Fix some layer handling issues.

pcbnew/drc/drc_test_provider_misc.cpp

@@ -163,7 +163,7 @@ void DRC_TEST_PROVIDER_MISC::testDisabledLayers()
                     }
                     else
                     {
-                        // Through hole pad is on whatever layers there are.
+                        // Through hole pad pierces all physical layers.
                     }
                 }
                 else if( item->Type() == PCB_VIA_T )

pcbnew/edit_zone_helpers.cpp

@@ -113,7 +113,7 @@ void PCB_EDIT_FRAME::Edit_Zone_Params( ZONE* aZone )
 bool BOARD::TestZoneIntersection( ZONE* aZone1, ZONE* aZone2 )
 {
     // see if areas are on same layer
-    if( aZone1->GetLayer() != aZone2->GetLayer() )
+    if( !( aZone1->GetLayerSet() & aZone2->GetLayerSet() ).any() )
         return false;
 
     SHAPE_POLY_SET* poly1 = aZone1->Outline();

pcbnew/pad.cpp

@@ -196,6 +196,7 @@ bool PAD::IsFlipped() const
 {
     if( GetParent() &&  GetParent()->GetLayer() == B_Cu )
         return true;
+
     return false;
 }
 
@@ -210,9 +211,8 @@ PCB_LAYER_ID PAD::GetPrincipalLayer() const
 {
     if( m_attribute == PAD_ATTRIB::SMD || m_attribute == PAD_ATTRIB::CONN )
         return m_layer;
-
-    wxFAIL_MSG( wxT( "Non-SMD/CONN pads have no principal layer." ) );
-    return m_layer;
+    else
+        return GetLayerSet().Seq().front();
 }
 
 

pcbnew/tools/board_editor_control.cpp

@@ -1459,7 +1459,7 @@ int BOARD_EDITOR_CONTROL::ZoneMerge( const TOOL_EVENT& aEvent )
             continue;
         }
 
-        if( curr_area->GetLayer() != firstZone->GetLayer() )
+        if( curr_area->GetLayerSet() != firstZone->GetLayerSet() )
         {
             wxLogMessage( _( "Some zone layer sets did not match and were not merged." ) );
             continue;