 
-    int addPart( const QList<QgsPointXY> &ring );
+    QgsGeometry::OperationResult addPart( const QList<QgsPointXY> &ring );
 %Docstring
- :rtype: int
+ Adds a new part polygon to a multipart feature
+ :return: QgsGeometry.OperationResult
+ :rtype: QgsGeometry.OperationResult
 %End
 
-    int addPart( const QgsPointSequence &ring ) /PyName=addPartV2/;
+    QgsGeometry::OperationResult addPart( const QgsPointSequence &ring ) /PyName=addPartV2/;
 %Docstring
- :rtype: int
+ Adds a new part polygon to a multipart feature
+ :return: QgsGeometry.OperationResult
+.. note::
+
+   available in Python bindings as addPartV2
+ :rtype: QgsGeometry.OperationResult
 %End
 
-    int addPart( QgsCurve *ring /Transfer/ ) /PyName=addCurvedPart/;
+    QgsGeometry::OperationResult addPart( QgsCurve *ring /Transfer/ ) /PyName=addCurvedPart/;
 %Docstring
 .. note::
 
    available in Python as addCurvedPart
- :rtype: int
+ :rtype: QgsGeometry.OperationResult
 %End
 
     int translateFeature( QgsFeatureId featureId, double dx, double dy );
@@ -1081,14 +1099,22 @@ Return the provider type for this layer
  :rtype: int
 %End
 
-    int splitParts( const QVector<QgsPointXY> &splitLine, bool topologicalEditing = false );
+    QgsGeometry::OperationResult splitParts( const QVector<QgsPointXY> &splitLine, bool topologicalEditing = false );
 %Docstring
- :rtype: int
+ Splits parts cut by the given line
+  \param splitLine line that splits the layer features
+  \param topologicalEditing true if topological editing is enabled
+  :return: QgsGeometry.OperationResult
+ :rtype: QgsGeometry.OperationResult
 %End
 
-    int splitFeatures( const QVector<QgsPointXY> &splitLine, bool topologicalEditing = false );
+    QgsGeometry::OperationResult splitFeatures( const QVector<QgsPointXY> &splitLine, bool topologicalEditing = false );
 %Docstring
- :rtype: int
+ Splits features cut by the given line
+  \param splitLine line that splits the layer features
+  \param topologicalEditing true if topological editing is enabled
+  :return: QgsGeometry.OperationResult
+ :rtype: QgsGeometry.OperationResult
 %End
 
     int addTopologicalPoints( const QgsGeometry &geom );

src/app/qgsmaptoolfillring.cpp

@@ -90,28 +90,30 @@ void QgsMapToolFillRing::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
 
     QVector< QgsPointXY > pointList = points();
 
-    int addRingReturnCode = vlayer->addRing( pointList, &fid );
+    QgsGeometry::OperationResult addRingReturnCode = vlayer->addRing( pointList, &fid );
-    if ( addRingReturnCode != 0 )
+
+    // AP: this is all dead code:
+    //todo: open message box to communicate errors
+    if ( addRingReturnCode != QgsGeometry::OperationResult::Success )
     {
       QString errorMessage;
-      //todo: open message box to communicate errors
+      if ( addRingReturnCode == QgsGeometry::OperationResult::InvalidInputGeometryType )
-      if ( addRingReturnCode == 1 )
       {
         errorMessage = tr( "a problem with geometry type occurred" );
       }
-      else if ( addRingReturnCode == 2 )
+      else if ( addRingReturnCode == QgsGeometry::OperationResult::AddRingNotClosed )
       {
         errorMessage = tr( "the inserted Ring is not closed" );
       }
-      else if ( addRingReturnCode == 3 )
+      else if ( addRingReturnCode ==  QgsGeometry::OperationResult::AddRingNotValid )
       {
         errorMessage = tr( "the inserted Ring is not a valid geometry" );
       }
-      else if ( addRingReturnCode == 4 )
+      else if ( addRingReturnCode == QgsGeometry::OperationResult::AddRingCrossesExistingRings )
       {
         errorMessage = tr( "the inserted Ring crosses existing rings" );
       }
-      else if ( addRingReturnCode == 5 )
+      else if ( addRingReturnCode == QgsGeometry::OperationResult::AddRingNotInExistingFeature )
       {
         errorMessage = tr( "the inserted Ring is not contained in a feature" );
       }

