Skip newly-added footprints in connectivity

Fixes https://gitlab.com/kicad/code/kicad/-/issues/9892

pcbnew/connectivity/connectivity_algo.cpp

@@ -118,8 +118,6 @@ bool CN_CONNECTIVITY_ALGO::Add( BOARD_ITEM* aItem )
     if( !aItem->IsOnCopperLayer() )
         return false;
 
-    markItemNetAsDirty ( aItem );
-
     switch( aItem->Type() )
     {
     case PCB_NETINFO_T:
@@ -127,6 +125,10 @@ bool CN_CONNECTIVITY_ALGO::Add( BOARD_ITEM* aItem )
         break;
 
     case PCB_FOOTPRINT_T:
+    {
+        if( static_cast<FOOTPRINT*>( aItem )->GetAttributes() & FP_JUST_ADDED )
+            return false;
+
         for( PAD* pad : static_cast<FOOTPRINT*>( aItem )->Pads() )
         {
             if( m_itemMap.find( pad ) != m_itemMap.end() )
@@ -136,13 +138,22 @@ bool CN_CONNECTIVITY_ALGO::Add( BOARD_ITEM* aItem )
         }
 
         break;
+    }
 
     case PCB_PAD_T:
-        if( m_itemMap.find ( aItem ) != m_itemMap.end() )
+    {
+        if( FOOTPRINT* fp = dynamic_cast<FOOTPRINT*>( aItem->GetParentFootprint() ) )
+        {
+            if( fp->GetAttributes() & FP_JUST_ADDED )
+                return false;
+        }
+
+        if( m_itemMap.find( aItem ) != m_itemMap.end() )
             return false;
 
         add( m_itemList, static_cast<PAD*>( aItem ) );
         break;
+    }
 
     case PCB_TRACE_T:
         if( m_itemMap.find( aItem ) != m_itemMap.end() )
@@ -186,6 +197,8 @@ bool CN_CONNECTIVITY_ALGO::Add( BOARD_ITEM* aItem )
         return false;
     }
 
+    markItemNetAsDirty( aItem );
+
     return true;
 }
 

pcbnew/footprint.h

@@ -69,7 +69,8 @@ enum FOOTPRINT_ATTR_T
     FP_SMD                    = 0x0002,
     FP_EXCLUDE_FROM_POS_FILES = 0x0004,
     FP_EXCLUDE_FROM_BOM       = 0x0008,
-    FP_BOARD_ONLY             = 0x0010    // Footprint has no corresponding symbol
+    FP_BOARD_ONLY             = 0x0010,   // Footprint has no corresponding symbol
+    FP_JUST_ADDED             = 0x0020    // Footprint just added by netlist update
 };
 
 class FP_3DMODEL

pcbnew/netlist_reader/board_netlist_updater.cpp

@@ -178,6 +178,12 @@ FOOTPRINT* BOARD_NETLIST_UPDATER::addNewFootprint( COMPONENT* aComponent )
         footprint->SetParent( m_board );
         footprint->SetPosition( estimateFootprintInsertionPosition() );
 
+        // This flag is used to prevent connectivity from considering the footprint during its
+        // initial build after the footprint is committed, because we're going to immediately start
+        // a move operation on the footprint and don't want its pads to drive nets onto vias/tracks
+        // it happens to land on at the initial position.
+        footprint->SetAttributes( footprint->GetAttributes() | FP_JUST_ADDED );
+
         m_addedFootprints.push_back( footprint );
         m_commit.Add( footprint );
 

pcbnew/netlist_reader/netlist.cpp

@@ -114,7 +114,10 @@ void PCB_EDIT_FRAME::OnNetlistChanged( BOARD_NETLIST_UPDATER& aUpdater, bool* aR
     if( !newFootprints.empty() )
     {
         for( FOOTPRINT* footprint : newFootprints )
+        {
+            footprint->SetAttributes( footprint->GetAttributes() & ~FP_JUST_ADDED );
             GetToolManager()->RunAction( PCB_ACTIONS::selectItem, true, footprint );
+        }
 
         *aRunDragCommand = true;