[OGR provider] Make feature iterator work on GeometryCollection sublayers

When trying to reproduce http://hub.qgis.org/issues/10485, I noticed a regression.
Now attribute table no longer shows features with OGR GeometryCollection.

Fixes also issues where sublayer geometry type is too strict regarding 2D vs 2.5D
geometry types.

Fixes #15675

Author: rouault

src/providers/ogr/qgsogrfeatureiterator.cpp

@@ -311,8 +311,13 @@ bool QgsOgrFeatureIterator::readFeature( OGRFeatureH fet, QgsFeature& feature )
     else
       feature.clearGeometry();
 
-    if (( useIntersect && ( !feature.hasGeometry() || !feature.geometry().intersects( mRequest.filterRect() ) ) )
-        || ( geometryTypeFilter && ( !feature.hasGeometry() || QgsOgrProvider::ogrWkbSingleFlatten(( OGRwkbGeometryType )feature.geometry().wkbType() ) != mSource->mOgrGeometryTypeFilter ) ) )
+    if ( mSource->mOgrGeometryTypeFilter == wkbGeometryCollection &&
+         geom && wkbFlatten( OGR_G_GetGeometryType( geom ) ) == wkbGeometryCollection )
+    {
+      // OK
+    }
+    else if (( useIntersect && ( !feature.hasGeometry() || !feature.geometry().intersects( mRequest.filterRect() ) ) )
+             || ( geometryTypeFilter && ( !feature.hasGeometry() || QgsOgrProvider::ogrWkbSingleFlatten(( OGRwkbGeometryType )feature.geometry().wkbType() ) != mSource->mOgrGeometryTypeFilter ) ) )
     {
       OGR_F_Destroy( fet );
       return false;
@@ -359,7 +364,8 @@ QgsOgrFeatureSource::QgsOgrFeatureSource( const QgsOgrProvider* p )
     mFieldsWithoutFid.append( mFields.at( i ) );
   mDriverName = p->ogrDriverName;
   mFirstFieldIsFid = p->mFirstFieldIsFid;
-  mOgrGeometryTypeFilter = wkbFlatten( p->mOgrGeometryTypeFilter );
+  mOgrGeometryTypeFilter = QgsOgrProvider::ogrWkbSingleFlatten( p->mOgrGeometryTypeFilter );
+  QgsDebugMsg( QString( "mOgrGeometryTypeFilter: %1" ).arg( mOgrGeometryTypeFilter ) );
   QgsOgrConnPool::instance()->ref( mDataSource );
 }
 

src/providers/ogr/qgsogrprovider.cpp

@@ -3155,13 +3155,16 @@ void QgsOgrProvider::recalculateFeatureCount()
     setRelevantFields( ogrLayer, true, QgsAttributeList() );
     OGR_L_ResetReading( ogrLayer );
     OGRFeatureH fet;
+    const OGRwkbGeometryType flattenGeomTypeFilter =
+      QgsOgrProvider::ogrWkbSingleFlatten( mOgrGeometryTypeFilter );
     while (( fet = OGR_L_GetNextFeature( ogrLayer ) ) )
     {
       OGRGeometryH geom = OGR_F_GetGeometryRef( fet );
       if ( geom )
       {
         OGRwkbGeometryType gType = OGR_G_GetGeometryType( geom );
-        if ( gType == mOgrGeometryTypeFilter ) mFeaturesCounted++;
+        gType = QgsOgrProvider::ogrWkbSingleFlatten( gType );
+        if ( gType == flattenGeomTypeFilter ) mFeaturesCounted++;
       }
       OGR_F_Destroy( fet );
     }

tests/src/python/test_provider_ogr.py

@@ -221,5 +221,24 @@ def testNoDanglingFileDescriptorAfterCloseVariant2(self):
         os.unlink(datasource)
         self.assertFalse(os.path.exists(datasource))
 
+    def testGeometryCollection(self):
+        ''' Test that we can at least retrieves attribute of features with geometry collection '''
+
+        datasource = os.path.join(self.basetestpath, 'testGeometryCollection.csv')
+        with open(datasource, 'wt') as f:
+            f.write('id,WKT\n')
+            f.write('1,POINT Z(2 49 0)\n')
+            f.write('2,GEOMETRYCOLLECTION Z (POINT Z (2 49 0))\n')
+
+        vl = QgsVectorLayer('{}|layerid=0|geometrytype=GeometryCollection'.format(datasource), 'test', 'ogr')
+        self.assertTrue(vl.isValid())
+        self.assertTrue(vl.featureCount(), 1)
+        values = [f['id'] for f in vl.getFeatures()]
+        self.assertEqual(values, ['2'])
+        del vl
+
+        os.unlink(datasource)
+        self.assertFalse(os.path.exists(datasource))
+
 if __name__ == '__main__':
     unittest.main()