From c16e86be9a241383cdb25f32b73f8c5986b7e69f Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Fri, 16 Sep 2022 22:48:33 +0100
Subject: [PATCH] Use router's connectivity algorithm, not CONNECTIVITY_DATA's.

Fixes https://gitlab.com/kicad/code/kicad/issues/10745

(cherry picked from commit 107f4091066c370be9cf8ee26688798eab4b3433)
---
 pcbnew/tools/edit_tool.cpp | 58 ++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 30 deletions(-)

diff --git a/pcbnew/tools/edit_tool.cpp b/pcbnew/tools/edit_tool.cpp
index ca3640ec91..092b86c5cf 100644
--- a/pcbnew/tools/edit_tool.cpp
+++ b/pcbnew/tools/edit_tool.cpp
@@ -293,47 +293,45 @@ int EDIT_TOOL::Drag( const TOOL_EVENT& aEvent )
                 if( aCollector.GetCount() > 1 )
                     sTool->GuessSelectionCandidates( aCollector, aPt );
 
-                // If we have a knee between two segments, or a via attached to two segments,
-                // then drop the selection to a single item.
-                static KICAD_T          trackTypes[] = { PCB_VIA_T, PCB_TRACE_T, PCB_ARC_T, EOT };
+                /*
+                 * If we have a knee between two segments, or a via attached to two segments,
+                 * then drop the selection to a single item.
+                 */
+
                 std::vector<PCB_TRACK*> tracks;
                 std::vector<PCB_TRACK*> vias;
 
                 for( EDA_ITEM* item : aCollector )
                 {
-                    if( item->IsType( trackTypes ) )
-                        tracks.push_back( static_cast<PCB_TRACK*>( item ) );
-                    else if( item->Type() == PCB_VIA_T )
-                        vias.push_back( static_cast<PCB_TRACK*>( item ) );
+                    if( PCB_TRACK* track = dynamic_cast<PCB_TRACK*>( item ) )
+                    {
+                        if( track->Type() == PCB_VIA_T )
+                            vias.push_back( track );
+                        else
+                            tracks.push_back( track );
+                    }
                 }
 
-                if( tracks.size() == 2 )
+                auto connected = []( PCB_TRACK* track, const wxPoint& pt )
+                                 {
+                                     return track->GetStart() == pt || track->GetEnd() == pt;
+                                 };
+
+                if( tracks.size() == 2 && vias.size() == 0 )
                 {
-                    const BOARD*                       board = tracks[0]->GetBoard();
-                    std::shared_ptr<CONNECTIVITY_DATA> c = board->GetConnectivity();
-                    std::vector<BOARD_CONNECTED_ITEM*> cItems;
-
-                    int accuracy = KiROUND( 5 * aCollector.GetGuide()->OnePixelInIU() );
-
-                    if( vias.size() == 1 )
+                    if( connected( tracks[0], tracks[1]->GetStart() )
+                            || connected( tracks[0], tracks[1]->GetEnd() ) )
                     {
-                        cItems = c->GetConnectedItemsAtAnchor( vias[0], aPt, trackTypes,
-                                                               vias[0]->GetWidth() / 2 + accuracy );
-
-                        if( alg::contains( cItems, tracks[0] )
-                                && alg::contains( cItems, tracks[1] ) )
-                        {
-                            aCollector.Remove( tracks[0] );
-                            aCollector.Remove( tracks[1] );
-                        }
+                        aCollector.Remove( tracks[1] );
                     }
-                    else if( vias.size() == 0 )
+                }
+                else if( tracks.size() == 2 && vias.size() == 1 )
+                {
+                    if( connected( tracks[0], vias[0]->GetPosition() )
+                            && connected( tracks[1], vias[0]->GetPosition() ) )
                     {
-                        cItems = c->GetConnectedItemsAtAnchor( tracks[0], aPt, trackTypes,
-                                                               tracks[0]->GetWidth() / 2 + accuracy );
-
-                        if( alg::contains( cItems, tracks[1] ) )
-                            aCollector.Remove( tracks[1] );
+                        aCollector.Remove( tracks[0] );
+                        aCollector.Remove( tracks[1] );
                     }
                 }
             },