Remove deleted item global variables

Fixes https://gitlab.com/kicad/code/kicad/issues/4819

eeschema/sch_sheet_path.cpp

@@ -63,6 +63,16 @@ public:
         return wxT( "DELETED_SHEET_ITEM" );
     }
 
+    static DELETED_SHEET_ITEM* GetInstance()
+    {
+        static DELETED_SHEET_ITEM* item = nullptr;
+
+        if( !item )
+            item = new DELETED_SHEET_ITEM();
+
+        return item;
+    }
+
     // pure virtuals:
     void SetPosition( const wxPoint& ) override {}
     void Print( RENDER_SETTINGS* aSettings, const wxPoint&  aOffset ) override {}
@@ -76,8 +86,6 @@ public:
 #endif
 };
 
-DELETED_SHEET_ITEM* g_DeletedItem = nullptr;
-
 
 namespace std
 {
@@ -530,10 +538,7 @@ SCH_ITEM* SCH_SHEET_LIST::GetItem( const KIID& aID, SCH_SHEET_PATH* aPathOut )
     }
 
     // Not found; weak reference has been deleted.
-    if( !g_DeletedItem )
-        g_DeletedItem = new DELETED_SHEET_ITEM();
-
-    return g_DeletedItem;
+    return DELETED_SHEET_ITEM::GetInstance();
 }
 
 

pcbnew/class_board.cpp

@@ -76,6 +76,15 @@ public:
         return wxPoint(0, 0);
     }
 
+    static DELETED_BOARD_ITEM* GetInstance()
+    {
+        static DELETED_BOARD_ITEM* item = nullptr;
+
+        if( !item )
+            item = new DELETED_BOARD_ITEM();
+
+        return item;
+    }
 
 #if defined(DEBUG)
     void Show( int , std::ostream&  ) const override {}
@@ -807,10 +816,7 @@ BOARD_ITEM* BOARD::GetItem( const KIID& aID )
         return this;
 
     // Not found; weak reference has been deleted.
-    if( !g_DeletedItem )
-        g_DeletedItem = new DELETED_BOARD_ITEM();
-
-    return g_DeletedItem;
+    return DELETED_BOARD_ITEM::GetInstance();
 }