Mine

/*
 * Smallest program to get the error
 *
 */

#include "wx/wx.h" 

class TestPrintV: public wxApp
{
    virtual bool OnInit();
};

IMPLEMENT_APP(TestPrintV)

bool TestPrintV::OnInit()
{
    wxSetlocale(LC_ALL, "C");
    //taken from http://www.wxwidgets.org/docs/faqcmn.htm#printfstr
    wxString str;
    str.Printf("My string is %s", wxString("whatever").c_str());
    return false;
}