Fix update of chains of bounded type parameters

Author: theosotr

src/ir/type_utils.py

@@ -522,13 +522,12 @@ def update_type_var_bound_rec(t_param: tp.TypeParameter,
         return
     try:
         current_t = type_var_map[bound]
-        if t.is_subtype(current_t):
-            # The current assignment for the type variable corresponding to
-            # the upper bound of 't_param' is supertype of 't'. So we don't
-            # have to update anything.
-            return
-        t_args[indexes[bound]] = t
-        type_var_map[bound] = t
+        if not t.is_subtype(current_t):
+            t_args[indexes[bound]] = t
+            type_var_map[bound] = t
+        # The current assignment for the type variable corresponding to
+        # the upper bound of 't_param' is supertype of 't'. So we don't
+        # have to update anything.
     except KeyError:
         # This KeyError happens only if a given type parameter has bound
         # corresponding to a type variable of a type constructor. In this

tests/test_type_utils.py

@@ -1062,6 +1062,24 @@ def test_instantiate_type_constructor_with_type_var_map():
         type_param3: type_var
     }
 
+    # Case 4: T1, T2 : T1, T3: T2 (type map = {T3: String})
+    type_param1 = tp.TypeParameter("T1")
+    type_param2 = tp.TypeParameter("T2", bound=type_param1)
+    type_param3 = tp.TypeParameter("T3", bound=type_param2)
+    type_map = {type_param3: kt.String}
+    types = [kt.Number]
+    t_con = tp.TypeConstructor("Con", [type_param1, type_param2, type_param3])
+    ptype, params = tutils.instantiate_type_constructor(
+        t_con, types=types, type_var_map=type_map)
+    assert ptype.type_args == [kt.String,
+                               kt.String,
+                               kt.String]
+    assert params == {
+        type_param1: kt.String,
+        type_param2: kt.String,
+        type_param3: kt.String
+    }
+
 
 def test_unify_types():
     factory = kt.KotlinBuiltinFactory()