fix: enable getting root cause for extra_validation errors

src/eon_type.erl

@@ -286,7 +286,10 @@ typecheck(#spec{term=Term0, type=Type, p_have=P_have}) ->
         true ->
           case Type:extra_validation(Term, P_have) of
             ok -> Term;
-            {error, Reason} -> {error, {untypable, Reason}}
+            %% Since the extra_validation is typically used for checks
+            %% involving several terms, we return a reason given by
+            %% the validation code instead of a term name.
+            {error, Reason} -> {error, {untypable, [{x, Type, x, Reason, []}]}}
           end;
         false ->
           Term

src/eon_type_error.erl

@@ -79,4 +79,10 @@ get_root_cause__list_type__test() ->
   {error, Rsn} = eon_type:check_term([<<"foo">>, 42], test_strings),
   ?assertEqual({42, test_string}, get_root_cause(Rsn)).
 
+get_root_cause__extra_validation__test() ->
+    {error, Rsn} = eon_type:check_term([{<<"foo">>, 17}], test_rec_extra),
+    ?assertMatch({nope, test_rec_extra}, get_root_cause(Rsn)),
+    {error, Rsn2} = eon_type:check_term([{<<"foo">>, 117}], test_rec_extra),
+    ?assertMatch({117, test_prim}, get_root_cause(Rsn2)).
+
 -endif.

test/test_rec_extra.erl

@@ -0,0 +1,15 @@
+-module(test_rec_extra).
+-behaviour(eon_type_rec).
+-include_lib("stdlib2/include/prelude.hrl").
+-export([name/0, parameters/0, decl/2, extra_validation/2]).
+
+name() -> some_obj.
+
+parameters() -> [].
+
+decl(_Obj, _Params) ->
+    [ <<"foo">>, {test_prim, [min,0, max,100]}
+    ].
+
+extra_validation(_Term, _Params) ->
+    {error, nope}.