src/app/qgsmaptoolsplitfeatures.cpp

@@ -93,9 +93,9 @@ void QgsMapToolSplitFeatures::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
     //bring up dialog if a split was not possible (polygon) or only done once (line)
     int topologicalEditing = QgsProject::instance()->topologicalEditing();
     vlayer->beginEditCommand( tr( "Features split" ) );
-    int returnCode = vlayer->splitFeatures( points(), topologicalEditing );
+    QgsGeometry::OperationResult returnCode = vlayer->splitFeatures( points(), topologicalEditing );
     vlayer->endEditCommand();
-    if ( returnCode == 4 )
+    if ( returnCode == QgsGeometry::OperationResult::NothingHappened )
     {
       QgisApp::instance()->messageBar()->pushMessage(
         tr( "No features were split" ),
@@ -103,7 +103,7 @@ void QgsMapToolSplitFeatures::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
         QgsMessageBar::WARNING,
         QgisApp::instance()->messageTimeout() );
     }
-    else if ( returnCode == 3 )
+    else if ( returnCode == QgsGeometry::OperationResult::GeometryEngineError )
     {
       QgisApp::instance()->messageBar()->pushMessage(
         tr( "No feature split done" ),
@@ -111,7 +111,7 @@ void QgsMapToolSplitFeatures::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
         QgsMessageBar::WARNING,
         QgisApp::instance()->messageTimeout() );
     }
-    else if ( returnCode == 7 )
+    else if ( returnCode == QgsGeometry::OperationResult::InvalidBaseGeometry )
     {
       QgisApp::instance()->messageBar()->pushMessage(
         tr( "No feature split done" ),
@@ -119,7 +119,7 @@ void QgsMapToolSplitFeatures::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
         QgsMessageBar::WARNING,
         QgisApp::instance()->messageTimeout() );
     }
-    else if ( returnCode != 0 )
+    else if ( returnCode != QgsGeometry::OperationResult::Success )
     {
       //several intersections but only one split (most likely line)
       QgisApp::instance()->messageBar()->pushMessage(

src/app/qgsmaptoolsplitparts.cpp

@@ -91,9 +91,9 @@ void QgsMapToolSplitParts::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
     //bring up dialog if a split was not possible (polygon) or only done once (line)
     bool topologicalEditing = QgsProject::instance()->topologicalEditing();
     vlayer->beginEditCommand( tr( "Parts split" ) );
-    int returnCode = vlayer->splitParts( points(), topologicalEditing );
+    QgsGeometry::OperationResult returnCode = vlayer->splitParts( points(), topologicalEditing );
     vlayer->endEditCommand();
-    if ( returnCode == 4 )
+    if ( returnCode == QgsGeometry::OperationResult::NothingHappened )
     {
       QgisApp::instance()->messageBar()->pushMessage(
         tr( "No parts were split" ),
@@ -101,7 +101,7 @@ void QgsMapToolSplitParts::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
         QgsMessageBar::WARNING,
         QgisApp::instance()->messageTimeout() );
     }
-    else if ( returnCode == 3 )
+    else if ( returnCode == QgsGeometry::OperationResult::GeometryEngineError )
     {
       QgisApp::instance()->messageBar()->pushMessage(
         tr( "No part split done" ),
@@ -109,7 +109,7 @@ void QgsMapToolSplitParts::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
         QgsMessageBar::WARNING,
         QgisApp::instance()->messageTimeout() );
     }
-    else if ( returnCode == 7 )
+    else if ( returnCode == QgsGeometry::OperationResult::InvalidBaseGeometry )
     {
       QgisApp::instance()->messageBar()->pushMessage(
         tr( "No part split done" ),
@@ -117,7 +117,7 @@ void QgsMapToolSplitParts::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
         QgsMessageBar::WARNING,
         QgisApp::instance()->messageTimeout() );
     }
-    else if ( returnCode != 0 )
+    else if ( returnCode != QgsGeometry::OperationResult::Success )
     {
       //several intersections but only one split (most likely line)
       QgisApp::instance()->messageBar()->pushMessage(

src/core/geometry/qgsgeometry.cpp

@@ -625,7 +625,7 @@ QgsGeometry::OperationResult QgsGeometry::addRing( QgsCurve *ring )
   std::unique_ptr< QgsCurve > r( ring );
   if ( !d->geometry )
   {
-    return InvalidInput;
+    return InvalidInputGeometryType;
   }
 
   detach();
@@ -816,7 +816,7 @@ QgsGeometry::OperationResult QgsGeometry::splitGeometry( const QVector<QgsPointX
     case QgsGeometryEngine::InvalidBaseGeometry:
       return QgsGeometry::InvalidBaseGeometry;
     case QgsGeometryEngine::InvalidInput:
-      return QgsGeometry::InvalidInput;
+      return QgsGeometry::InvalidInputGeometryType;
     case QgsGeometryEngine::SplitCannotSplitPoint:
       return QgsGeometry::SplitCannotSplitPoint;
     case QgsGeometryEngine::NothingHappened:
@@ -857,7 +857,7 @@ QgsGeometry::OperationResult QgsGeometry::reshapeGeometry( const QgsLineString &
     case QgsGeometryEngine::InvalidBaseGeometry:
       return InvalidBaseGeometry;
     case QgsGeometryEngine::InvalidInput:
-      return InvalidInput;
+      return InvalidInputGeometryType;
     case QgsGeometryEngine::SplitCannotSplitPoint: // should not happen
       return GeometryEngineError;
     case QgsGeometryEngine::NothingHappened:

