anchor.diff:  %% vanilla erlang compiler 'compile'.
   
   do_ok_return(#comp{lfile=Lfile,opts=Opts,ret=Ret0,warnings=Ws}=St) ->
  -    case werr(St) of
  +    case werror(St) of
   	true -> do_error_return(St);		%Warnings are errors!
   	false ->
   	    when_opt(report, Opts, fun () -> list_warnings(Lfile, Ws) end),
  
positive.code: 	       (_) -> true			%Everything else
  	   end, [return|Os]).			%Ensure return!
  
  werr(#comp{opts=Opts,warnings=Ws}) ->
      member(warnings_as_errors, Opts) andalso length(Ws) > 0.
  
  %% do_ok_return(State) -> {ok,Mod,...}.
  
negative.code:      {when_flag,to_core,{done,fun core_pp/2,"core"}},
       {when_flag,to_kernel,{done,fun kernel_pp/2,"kernel"}},
       {when_flag,to_asm,{done,fun asm_pp/2,"S"}},
       {unless_test,fun werror/1,{done,fun beam_write/2,"beam"}}]. %Should be last
  
  do_passes([{do,Fun}|Ps], St0) ->
      case Fun(St0) of
  