anchor.diff:  handle_file_error(File, {beam_validator, Rest}) ->
     elixir_errors:form_error([{line, 0}], File, beam_validator, Rest);
   handle_file_error(File, {Line, Module, Desc}) ->
  -  Message = format_error(Module, Desc),
  +  Message = custom_format(Module, Desc),
     elixir_errors:compile_error([{line, Line}], File, Message).
   
  -%% Custom formatting
  -
   %% Mention the capture operator in make_fun
  -format_error(sys_core_fold, {no_effect, {erlang, make_fun, 3}}) ->
  +custom_format(sys_core_fold, {no_effect, {erlang, make_fun, 3}}) ->
     "the result of the capture operator & (:erlang.make_fun/3) is never used";
   
   %% Make no_effect clauses pretty
  -format_error(sys_core_fold, {no_effect, {erlang, F, A}}) ->
  +custom_format(sys_core_fold, {no_effect, {erlang, F, A}}) ->
     {Fmt, Args} = case erl_internal:comp_op(F, A) of
       true -> {"use of operator ~ts has no effect", [elixir_utils:erlang_comparison_op_to_elixir(F)]};
       false ->
  
positive.code: handle_file_warning(_, _File, {_Line, erl_lint, _}) -> ok;
  
  handle_file_warning(_, File, {Line, Module, Desc}) ->
    Message = format_error(Module, Desc),
    elixir_errors:warn(Line, File, Message).
  
  %% Handle warnings
  
negative.code:       format_warnings(Opts, CoreWarnings),
  
        case Fun(CoreForms, [?NO_SPAWN_COMPILER_PROCESS, from_core, no_auto_import, return, {source, Source} | Opts]) of
          {ok, Module, Binary, Warnings} when is_binary(Binary) ->
            format_warnings(Opts, Warnings),
            {Module, Binary};
  
          {ok, Module, _Binary, _Warnings} ->
            elixir_errors:form_error([], File, ?MODULE, {invalid_compilation, Module});
  
          {error, Errors, Warnings} ->
            format_warnings(Opts, Warnings),
  