Fix crash on net highlighting

When navigating to a sheet without the highlighted net, there was a
chance for an uninitialized pointer deref.  This also gathers the
highlighted nets into the navigator as well as their subsuming buses

Fixes https://gitlab.com/kicad/code/kicad/-/issues/18419

eeschema/connection_graph.cpp

@@ -3111,10 +3111,10 @@ CONNECTION_SUBGRAPH* CONNECTION_GRAPH::GetSubgraphForItem( SCH_ITEM* aItem ) con
 }
 
 
-const std::vector<CONNECTION_SUBGRAPH*>
+const std::vector<CONNECTION_SUBGRAPH*>&
 CONNECTION_GRAPH::GetAllSubgraphs( const wxString& aNetName ) const
 {
-    std::vector<CONNECTION_SUBGRAPH*> subgraphs;
+    static const std::vector<CONNECTION_SUBGRAPH*> subgraphs;
 
     auto it = m_net_name_to_subgraphs_map.find( aNetName );
 

eeschema/connection_graph.h

@@ -441,7 +441,7 @@ public:
 
     CONNECTION_SUBGRAPH* GetSubgraphForItem( SCH_ITEM* aItem ) const;
 
-    const std::vector<CONNECTION_SUBGRAPH*> GetAllSubgraphs( const wxString& aNetName ) const;
+    const std::vector<CONNECTION_SUBGRAPH*>& GetAllSubgraphs( const wxString& aNetName ) const;
 
     /**
      * Return the fully-resolved netname for a given subgraph.

eeschema/net_navigator.cpp

@@ -205,8 +205,27 @@ void SCH_EDIT_FRAME::MakeNetNavigatorNode( const wxString& aNetName, wxTreeItemI
     wxCHECK( connectionGraph, /* void */ );
 
     wxString sheetPathPrefix;
-    const std::vector<CONNECTION_SUBGRAPH*> subgraphs =
-            connectionGraph->GetAllSubgraphs( aNetName );
+    std::set<CONNECTION_SUBGRAPH*> subgraphs;
+
+    {
+        const std::vector<CONNECTION_SUBGRAPH*>& tmp = connectionGraph->GetAllSubgraphs( aNetName );
+        subgraphs.insert( tmp.begin(), tmp.end() );
+    }
+
+    for( CONNECTION_SUBGRAPH* sg : subgraphs )
+    {
+        for( const auto& [_, bus_sgs] : sg->GetBusParents() )
+        {
+            for( const CONNECTION_SUBGRAPH* bus_sg : bus_sgs )
+            {
+                const std::vector<CONNECTION_SUBGRAPH*>& tmp =
+                        connectionGraph->GetAllSubgraphs( bus_sg->GetNetName() );
+                subgraphs.insert( tmp.begin(), tmp.end() );
+            }
+        }
+    }
+
+    std::map<wxString, wxTreeItemId> sheetIds;
 
     for( const CONNECTION_SUBGRAPH* subGraph : subgraphs )
     {
@@ -222,7 +241,18 @@ void SCH_EDIT_FRAME::MakeNetNavigatorNode( const wxString& aNetName, wxTreeItemI
 
         bool stripTrailingSeparator = !sheetPath.Last()->IsRootSheet();
         wxString txt =  sheetPath.PathHumanReadable( true, stripTrailingSeparator );
-        wxTreeItemId sheetId = m_netNavigator->AppendItem( aParentId, txt, -1, -1, itemData );
+
+        wxTreeItemId sheetId;
+
+        if( auto sheetIdIt = sheetIds.find( txt ); sheetIdIt != sheetIds.end() )
+        {
+            sheetId = sheetIdIt->second;
+        }
+        else
+        {
+            sheetIds[txt] = m_netNavigator->AppendItem( aParentId, txt, -1, -1, itemData );
+            sheetId = sheetIds[txt];
+        }
 
         if( aSelection && *aSelection == *itemData )
             m_netNavigator->SelectItem( sheetId );
@@ -252,8 +282,12 @@ void SCH_EDIT_FRAME::MakeNetNavigatorNode( const wxString& aNetName, wxTreeItemI
                 m_netNavigator->SelectItem( id );
             }
         }
+
+        m_netNavigator->SortChildren( sheetId );
     }
 
+    // Sort the items in the tree control alphabetically
+    m_netNavigator->SortChildren( aParentId );
     m_netNavigator->Expand( aParentId );
 }
 

eeschema/tools/sch_editor_control.cpp

@@ -1088,39 +1088,41 @@ int SCH_EDITOR_CONTROL::UpdateNetHighlighting( const TOOL_EVENT& aEvent )
     {
         connNames.emplace( selectedName );
 
-        CONNECTION_SUBGRAPH* sg = connectionGraph->FindSubgraphByName( selectedName, sheetPath );
-
-        if( sg && m_highlightBusMembers )
+        if( CONNECTION_SUBGRAPH* sg =
+                    connectionGraph->FindSubgraphByName( selectedName, sheetPath ) )
         {
-            for( const SCH_ITEM* item : sg->GetItems() )
+            if( m_highlightBusMembers )
             {
-                wxCHECK2( item, continue );
-
-                if( SCH_CONNECTION* connection = item->Connection() )
+                for( const SCH_ITEM* item : sg->GetItems() )
                 {
-                    for( const std::shared_ptr<SCH_CONNECTION>& member : connection->AllMembers() )
+                    wxCHECK2( item, continue );
+
+                    if( SCH_CONNECTION* connection = item->Connection() )
                     {
-                        if( member )
-                            connNames.emplace( member->Name() );
+                        for( const std::shared_ptr<SCH_CONNECTION>& member :
+                             connection->AllMembers() )
+                        {
+                            if( member )
+                                connNames.emplace( member->Name() );
+                        }
                     }
                 }
             }
         }
 
-        // Highlight the buses that contain the selected net
-        for( const auto& [_, bus_sgs] : sg->GetBusParents() )
+        // Place all bus names that are connected to the selected net in the set, regardless of
+        // their sheet. This ensures that nets that are connected to a bus on a different sheet
+        // get their buses highlighted as well.
+        for( CONNECTION_SUBGRAPH* sg : connectionGraph->GetAllSubgraphs( selectedName ) )
         {
-            for( const CONNECTION_SUBGRAPH* bus_sg : bus_sgs )
+            for( const auto& [_, bus_sgs] : sg->GetBusParents() )
             {
-                for( const SCH_ITEM* item : bus_sg->GetItems() )
+                for( CONNECTION_SUBGRAPH* bus_sg : bus_sgs )
                 {
-                    if( !item || !item->IsType( { SCH_ITEM_LOCATE_BUS_T } ) )
-                        continue;
-
-                    if( SCH_CONNECTION* connection = item->Connection() )
-                        connNames.emplace( connection->Name() );
+                    connNames.emplace( bus_sg->GetNetName() );
                 }
             }
+
         }
     }