src/core/geometry/qgsgeometry.h

@@ -121,8 +121,11 @@ class CORE_EXPORT QgsGeometry
       Success = 0, //!< Operation succeeded
       NothingHappened = 1000, //!< Nothing happened, without any error
       InvalidBaseGeometry, //!< The base geometry on which the operation is done is invalid or empty
-      InvalidInput, //!< The input geometry (ring, part, split line, etc.) has not the correct geometry type
+      InvalidInputGeometryType, //!< The input geometry (ring, part, split line, etc.) has not the correct geometry type
+      SelectionIsEmpty, //!< No features were selected
+      SelectionIsGreaterThanOne, //!< More than one features were selected
       GeometryEngineError, //!< Geometry engine misses a method implemented or an error occurred in the geometry engine
+      LayerNotEditable, //!< Cannot edit layer
       /* Add part issues */
       AddPartSelectedGeometryNotFound, //!< The selected geometry cannot be found
       AddPartNotMultiGeometry, //!< The source geometry is not multi

src/core/geometry/qgsgeometryeditutils.cpp

@@ -30,7 +30,7 @@ QgsGeometry::OperationResult QgsGeometryEditUtils::addRing( QgsAbstractGeometry
 {
   if ( !ring )
   {
-    return QgsGeometry::InvalidInput;
+    return QgsGeometry::InvalidInputGeometryType;
   }
 
   QVector< QgsCurvePolygon * > polygonList;
@@ -50,7 +50,7 @@ QgsGeometry::OperationResult QgsGeometryEditUtils::addRing( QgsAbstractGeometry
   }
   else
   {
-    return QgsGeometry::InvalidInput; //not polygon / multipolygon;
+    return QgsGeometry::InvalidInputGeometryType; //not polygon / multipolygon;
   }
 
   //ring must be closed
@@ -104,7 +104,7 @@ QgsGeometry::OperationResult QgsGeometryEditUtils::addPart( QgsAbstractGeometry
 
   if ( !part )
   {
-    return QgsGeometry::InvalidInput;
+    return QgsGeometry::InvalidInputGeometryType;
   }
 
   //multitype?
@@ -155,19 +155,19 @@ QgsGeometry::OperationResult QgsGeometryEditUtils::addPart( QgsAbstractGeometry
       {
         while ( geomCollection->numGeometries() > n )
           geomCollection->removeGeometry( n );
-        return QgsGeometry::InvalidInput;
+        return QgsGeometry::InvalidInputGeometryType;
       }
     }
     else
     {
-      return QgsGeometry::InvalidInput;
+      return QgsGeometry::InvalidInputGeometryType;
     }
   }
   else
   {
     added = geomCollection->addGeometry( part.release() );
   }
-  return added ? QgsGeometry::Success : QgsGeometry::InvalidInput;
+  return added ? QgsGeometry::Success : QgsGeometry::InvalidInputGeometryType;
 }
 
 bool QgsGeometryEditUtils::deleteRing( QgsAbstractGeometry *geom, int ringNum, int partNum )

src/core/qgsvectorlayer.cpp

@@ -491,7 +491,7 @@ void QgsVectorLayer::modifySelection( const QgsFeatureIds &selectIds, const QgsF
   QgsFeatureIds intersectingIds = selectIds & deselectIds;
   if ( !intersectingIds.isEmpty() )
   {
-    QgsDebugMsg( "Trying to select and deselect the same item at the same time. Unsure what to do. Selecting dubious items." );
+    QgsDebugMsgLevel( QStringLiteral( "Trying to select and deselect the same item at the same time. Unsure what to do. Selecting dubious items." ), 3 );
   }
 
   mSelectedFeatureIds -= deselectIds;
@@ -584,7 +584,7 @@ QgsWkbTypes::GeometryType QgsVectorLayer::geometryType() const
   }
   else
   {
-    QgsDebugMsg( "invalid layer or pointer to mDataProvider is null" );
+    QgsDebugMsgLevel( QStringLiteral( "invalid layer or pointer to mDataProvider is null" ), 3 );
   }
 
   // We shouldn't get here, and if we have, other things are likely to
@@ -592,7 +592,9 @@ QgsWkbTypes::GeometryType QgsVectorLayer::geometryType() const
   // rewritten to cope with a value of Qgis::Unknown. To make this
   // need known, the following message is printed every time we get
   // here.
-  QgsDebugMsg( "WARNING: This code should never be reached. Problems may occur..." );
+  // AP: it looks like we almost always get here, since 2.x ... either we remove this
+  //     warning of take care of the problems that may occur
+  QgsDebugMsg( QStringLiteral( "WARNING: This code should never be reached. Problems may occur..." ) );
 
   return QgsWkbTypes::UnknownGeometry;
 }
@@ -736,17 +738,17 @@ QgsVectorLayerFeatureCounter *QgsVectorLayer::countSymbolFeatures()
 
   if ( !mValid )
   {
-    QgsDebugMsg( "invoked with invalid layer" );
+    QgsDebugMsgLevel( QStringLiteral( "invoked with invalid layer" ), 3 );
     return mFeatureCounter;
   }
   if ( !mDataProvider )
   {
-    QgsDebugMsg( "invoked with null mDataProvider" );
+    QgsDebugMsgLevel( QStringLiteral( "invoked with null mDataProvider" ), 3 );
     return mFeatureCounter;
   }
   if ( !mRenderer )
   {
-    QgsDebugMsg( "invoked with null mRenderer" );
+    QgsDebugMsgLevel( QStringLiteral( "invoked with null mRenderer" ), 3 );
     return mFeatureCounter;
   }
 
@@ -816,7 +818,7 @@ QgsRectangle QgsVectorLayer::extent() const
     QgsRectangle mbr = mDataProvider->extent();
 
     // show the extent
-    QgsDebugMsg( "Extent of layer: " + mbr.toString() );
+    QgsDebugMsgLevel( QStringLiteral( "Extent of layer: %1" ).arg( mbr.toString() ), 3 );
     // store the extent
     mValidExtent = true;
     mExtent = mbr;
@@ -829,7 +831,7 @@ QgsRectangle QgsVectorLayer::extent() const
 
   if ( !mValid || !mDataProvider )
   {
-    QgsDebugMsg( "invoked with invalid layer or null mDataProvider" );
+    QgsDebugMsgLevel( QStringLiteral( "invoked with invalid layer or null mDataProvider" ), 3 );
     return rect;
   }
 
@@ -899,7 +901,7 @@ QString QgsVectorLayer::subsetString() const
 {
   if ( !mValid || !mDataProvider )
   {
-    QgsDebugMsg( "invoked with invalid layer or null mDataProvider" );
+    QgsDebugMsgLevel( QStringLiteral( "invoked with invalid layer or null mDataProvider" ), 3 );
     return QString();
   }
   return mDataProvider->subsetString();
@@ -909,7 +911,7 @@ bool QgsVectorLayer::setSubsetString( const QString &subset )
 {
   if ( !mValid || !mDataProvider )
   {
-    QgsDebugMsg( "invoked with invalid layer or null mDataProvider" );
+    QgsDebugMsgLevel( QStringLiteral( "invoked with invalid layer or null mDataProvider" ), 3 );
     return false;
   }
 
@@ -977,7 +979,7 @@ bool QgsVectorLayer::updateFeature( const QgsFeature &updatedFeature, bool skipD
   QgsFeature currentFeature = getFeature( updatedFeature.id() );
   if ( currentFeature.isValid() )
   {
-    QgsDebugMsg( QString( "feature %1 could not be retrieved" ).arg( updatedFeature.id() ) );
+    QgsDebugMsgLevel( QStringLiteral( "feature %1 could not be retrieved" ).arg( updatedFeature.id() ), 3 );
 
     if ( updatedFeature.hasGeometry() && currentFeature.hasGeometry() && !updatedFeature.geometry().isGeosEqual( currentFeature.geometry() ) )
     {
@@ -987,7 +989,7 @@ bool QgsVectorLayer::updateFeature( const QgsFeature &updatedFeature, bool skipD
       }
       else
       {
-        QgsDebugMsg( QString( "geometry of feature %1 could not be changed." ).arg( updatedFeature.id() ) );
+        QgsDebugMsgLevel( QStringLiteral( "geometry of feature %1 could not be changed." ).arg( updatedFeature.id() ), 3 );
       }
     }
 
@@ -1004,7 +1006,7 @@ bool QgsVectorLayer::updateFeature( const QgsFeature &updatedFeature, bool skipD
         }
         else
         {
-          QgsDebugMsg( QString( "attribute %1 of feature %2 could not be changed." ).arg( attr ).arg( updatedFeature.id() ) );
+          QgsDebugMsgLevel( QStringLiteral( "attribute %1 of feature %2 could not be changed." ).arg( attr ).arg( updatedFeature.id() ), 3 );
           hasError = true;
         }
       }
@@ -1116,13 +1118,13 @@ bool QgsVectorLayer::deleteSelectedFeatures( int *deletedCount )
   return deleted == count;
 }
 
-int QgsVectorLayer::addRing( const QVector<QgsPointXY> &ring, QgsFeatureId *featureId )
+QgsGeometry::OperationResult QgsVectorLayer::addRing( const QVector<QgsPointXY> &ring, QgsFeatureId *featureId )
 {
   if ( !mValid || !mEditBuffer || !mDataProvider )
-    return 6;
+    return QgsGeometry::OperationResult::LayerNotEditable;
 
   QgsVectorLayerEditUtils utils( this );
-  int result = 5;
+  QgsGeometry::OperationResult result = QgsGeometry::OperationResult::AddRingNotInExistingFeature;
 
   //first try with selected features
   if ( !mSelectedFeatureIds.isEmpty() )
@@ -1130,7 +1132,7 @@ int QgsVectorLayer::addRing( const QVector<QgsPointXY> &ring, QgsFeatureId *feat
     result = utils.addRing( ring, mSelectedFeatureIds, featureId );
   }
 
-  if ( result != 0 )
+  if ( result != QgsGeometry::OperationResult::Success )
   {
     //try with all intersecting features
     result = utils.addRing( ring, QgsFeatureIds(), featureId );
@@ -1139,27 +1141,27 @@ int QgsVectorLayer::addRing( const QVector<QgsPointXY> &ring, QgsFeatureId *feat
   return result;
 }
 
-int QgsVectorLayer::addRing( QgsCurve *ring, QgsFeatureId *featureId )
+QgsGeometry::OperationResult QgsVectorLayer::addRing( QgsCurve *ring, QgsFeatureId *featureId )
 {
   if ( !mValid || !mEditBuffer || !mDataProvider )
   {
     delete ring;
-    return 6;
+    return QgsGeometry::OperationResult::LayerNotEditable;
   }
 
   if ( !ring )
   {
-    return 1;
+    return QgsGeometry::OperationResult::InvalidInputGeometryType;
   }
 
   if ( !ring->isClosed() )
   {
     delete ring;
-    return 2;
+    return QgsGeometry::OperationResult::AddRingNotClosed;
   }
 
   QgsVectorLayerEditUtils utils( this );
-  int result = 5;
+  QgsGeometry::OperationResult result = QgsGeometry::OperationResult::AddRingNotInExistingFeature;
 
   //first try with selected features
   if ( !mSelectedFeatureIds.isEmpty() )
@@ -1167,7 +1169,7 @@ int QgsVectorLayer::addRing( QgsCurve *ring, QgsFeatureId *featureId )
     result = utils.addRing( static_cast< QgsCurve * >( ring->clone() ), mSelectedFeatureIds, featureId );
   }
 
-  if ( result != 0 )
+  if ( result != QgsGeometry::OperationResult::Success )
   {
     //try with all intersecting features
     result = utils.addRing( static_cast< QgsCurve * >( ring->clone() ), QgsFeatureIds(), featureId );
@@ -1177,80 +1179,80 @@ int QgsVectorLayer::addRing( QgsCurve *ring, QgsFeatureId *featureId )
   return result;
 }
 
-int QgsVectorLayer::addPart( const QList<QgsPointXY> &points )
+QgsGeometry::OperationResult QgsVectorLayer::addPart( const QList<QgsPointXY> &points )
 {
   if ( !mValid || !mEditBuffer || !mDataProvider )
-    return 7;
+    return QgsGeometry::OperationResult::LayerNotEditable;
 
   //number of selected features must be 1
 
   if ( mSelectedFeatureIds.empty() )
   {
-    QgsDebugMsg( "Number of selected features <1" );
+    QgsDebugMsgLevel( "Number of selected features < 1", 3 );
-    return 4;
+    return QgsGeometry::OperationResult::SelectionIsEmpty;
   }
   else if ( mSelectedFeatureIds.size() > 1 )
   {
-    QgsDebugMsg( "Number of selected features >1" );
+    QgsDebugMsgLevel( "Number of selected features > 1", 3 );
-    return 5;
+    return QgsGeometry::OperationResult::SelectionIsGreaterThanOne;
   }
 
   QgsVectorLayerEditUtils utils( this );
-  int result = utils.addPart( points, *mSelectedFeatureIds.constBegin() );
+  QgsGeometry::OperationResult result = utils.addPart( points, *mSelectedFeatureIds.constBegin() );
 
-  if ( result == 0 )
+  if ( result == QgsGeometry::OperationResult::Success )
     updateExtents();
   return result;
 }
 
-int QgsVectorLayer::addPart( const QgsPointSequence &points )
+QgsGeometry::OperationResult QgsVectorLayer::addPart( const QgsPointSequence &points )
 {
   if ( !mValid || !mEditBuffer || !mDataProvider )
-    return 7;
+    return QgsGeometry::OperationResult::LayerNotEditable;
 
   //number of selected features must be 1
 
   if ( mSelectedFeatureIds.empty() )
   {
-    QgsDebugMsg( "Number of selected features <1" );
+    QgsDebugMsgLevel( "Number of selected features <1", 3 );
-    return 4;
+    return QgsGeometry::OperationResult::SelectionIsEmpty;
   }
   else if ( mSelectedFeatureIds.size() > 1 )
   {
-    QgsDebugMsg( "Number of selected features >1" );
+    QgsDebugMsgLevel( "Number of selected features >1", 3 );
-    return 5;
+    return QgsGeometry::OperationResult::SelectionIsGreaterThanOne;
   }
 
   QgsVectorLayerEditUtils utils( this );
-  int result = utils.addPart( points, *mSelectedFeatureIds.constBegin() );
+  QgsGeometry::OperationResult result = utils.addPart( points, *mSelectedFeatureIds.constBegin() );
 
-  if ( result == 0 )
+  if ( result == QgsGeometry::OperationResult::Success )
     updateExtents();
   return result;
 }
 
-int QgsVectorLayer::addPart( QgsCurve *ring )
+QgsGeometry::OperationResult QgsVectorLayer::addPart( QgsCurve *ring )
 {
   if ( !mValid || !mEditBuffer || !mDataProvider )
-    return 7;
+    return QgsGeometry::OperationResult::LayerNotEditable;
 
   //number of selected features must be 1
 
   if ( mSelectedFeatureIds.empty() )
   {
-    QgsDebugMsg( "Number of selected features <1" );
+    QgsDebugMsgLevel( "Number of selected features <1", 3 );
-    return 4;
+    return QgsGeometry::OperationResult::SelectionIsEmpty;
   }
   else if ( mSelectedFeatureIds.size() > 1 )
   {
-    QgsDebugMsg( "Number of selected features >1" );
+    QgsDebugMsgLevel( "Number of selected features >1", 3 );
-    return 5;
+    return QgsGeometry::OperationResult::SelectionIsGreaterThanOne;
   }
 
