check for self assignment in operator=

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@56794 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/filename.h

@@ -175,7 +175,7 @@ public:
         // assorted assignment operators
 
     wxFileName& operator=(const wxFileName& filename)
-        { Assign(filename); return *this; }
+        { if (this != &filename) Assign(filename); return *this; }
 
     wxFileName& operator=(const wxString& filename)
         { Assign(filename); return *this; }