Properties: specialize layer setting for footprints

Fixes https://gitlab.com/kicad/code/kicad/-/issues/12480

common/properties/property_mgr.cpp

@@ -111,7 +111,7 @@ void PROPERTY_MANAGER::AddProperty( PROPERTY_BASE* aProperty )
 
 void PROPERTY_MANAGER::ReplaceProperty( size_t aBase, const wxString& aName, PROPERTY_BASE* aNew )
 {
-    wxASSERT( aBase == aNew->BaseHash() );
+    wxASSERT( aBase == aNew->BaseHash() || IsOfType( aNew->OwnerHash(), aBase ) );
     CLASS_DESC& classDesc = getClass( aNew->OwnerHash() );
     classDesc.m_replaced.insert( std::make_pair( aBase, aName ) );
     AddProperty( aNew );

pcbnew/footprint.cpp

@@ -1559,6 +1559,15 @@ void FOOTPRINT::Rotate( const VECTOR2I& aRotCentre, const EDA_ANGLE& aAngle )
 }
 
 
+void FOOTPRINT::SetLayerAndFlip( PCB_LAYER_ID aLayer )
+{
+    wxASSERT( aLayer == F_Cu || aLayer == B_Cu );
+
+    if( aLayer != GetLayer() )
+        Flip( GetPosition(), true );
+}
+
+
 void FOOTPRINT::Flip( const VECTOR2I& aCentre, bool aFlipLeftRight )
 {
     // Move footprint to its final position:
@@ -1578,7 +1587,7 @@ void FOOTPRINT::Flip( const VECTOR2I& aCentre, bool aFlipLeftRight )
     SetPosition( finalPos );
 
     // Flip layer
-    SetLayer( FlipLayer( GetLayer() ) );
+    BOARD_ITEM::SetLayer( FlipLayer( GetLayer() ) );
 
     // Reverse mirror orientation.
     m_orient = -m_orient;
@@ -2829,10 +2838,11 @@ static struct FOOTPRINT_DESC
         propMgr.InheritsAfter( TYPE_HASH( FOOTPRINT ), TYPE_HASH( BOARD_ITEM ) );
         propMgr.InheritsAfter( TYPE_HASH( FOOTPRINT ), TYPE_HASH( BOARD_ITEM_CONTAINER ) );
 
-        auto layer = new PROPERTY_ENUM<FOOTPRINT, PCB_LAYER_ID, BOARD_ITEM>( _HKI( "Layer" ),
-                    &FOOTPRINT::SetLayer, &FOOTPRINT::GetLayer );
+        auto layer = new PROPERTY_ENUM<FOOTPRINT, PCB_LAYER_ID>( _HKI( "Layer" ),
+                    &FOOTPRINT::SetLayerAndFlip, &FOOTPRINT::GetLayer );
         layer->SetChoices( fpLayers );
         propMgr.ReplaceProperty( TYPE_HASH( BOARD_ITEM ), _HKI( "Layer" ), layer );
+
         propMgr.AddProperty( new PROPERTY<FOOTPRINT, wxString>( _HKI( "Reference" ),
                     &FOOTPRINT::SetReference, &FOOTPRINT::GetReferenceAsString ) );
         propMgr.AddProperty( new PROPERTY<FOOTPRINT, wxString>( _HKI( "Value" ),

pcbnew/footprint.h

@@ -190,6 +190,15 @@ public:
     void SetOrientation( const EDA_ANGLE& aNewAngle );
     EDA_ANGLE GetOrientation() const { return m_orient; }
 
+    /**
+     * Used as Layer property setter -- performs a flip if necessary to set the footprint layer
+     * @param aLayer is the target layer (F_Cu or B_Cu)
+     */
+    void SetLayerAndFlip( PCB_LAYER_ID aLayer );
+
+    // to make property magic work
+    PCB_LAYER_ID GetLayer() const override { return BOARD_ITEM::GetLayer(); }
+
     // For property system:
     void SetOrientationDegrees( double aOrientation )
     {