   QgsVectorLayerEditUtils utils( this );
-  int result = utils.addPart( ring, *mSelectedFeatureIds.constBegin() );
+  QgsGeometry::OperationResult result = utils.addPart( ring, *mSelectedFeatureIds.constBegin() );
 
-  if ( result == 0 )
+  if ( result == QgsGeometry::OperationResult::Success )
     updateExtents();
   return result;
 }
@@ -1258,29 +1260,29 @@ int QgsVectorLayer::addPart( QgsCurve *ring )
 int QgsVectorLayer::translateFeature( QgsFeatureId featureId, double dx, double dy )
 {
   if ( !mValid || !mEditBuffer || !mDataProvider )
-    return -1;
+    return QgsGeometry::OperationResult::LayerNotEditable;
 
   QgsVectorLayerEditUtils utils( this );
   int result = utils.translateFeature( featureId, dx, dy );
 
-  if ( result == 0 )
+  if ( result == QgsGeometry::OperationResult::Success )
     updateExtents();
   return result;
 }
 
-int QgsVectorLayer::splitParts( const QVector<QgsPointXY> &splitLine, bool topologicalEditing )
+QgsGeometry::OperationResult QgsVectorLayer::splitParts( const QVector<QgsPointXY> &splitLine, bool topologicalEditing )
 {
   if ( !mValid || !mEditBuffer || !mDataProvider )
-    return -1;
+    return QgsGeometry::OperationResult::LayerNotEditable;
 
   QgsVectorLayerEditUtils utils( this );
   return utils.splitParts( splitLine, topologicalEditing );
 }
 
-int QgsVectorLayer::splitFeatures( const QVector<QgsPointXY> &splitLine, bool topologicalEditing )
+QgsGeometry::OperationResult QgsVectorLayer::splitFeatures( const QVector<QgsPointXY> &splitLine, bool topologicalEditing )
 {
   if ( !mValid || !mEditBuffer || !mDataProvider )
-    return -1;
+    return QgsGeometry::OperationResult::LayerNotEditable;
 
   QgsVectorLayerEditUtils utils( this );
   return utils.splitFeatures( splitLine, topologicalEditing );
@@ -1377,7 +1379,7 @@ bool QgsVectorLayer::startEditing()
 
 bool QgsVectorLayer::readXml( const QDomNode &layer_node, const QgsReadWriteContext &context )
 {
-  QgsDebugMsg( QString( "Datasource in QgsVectorLayer::readXml: " ) + mDataSource.toLocal8Bit().data() );
+  QgsDebugMsgLevel( QStringLiteral( "Datasource in QgsVectorLayer::readXml: %1" ).arg( mDataSource.toLocal8Bit().data() ), 3 );
 
   //process provider key
   QDomNode pkeyNode = layer_node.namedItem( QStringLiteral( "provider" ) );
@@ -1532,18 +1534,18 @@ bool QgsVectorLayer::setDataProvider( QString const &provider )
   mDataProvider = qobject_cast<QgsVectorDataProvider *>( QgsProviderRegistry::instance()->createProvider( provider, dataSource ) );
   if ( !mDataProvider )
   {
-    QgsDebugMsg( " unable to get data provider" );
+    QgsDebugMsgLevel( QStringLiteral( "Unable to get data provider" ), 2 );
     return false;
   }
 
   connect( mDataProvider, &QgsVectorDataProvider::raiseError, this, &QgsVectorLayer::raiseError );
 
-  QgsDebugMsgLevel( "Instantiated the data provider plugin", 4 );
+  QgsDebugMsgLevel( QStringLiteral( "Instantiated the data provider plugin" ), 2 );
 
   mValid = mDataProvider->isValid();
   if ( !mValid )
   {
-    QgsDebugMsg( "Invalid provider plugin " + QString( mDataSource.toUtf8() ) );
+    QgsDebugMsgLevel( QStringLiteral( "Invalid provider plugin %1" ).arg( QString( mDataSource.toUtf8() ) ), 2 );
     return false;
   }
 
@@ -1558,7 +1560,7 @@ bool QgsVectorLayer::setDataProvider( QString const &provider )
 
   if ( mProviderKey == QLatin1String( "postgres" ) )
   {
-    QgsDebugMsg( "Beautifying layer name " + name() );
+    QgsDebugMsgLevel( QStringLiteral( "Beautifying layer name %1" ).arg( name() ), 3 );
 
     // adjust the display name for postgres layers
     QRegExp reg( R"lit("[^"]+"\."([^"] + )"( \([^)]+\))?)lit" );
@@ -1582,7 +1584,7 @@ bool QgsVectorLayer::setDataProvider( QString const &provider )
         setName( lName );
     }
 
-    QgsDebugMsg( "Beautified layer name " + name() );
+    QgsDebugMsgLevel( QStringLiteral( "Beautified layer name %1" ).arg( name() ), 3 );
 
