1. placement_finder.cpp

    fixed 'for' loops to work correctly when geom->num_points() < 2
    always use prefix increment even for built-in types (good practice!)
    e.g ++i 

2. agg_renderer.cpp 
    check for number points in geometries when 
    applying text/shield_symbolizer.

src/agg_renderer.cpp

@@ -332,7 +332,7 @@ namespace mapnik
                                    proj_transform const& prj_trans)
     {
         geometry_ptr const& geom=feature.get_geometry();
-        if (geom)
+        if (geom && geom->num_points() > 0)
         {
             std::wstring text = to_unicode(feature[sym.get_name()].to_string());
             boost::shared_ptr<ImageData32> const& data = sym.get_data();
@@ -492,7 +492,7 @@ namespace mapnik
     {
         geometry_ptr const& geom=feature.get_geometry();
 
-        if (geom)
+        if (geom && geom->num_points() > 0)
         {
             std::wstring text = to_unicode(feature[sym.get_name()].to_string());
             if (text.length() > 0)

src/placement_finder.cpp

@@ -75,7 +75,8 @@ namespace mapnik
 
         shape_path.rewind(0);
         shape_path.vertex(&new_x,&new_y);
-        for (unsigned i = 0; i < geom->num_points() - 1; i++)
+        unsigned num_points =  geom->num_points();
+        for (unsigned i = 1; i < num_points; ++i)
         {
             double dx, dy;
 
@@ -113,13 +114,13 @@ namespace mapnik
             shape_path.vertex(&old_x,&old_y);
 
             total_distance_ = 0.0;
-
-            for (unsigned i = 0; i < geom->num_points() - 1; i++)
+
+            unsigned num_points = geom->num_points();
+            for (unsigned i = 1; i < num_points ; ++i)
             {
                 double dx, dy;
-
                 shape_path.vertex(&new_x,&new_y);
-
+                
                 dx = new_x - old_x;
                 dy = new_y - old_y;
 
@@ -330,7 +331,8 @@ namespace mapnik
         p->shape_path.vertex(&new_x,&new_y);
         old_x = new_x;
         old_y = new_y;
-        for (unsigned i = 0; i < p->geom->num_points() - 1; i++)
+        unsigned num_points = geom->num_points();
+        for (unsigned i = 1; i < num_points; ++i)
         {
             double dx, dy;