Index: core/qgsgeometryvertexindex.cpp
===================================================================
--- core/qgsgeometryvertexindex.cpp	(revision 5017)
+++ core/qgsgeometryvertexindex.cpp	(working copy)
@@ -31,6 +31,7 @@
 QgsGeometryVertexIndex & QgsGeometryVertexIndex::operator=( QgsGeometryVertexIndex const & rhs )
 {
   mIndex = rhs.mIndex;
+  return *this;
 }
 
 QgsGeometryVertexIndex::~QgsGeometryVertexIndex()