     // deal with unnecessary schema qualification to make v.in.ogr happy
     // and remove unnecessary key
@@ -1629,7 +1631,7 @@ bool QgsVectorLayer::writeXml( QDomNode &layer_node,
 
   if ( mapLayerNode.isNull() || ( "maplayer" != mapLayerNode.nodeName() ) )
   {
-    QgsDebugMsg( "can't find <maplayer>" );
+    QgsDebugMsgLevel( QStringLiteral( "can't find <maplayer>" ), 2 );
     return false;
   }
 
@@ -2520,7 +2522,7 @@ bool QgsVectorLayer::deleteFeatures( const QgsFeatureIds &fids )
 {
   if ( !mEditBuffer )
   {
-    QgsDebugMsg( "Cannot delete features (mEditBuffer==NULL)" );
+    QgsDebugMsgLevel( QStringLiteral( "Cannot delete features (mEditBuffer==NULL)" ), 1 );
     return false;
   }
 
@@ -2717,12 +2719,7 @@ bool QgsVectorLayer::addFeatures( QgsFeatureList &features, Flags )
 
 void QgsVectorLayer::setCoordinateSystem()
 {
-  QgsDebugMsgLevel( "----- Computing Coordinate System", 4 );
+  QgsDebugMsgLevel( QStringLiteral( "Computing Coordinate System" ), 4 );
-
-  //
-  // Get the layers project info and set up the QgsCoordinateTransform
-  // for this layer
-  //
 
   if ( isSpatial() )
   {
@@ -3708,14 +3705,14 @@ void QgsVectorLayer::readSldLabeling( const QDomNode &node )
   QDomElement userStyleElem = element.firstChildElement( QStringLiteral( "UserStyle" ) );
   if ( userStyleElem.isNull() )
   {
-    QgsDebugMsg( "Info: UserStyle element not found." );
+    QgsDebugMsgLevel( QStringLiteral( "Info: UserStyle element not found." ), 4 );
     return;
   }
 
   QDomElement featureTypeStyleElem = userStyleElem.firstChildElement( QStringLiteral( "FeatureTypeStyle" ) );
   if ( featureTypeStyleElem.isNull() )
   {
-    QgsDebugMsg( "Info: FeatureTypeStyle element not found." );
+    QgsDebugMsgLevel( QStringLiteral( "Info: FeatureTypeStyle element not found." ), 4 );
     return;
   }
 
@@ -3723,7 +3720,7 @@ void QgsVectorLayer::readSldLabeling( const QDomNode &node )
   QDomElement ruleElem = featureTypeStyleElem.lastChildElement( QStringLiteral( "Rule" ) );
   if ( ruleElem.isNull() )
   {
-    QgsDebugMsg( "Info: Rule element not found." );
+    QgsDebugMsgLevel( QStringLiteral( "Info: Rule element not found." ), 4 );
     return;
   }
 
@@ -3731,7 +3728,7 @@ void QgsVectorLayer::readSldLabeling( const QDomNode &node )
   QDomElement textSymbolizerElem = ruleElem.lastChildElement( QStringLiteral( "TextSymbolizer" ) );
   if ( textSymbolizerElem.isNull() )
   {
-    QgsDebugMsg( "Info: TextSymbolizer element not found." );
+    QgsDebugMsgLevel( QStringLiteral( "Info: TextSymbolizer element not found." ), 4 );
     return;
   }
 
@@ -3762,19 +3759,19 @@ void QgsVectorLayer::readSldLabeling( const QDomNode &node )
         }
         else
         {
-          QgsDebugMsg( "SLD label attribute error: " + exp.evalErrorString() );
+          QgsDebugMsgLevel( QStringLiteral( "SLD label attribute error: %1" ).arg( exp.evalErrorString() ), 3 );
         }
       }
     }
     else
     {
-      QgsDebugMsg( "Info: PropertyName element not found." );
+      QgsDebugMsgLevel( QStringLiteral( "Info: PropertyName element not found." ), 4 );
       return;
     }
   }
   else
   {
-    QgsDebugMsg( "Info: Label element not found." );
+    QgsDebugMsgLevel( QStringLiteral( "Info: Label element not found." ), 4 );
     return;
   }
 
@@ -4013,7 +4010,7 @@ QString QgsVectorLayer::htmlMetadata() const
   QgsWkbTypes::GeometryType type = geometryType();
   if ( type < 0 || type > QgsWkbTypes::NullGeometry )
   {
-    QgsDebugMsg( "Invalid vector type" );
+    QgsDebugMsgLevel( QStringLiteral( "Invalid vector type" ), 2 );
   }
   else
   {

src/core/qgsvectorlayer.h

@@ -1049,65 +1049,34 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer, public QgsExpressionConte
      * Adds a ring to polygon/multipolygon features
      * \param ring ring to add
      * \param featureId if specified, feature ID for feature ring was added to will be stored in this parameter
-     * \returns
+     * \returns QgsGeometry::OperationResult
-     *  0 in case of success,
-     *  1 problem with feature type,
-     *  2 ring not closed,
-     *  3 ring not valid,
-     *  4 ring crosses existing rings,
-     *  5 no feature found where ring can be inserted
-     *  6 layer not editable
      */
-    // TODO QGIS 3.0 returns an enum instead of a magic constant
+    QgsGeometry::OperationResult addRing( const QVector<QgsPointXY> &ring, QgsFeatureId *featureId = nullptr );
-    int addRing( const QVector<QgsPointXY> &ring, QgsFeatureId *featureId = nullptr );
 
