Don't ask for layer of multi-layer objects.

pcbnew/drc/drc_test_provider_misc.cpp

@@ -158,7 +158,7 @@ void DRC_TEST_PROVIDER_MISC::testDisabledLayers()
                     if( pad->GetAttribute() == PAD_ATTRIB::SMD
                             || pad->GetAttribute() == PAD_ATTRIB::CONN )
                     {
-                        if( disabledLayers.test( item->GetLayer() ) )
+                        if( disabledLayers.test( pad->GetPrincipalLayer() ) )
                             badLayer = item->GetLayer();
                     }
                     else

pcbnew/pad.cpp

@@ -208,6 +208,16 @@ PCB_LAYER_ID PAD::GetLayer() const
 }
 
 
+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;
+}
+
+
 bool PAD::FlashLayer( LSET aLayers ) const
 {
     for( auto layer : aLayers.Seq() )

pcbnew/pad.h

@@ -587,6 +587,11 @@ public:
 
     PCB_LAYER_ID GetLayer() const override;
 
+    /**
+     * @return the principal copper layer for SMD and CONN pads.
+     */
+    PCB_LAYER_ID GetPrincipalLayer() const;
+
     /**
      * Check to see if the pad should be flashed to any of the layers in the set.
      *

pcbnew/plugins/kicad/pcb_parser.cpp

@@ -5735,6 +5735,7 @@ ZONE* PCB_PARSER::parseZONE( BOARD_ITEM_CONTAINER* aParent )
                 }
                 else
                 {
+                    // for legacy, single-layer zones
                     filledLayer = zone->GetFirstLayer();
                 }