codomain done based on tlv

[TESTS][LAMBDA] Add a test on comp of sigmas

tests/lambda/src/lambdaTests.ml

@@ -491,6 +491,12 @@ let tests_eval = "CDuce runtime tests (Typed -> Lambda -> Value)" >:::
  } })))"
 	(run_test_eval "(((fun f x : 'A : 'A -> x)[{A/Int}])[{A/String}])[{A/Int}]");
 
+      assert_equal ~msg:"Test CDuce.runtime.poly.multicomp.2 failed"
+	~printer:(fun x -> x) "Abstraction((`$A,`$A),Sel(1,(`$A -> `$A),Comp(Comp({ { `$A = `$B
+ } },{ { `$B = `$A } }),{ { `$A = `$B
+ } })))"
+	(run_test_eval "(((fun f x : 'A : 'A -> x)[{A/'B}])[{B/'A}])[{A/'B}]");
+
     );
 
   ]

types/types.ml

@@ -3240,8 +3240,8 @@ module Tallying = struct
 
   let codomain ll =
     List.fold_left (fun acc e ->
-      CS.E.fold (fun v _ acc ->
-        Var.Set.add v acc
+      CS.E.fold (fun _ v acc ->
+        Var.Set.union v.toplvars.TLV.fv acc
       ) e acc
     ) Var.Set.empty ll