Tighten up layer handling for LIB_SYMBOL.

We have to draw the parent symbol on the union of all layers that
its children might reside on, but we only want to draw each child
on its layers.

And we need to make sure LAYER_PRIVATE_NOTES gets into the layers
order list.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/13943

eeschema/lib_symbol.cpp

@@ -1121,13 +1121,15 @@ const BOX2I LIB_SYMBOL::GetUnitBoundingBox( int aUnit, int aConvert,
 
 void LIB_SYMBOL::ViewGetLayers( int aLayers[], int& aCount ) const
 {
-    aCount      = 6;
-    aLayers[0]  = LAYER_DEVICE;
-    aLayers[1]  = LAYER_DEVICE_BACKGROUND;
-    aLayers[2]  = LAYER_REFERENCEPART;
-    aLayers[3]  = LAYER_VALUEPART;
-    aLayers[4]  = LAYER_FIELDS;
-    aLayers[5]  = LAYER_SELECTION_SHADOWS;
+    aCount = 0;
+    aLayers[ aCount++ ] = LAYER_DEVICE;
+    aLayers[ aCount++ ] = LAYER_DEVICE_BACKGROUND;
+    aLayers[ aCount++ ] = LAYER_REFERENCEPART;
+    aLayers[ aCount++ ] = LAYER_VALUEPART;
+    aLayers[ aCount++ ] = LAYER_FIELDS;
+    aLayers[ aCount++ ] = LAYER_PRIVATE_NOTES;
+    aLayers[ aCount++ ] = LAYER_NOTES_BACKGROUND;
+    aLayers[ aCount++ ] = LAYER_SELECTION_SHADOWS;
 }
 
 

eeschema/sch_painter.cpp

@@ -749,11 +749,31 @@ void SCH_PAINTER::draw( const LIB_SYMBOL* aSymbol, int aLayer, bool aDrawFields,
         drawnSymbol = tmpSymbol.get();
     }
 
+    // The parent must exist on the union of all its children's draw layers.  But that doesn't
+    // mean we want to draw each child on the union.
+    auto childOnLayer =
+            []( const LIB_ITEM& item, int layer )
+            {
+                int layers[512], layers_count;
+                item.ViewGetLayers( layers, layers_count );
+
+                for( int ii = 0; ii < layers_count; ++ii )
+                {
+                    if( layers[ii] == layer )
+                        return true;
+                }
+
+                return false;
+            };
+
     for( const LIB_ITEM& item : drawnSymbol->GetDrawItems() )
     {
         if( !aDrawFields && item.Type() == LIB_FIELD_T )
             continue;
 
+        if( !childOnLayer( item, aLayer ) )
+            continue;
+
         if( aUnit && item.GetUnit() && aUnit != item.GetUnit() )
             continue;
 

eeschema/sch_view.h

@@ -52,7 +52,7 @@ static const int SCH_LAYER_ORDER[] =
     LAYER_BUS_JUNCTION, LAYER_JUNCTION, LAYER_NOCONNECT,
     LAYER_HIERLABEL, LAYER_GLOBLABEL, LAYER_LOCLABEL,
     LAYER_SHEETFILENAME, LAYER_SHEETNAME, LAYER_SHEETLABEL, LAYER_SHEETFIELDS,
-    LAYER_NOTES,
+    LAYER_NOTES, LAYER_PRIVATE_NOTES,
     LAYER_WIRE, LAYER_BUS,
     LAYER_DEVICE,
     LAYER_SHEET,