anchor.diff:      Vs = handle_reuse_annos(Vs0, St0),
       Rs = break_rets(Br),
       {B1,Bu,St1} = umatch(B0, Br, St0),
  -    if St0#kern.guard_refc > 0 ->
  +    case is_in_guard(St1) of
  +	true ->
   	    {#k_guard_match{anno=#k{us=Bu,ns=lit_list_vars(Rs),a=A},
   			    vars=Vs,body=B1,ret=Rs},Bu,St1};
  -       true ->
  +	false ->
   	    {#k_match{anno=#k{us=Bu,ns=lit_list_vars(Rs),a=A},
   		      vars=Vs,body=B1,ret=Rs},Bu,St1}
       end;
  
positive.code:     [N|integers(N + 1, M)];
  integers(_, _) -> [].
  
  %%%
  %%% Handling of errors and warnings.
  %%%
  
negative.code:     {#k_return{anno=#k{us=Au,ns=[],a=A},args=As},Au,St};
  ubody(#ivalues{anno=A,args=As}, {break,_Vbs}, St) ->
      Au = lit_list_vars(As),
      case is_in_guard(St) of
  	true ->
  	    {#k_guard_break{anno=#k{us=Au,ns=[],a=A},args=As},Au,St};
  	false ->
  	    {#k_break{anno=#k{us=Au,ns=[],a=A},args=As},Au,St}
      end;
  ubody(#ivalues{anno=A,args=As}, {guard_break,_Vbs}, St) ->
  