[erlang-bugs] Typer Bug ?

[P Arun Babu]

Hi,

typer seems to be producing wrong spec for the below code. 

Also, dialyzer with "-Wunmatched_returns -Werror_handling -Wbehaviours -Wunderspecs -Woverspecs"  shows no warnings.


I am wondering ... is this a bug ?


Thanks,

-ARUN



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%% File: "test.erl"
%% ----------------
-spec is_valid(_) -> boolean().
-spec start(_,_) -> {['abs_n1_minus_n2_gt_5' | 'both_are_invalid' | 
'n1_is_invalid' | 'n2_is_invalid' | 'this_could_be_a_bug'],_,'not_ok' | 
'ok'}.


 -module(test).

-export([start/2]).

is_valid (N) ->
    N > 10.

start ( N1 , N2) ->

    Is_valid_N1 = is_valid (N1),
    Is_valid_N2 = is_valid (N2),

    case {Is_valid_N1, Is_valid_N2} of

        { false, true  }     -> 
                    { [n1_is_invalid], N2 , ok};

        {  true, false }    -> 
                    { [n2_is_invalid], N1, ok};
        { false, false }     -> 
                    { [
                        n1_is_invalid, 
                        n2_is_invalid,
                        both_are_invalid,
                        this_could_be_a_bug
                      ],
                      invalid, not_ok };
        {  true, true  }     -> 
                    case N1 < N2 of
                        true ->  Minimum = N1;
                        false -> Minimum = N2 
                    end,

                    case abs(N1- N2) > 5.0 of
                        false -> {                    [], Minimum, ok }; 
                        true ->  {    [abs_n1_minus_n2_gt_5], Minimum, ok } 
                    end
    end.
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