static O[] massageArgsForVarArgsCall(Executable m, O[] args) {
  Class<?>[] types = m.getParameterTypes();
  int n = types.length-1, nArgs = l(args);
  if (nArgs < n) null;
  for i to n:
    if (!argumentCompatibleWithType(args[i], types[i]))
      null;
  Class varArgType = types[n].getComponentType();
  for (int i = n; i < nArgs; i++)
    if (!argumentCompatibleWithType(args[i], varArgType))
      null;
  O[] newArgs = new O[n+1];
  arraycopy(args, 0, newArgs, 0, n);
  
  // TODO: optimize
  
  int nVarArgs = nArgs-n;
  O varArgs = Array.newInstance(varArgType, nVarArgs);
  for i to nVarArgs:
    Array.set(varArgs, i, args[n+i]);
    
  newArgs[n] = varArgs;
  ret newArgs;
}