Remove unused nets when updating PCB.

Fixes https://gitlab.com/kicad/code/kicad/issues/4247

pcbnew/board_commit.cpp

@@ -164,7 +164,9 @@ void BOARD_COMMIT::Push( const wxString& aMessage, bool aCreateUndoEntry, bool a
                         board->Add( boardItem );        // handles connectivity
                 }
 
+                if( boardItem->Type() != PCB_NETINFO_T )
                     view->Add( boardItem );
+
                 break;
             }
 
@@ -240,6 +242,12 @@ void BOARD_COMMIT::Push( const wxString& aMessage, bool aCreateUndoEntry, bool a
                 }
                 break;
 
+                // Metadata items
+                case PCB_NETINFO_T:
+                    if( !( changeFlags & CHT_DONE ) )
+                        board->Remove( boardItem );
+                    break;
+
                 default:                        // other types do not need to (or should not) be handled
                     wxASSERT( false );
                     break;

pcbnew/netinfo.h

@@ -460,6 +460,8 @@ public:
      * Removes a new from the net list.
      */
     void RemoveNet( NETINFO_ITEM* aNet );
+    void RemoveUnusedNets();
+
     /**
      * Function GetPadCount
      * @return the number of pads in board

pcbnew/netinfo_list.cpp

@@ -108,6 +108,24 @@ void NETINFO_LIST::RemoveNet( NETINFO_ITEM* aNet )
 }
 
 
+void NETINFO_LIST::RemoveUnusedNets()
+{
+    NETCODES_MAP existingNets = m_netCodes;
+
+    m_netCodes.clear();
+    m_netNames.clear();
+
+    for( std::pair<const int, NETINFO_ITEM*> item : existingNets )
+    {
+        if( item.second->IsCurrent() )
+        {
+            m_netNames.insert( std::make_pair( item.second->GetNetname(), item.second ) );
+            m_netCodes.insert( std::make_pair( item.first, item.second ) );
+        }
+    }
+}
+
+
 void NETINFO_LIST::AppendNet( NETINFO_ITEM* aNewElement )
 {
     // if there is a net with such name then just assign the correct number

pcbnew/netlist_reader/board_netlist_updater.cpp

@@ -827,13 +827,25 @@ bool BOARD_NETLIST_UPDATER::UpdateNetlist( NETLIST& aNetlist )
 
     if( !m_isDryRun )
     {
-        m_commit.Push( _( "Update netlist" ) );
         m_board->GetConnectivity()->Build( m_board );
         testConnectivity( aNetlist );
 
         // Now the connectivity data is rebuilt, we can delete single pads nets
         if( m_deleteSinglePadNets )
             deleteSinglePadNets();
+
+        for( NETINFO_ITEM* net : m_board->GetNetInfo() )
+        {
+            if( !net->IsCurrent() )
+            {
+                msg.Printf( _( "Remove unused net \"%s\"." ), net->GetNetname() );
+                m_reporter->Report( msg, RPT_SEVERITY_ACTION );
+                m_commit.Removed( net );
+            }
+        }
+
+        m_board->GetNetInfo().RemoveUnusedNets();
+        m_commit.Push( _( "Update netlist" ) );
     }
     else if( m_deleteSinglePadNets && !m_newFootprintsCount )
         // We can delete single net pads in dry run mode only if no new footprints

pcbnew/undo_redo.cpp

@@ -28,9 +28,7 @@
 #include <functional>
 using namespace std::placeholders;
 #include <fctsys.h>
-#include <class_draw_panel_gal.h>
 #include <macros.h>
-#include <pcbnew.h>
 #include <pcb_edit_frame.h>
 #include <class_board.h>
 #include <class_track.h>
@@ -39,8 +37,6 @@ using namespace std::placeholders;
 #include <class_pcb_target.h>
 #include <class_module.h>
 #include <class_dimension.h>
-#include <class_zone.h>
-#include <class_edge_mod.h>
 #include <origin_viewitem.h>
 #include <connectivity/connectivity_data.h>
 #include <pcbnew_settings.h>
@@ -49,7 +45,6 @@ using namespace std::placeholders;
 #include <tools/selection_tool.h>
 #include <tools/pcbnew_control.h>
 #include <tools/pcb_editor_control.h>
-#include <view/view.h>
 #include <ws_proxy_undo_item.h>
 
 /* Functions to undo and redo edit commands.
@@ -483,13 +478,19 @@ void PCB_BASE_EDIT_FRAME::PutDataInPreviousState( PICKED_ITEMS_LIST* aList, bool
         case UR_NEW:        /* new items are deleted */
             aList->SetPickedItemStatus( UR_DELETED, ii );
             GetModel()->Remove( (BOARD_ITEM*) eda_item );
+
+            if( eda_item->Type() != PCB_NETINFO_T )
                 view->Remove( eda_item );
+
             break;
 
         case UR_DELETED:    /* deleted items are put in List, as new items */
             aList->SetPickedItemStatus( UR_NEW, ii );
             GetModel()->Add( (BOARD_ITEM*) eda_item );
+
+            if( eda_item->Type() != PCB_NETINFO_T )
                 view->Add( eda_item );
+
             break;
 
         case UR_MOVED: