anchor.diff:      #xrefr{funvars = FunVars, matches = Matches} = S,
       clauses(Cls, FunVars, Matches, S).
   
  -clauses([{clause, _Line, _H, G, B} | Cs], FunVars, Matches, S) ->
  +clauses([{clause, _Anno, _H, G, B} | Cs], FunVars, Matches, S) ->
       S1 = case S#xrefr.builtins_too of
   	     true -> expr(G, S);
   	     false -> S
  
positive.code: 	{type, _} ->
  	    expr(ArgsList, S1);
  	{apply2, [{tuple, _, [M,F]}, ArgsTerm]} ->
  	    eval_args(M, F, ArgsTerm, Line, S1, ArgsList, []);
  	{1, [{tuple, _, [M,F]} | R]} ->	% R = [] unless spawn_opt
  	    eval_args(M, F, list2term([]), Line, S1, ArgsList, R);
  	{2, [Node, {tuple, _, [M,F]} | R]} -> % R = [] unless spawn_opt
  	    eval_args(M, F, list2term([]), Line, S1, ArgsList, [Node | R]);
  	{3, [M, F, ArgsTerm | R]} -> % R = [] unless spawn_opt
  	    eval_args(M, F, ArgsTerm, Line, S1, ArgsList, R);
  	{4, [Node, M, F, ArgsTerm | R]} -> % R = [] unless spawn_opt
  	    eval_args(M, F, ArgsTerm, Line, S1, ArgsList, [Node | R]);
  	{debug4, [M, F, ArgsTerm, _]} ->
  	    eval_args(M, F, ArgsTerm, Line, S1, ArgsList, []);
  	_Else -> % apply2, 1 or 2
  	    check_funarg(W, ArgsList, Line, S1)
      end.
  
  eval_args(Mod, Fun, ArgsTerm, Line, S, ArgsList, Extra) ->
      {IsSimpleCall, M, F} = mod_fun(Mod, Fun),
      case term2list(ArgsTerm, [], S) of
  	undefined ->
  	    S1 = unresolved(M, F, -1, Line, S),
  	    expr(ArgsList, S1);
  	ArgsList2 when not IsSimpleCall ->
  	    S1 = unresolved(M, F, length(ArgsList2), Line, S),
  	    expr(ArgsList, S1);
  	ArgsList2 when IsSimpleCall ->
  	    S1 = expr(Extra, S),
  	    external_call(M, F, ArgsList2, Line, false, S1)
      end.
  
  mod_fun({atom,_,M1}, {atom,_,F1}) -> {true, M1, F1};
  
negative.code: term2list(_Else, _L, _S) ->
      undefined.
  
  unresolved(M, F, A, Anno, S) ->
      handle_call(external, {M,F,A}, Anno, S, true).
  
  handle_call(Locality, Module, Name, Arity, Anno, S) ->
      case xref_utils:is_builtin(Module, Name, Arity) of
  	true when not S#xrefr.builtins_too -> S;
  	_Else ->
  	    To = {Module, Name, Arity},
  	    handle_call(Locality, To, Anno, S, false)
      end.
  
  handle_call(Locality, To0, Anno, S, IsUnres) ->
  