This union hasn't been needed for 5 years, and makes using other headers harder.
/*
** $Id: lapi.h,v 2.2.1.1 2007/12/27 13:02:25 roberto Exp $
** Auxiliary functions from Lua API
** See Copyright Notice in lua.h
*/
#ifndef lapi_h
#define lapi_h
#include "lobject.h"
LUAI_FUNC void luaA_pushobject (lua_State *L, const TValue *o);
#endif