Add some safety to layer swapping

Fixes https://gitlab.com/kicad/code/kicad/-/issues/17371

pcbnew/dialogs/dialog_swap_layers.cpp

@@ -27,6 +27,7 @@
 #include <kiplatform/ui.h>
 #include <widgets/wx_grid.h>
 #include <board.h>
+#include <magic_enum.hpp>
 #include "dialog_swap_layers.h"
 
 
@@ -67,7 +68,8 @@ public:
 };
 
 
-DIALOG_SWAP_LAYERS::DIALOG_SWAP_LAYERS( PCB_BASE_EDIT_FRAME* aParent, PCB_LAYER_ID* aArray ) :
+DIALOG_SWAP_LAYERS::DIALOG_SWAP_LAYERS( PCB_BASE_EDIT_FRAME* aParent,
+                                        std::map<PCB_LAYER_ID, PCB_LAYER_ID>& aArray ) :
     DIALOG_SWAP_LAYERS_BASE( aParent ),
     m_parent( aParent ),
     m_layerDestinations( aArray )
@@ -133,10 +135,20 @@ bool DIALOG_SWAP_LAYERS::TransferDataFromWindow()
 
     for( size_t layer = 0; layer < PCB_LAYER_ID_COUNT; ++layer )
     {
+        std::optional<PCB_LAYER_ID> src = magic_enum::enum_cast<PCB_LAYER_ID>( layer );
+        wxCHECK2( src.has_value(), continue );
+
         if( enabledCopperLayers.test( layer ) )
-            m_layerDestinations[ layer ] = (PCB_LAYER_ID) table->GetValueAsLong( row++, 1 );
+        {
+            std::optional<PCB_LAYER_ID> dest =
+                    magic_enum::enum_cast<PCB_LAYER_ID>( table->GetValueAsLong( row++, 1 ) );
+            wxCHECK2( dest.has_value(),  m_layerDestinations[ *src ] = *dest );
+            m_layerDestinations[ *src ] = *dest;
+        }
         else
-            m_layerDestinations[ layer ] = (PCB_LAYER_ID) layer;
+        {
+            m_layerDestinations[ *src ] = *src;
+        }
     }
 
     return true;

pcbnew/dialogs/dialog_swap_layers.h

@@ -33,7 +33,8 @@ class LAYER_GRID_TABLE;
 class DIALOG_SWAP_LAYERS : public DIALOG_SWAP_LAYERS_BASE
 {
 public:
-    DIALOG_SWAP_LAYERS( PCB_BASE_EDIT_FRAME* aParent, PCB_LAYER_ID* aArray );
+    DIALOG_SWAP_LAYERS( PCB_BASE_EDIT_FRAME* aParent,
+                        std::map<PCB_LAYER_ID, PCB_LAYER_ID>& aArray );
     ~DIALOG_SWAP_LAYERS() override;
 
 private:
@@ -45,7 +46,7 @@ private:
     void adjustGridColumns();
 
     PCB_BASE_EDIT_FRAME* m_parent;
-    PCB_LAYER_ID*        m_layerDestinations;
+    std::map<PCB_LAYER_ID, PCB_LAYER_ID>& m_layerDestinations;
 
     LAYER_GRID_TABLE*    m_gridTable;
 };

pcbnew/tools/global_edit_tool.cpp

@@ -111,12 +111,15 @@ int GLOBAL_EDIT_TOOL::ExchangeFootprints( const TOOL_EVENT& aEvent )
 }
 
 
-bool GLOBAL_EDIT_TOOL::swapBoardItem( BOARD_ITEM* aItem, PCB_LAYER_ID* aLayerMap )
+bool GLOBAL_EDIT_TOOL::swapBoardItem( BOARD_ITEM* aItem,
+                                      std::map<PCB_LAYER_ID, PCB_LAYER_ID>& aLayerMap )
 {
-    if( aLayerMap[ aItem->GetLayer() ] != aItem->GetLayer() )
+    PCB_LAYER_ID original = aItem->GetLayer();
+
+    if( aLayerMap.count( original ) && aLayerMap.at( original ) != original )
     {
         m_commit->Modify( aItem );
-        aItem->SetLayer( aLayerMap[ aItem->GetLayer() ] );
+        aItem->SetLayer( aLayerMap.at( original ) );
         frame()->GetCanvas()->GetView()->Update( aItem, KIGFX::GEOMETRY );
         return true;
     }
@@ -127,7 +130,7 @@ bool GLOBAL_EDIT_TOOL::swapBoardItem( BOARD_ITEM* aItem, PCB_LAYER_ID* aLayerMap
 
 int GLOBAL_EDIT_TOOL::SwapLayers( const TOOL_EVENT& aEvent )
 {
-    PCB_LAYER_ID layerMap[PCB_LAYER_ID_COUNT];
+    std::map<PCB_LAYER_ID, PCB_LAYER_ID> layerMap;
 
     DIALOG_SWAP_LAYERS dlg( frame(), layerMap );
 

pcbnew/tools/global_edit_tool.h

@@ -66,7 +66,7 @@ public:
     int ZonesManager( const TOOL_EVENT& aEvent );
 
 private:
-    bool swapBoardItem( BOARD_ITEM* aItem, PCB_LAYER_ID* aLayerMap );
+    bool swapBoardItem( BOARD_ITEM* aItem, std::map<PCB_LAYER_ID, PCB_LAYER_ID>& aLayerMap );
 
     ///< Set up handlers for various events.
     void setTransitions() override;