     /**
      * Adds a ring to polygon/multipolygon features (takes ownership)
      * \param ring ring to add
      * \param featureId if specified, feature ID for feature ring was added to will be stored in this parameter
-     * \returns
+     * \returns QgsGeometry::OperationResult
-     *  0 in case of success
-     *  1 problem with feature type
-     *  2 ring not closed
-     *  6 layer not editable
      * \note available in Python as addCurvedRing
      */
-    // TODO QGIS 3.0 returns an enum instead of a magic constant
+    QgsGeometry::OperationResult addRing( QgsCurve *ring SIP_TRANSFER, QgsFeatureId *featureId = nullptr ) SIP_PYNAME( addCurvedRing );
-    int addRing( QgsCurve *ring SIP_TRANSFER, QgsFeatureId *featureId = nullptr ) SIP_PYNAME( addCurvedRing );
 
     /**
      * Adds a new part polygon to a multipart feature
-     * \returns
+     * \returns QgsGeometry::OperationResult
-     *   0 in case of success,
-     *   1 if selected feature is not multipart,
-     *   2 if ring is not a valid geometry,
-     *   3 if new polygon ring not disjoint with existing rings,
-     *   4 if no feature was selected,
-     *   5 if several features are selected,
-     *   6 if selected geometry not found
-     *   7 layer not editable
      */
-    // TODO QGIS 3.0 returns an enum instead of a magic constant
+    QgsGeometry::OperationResult addPart( const QList<QgsPointXY> &ring );
-    int addPart( const QList<QgsPointXY> &ring );
 
     /**
      * Adds a new part polygon to a multipart feature
-     * \returns
+     * \returns QgsGeometry::OperationResult
-     *   0 in case of success,
-     *   1 if selected feature is not multipart,
-     *   2 if ring is not a valid geometry,
-     *   3 if new polygon ring not disjoint with existing rings,
-     *   4 if no feature was selected,
-     *   5 if several features are selected,
-     *   6 if selected geometry not found
-     *   7 layer not editable
      * \note available in Python bindings as addPartV2
      */
-    // TODO QGIS 3.0 returns an enum instead of a magic constant
+    QgsGeometry::OperationResult addPart( const QgsPointSequence &ring ) SIP_PYNAME( addPartV2 );
-    int addPart( const QgsPointSequence &ring ) SIP_PYNAME( addPartV2 );
 
     //! \note available in Python as addCurvedPart
-    int addPart( QgsCurve *ring SIP_TRANSFER ) SIP_PYNAME( addCurvedPart );
+    QgsGeometry::OperationResult addPart( QgsCurve *ring SIP_TRANSFER ) SIP_PYNAME( addCurvedPart );
 
     /**
      * Translates feature by dx, dy
@@ -1122,23 +1091,17 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer, public QgsExpressionConte
      * Splits parts cut by the given line
      *  \param splitLine line that splits the layer features
      *  \param topologicalEditing true if topological editing is enabled
-     *  \returns
+     *  \returns QgsGeometry::OperationResult
-     *   0 in case of success,
-     *   4 if there is a selection but no feature split
      */
-    // TODO QGIS 3.0 returns an enum instead of a magic constant
+    QgsGeometry::OperationResult splitParts( const QVector<QgsPointXY> &splitLine, bool topologicalEditing = false );
-    int splitParts( const QVector<QgsPointXY> &splitLine, bool topologicalEditing = false );
 
     /**
      * Splits features cut by the given line
      *  \param splitLine line that splits the layer features
      *  \param topologicalEditing true if topological editing is enabled
-     *  \returns
+     *  \returns QgsGeometry::OperationResult
-     *   0 in case of success,
-     *   4 if there is a selection but no feature split
      */
-    // TODO QGIS 3.0 returns an enum instead of a magic constant
+    QgsGeometry::OperationResult splitFeatures( const QVector<QgsPointXY> &splitLine, bool topologicalEditing = false );
-    int splitFeatures( const QVector<QgsPointXY> &splitLine, bool topologicalEditing = false );
 
     /**
      * Adds topological points for every vertex of the geometry.

src/core/qgsvectorlayereditutils.cpp

@@ -301,7 +301,7 @@ QgsGeometry::OperationResult QgsVectorLayerEditUtils::splitFeatures( const QVect
     }
     else
     {
-      return QgsGeometry::InvalidInput;
+      return QgsGeometry::InvalidInputGeometryType;
     }
 
     if ( bBox.isEmpty() )
@@ -410,7 +410,7 @@ QgsGeometry::OperationResult QgsVectorLayerEditUtils::splitParts( const QVector<
     }
     else
     {
-      return QgsGeometry::InvalidInput;
+      return QgsGeometry::InvalidInputGeometryType;
     }
 
     if ( bBox.isEmpty() )