Convert element joined domains into domain when searching for OR-ed domain

The content of joined domains can be a single clause, so it must be converted
into a domain before calling search_domain.

Closes #12460

trytond/trytond/model/modelsql.py

@@ -1655,6 +1655,7 @@ class ModelSQL(ModelStorage):
         if joined_domains is not None:
             union_tables = []
             for sub_domain in joined_domains:
+                sub_domain = [sub_domain]  # it may be a clause
                 tables, expression = cls.search_domain(sub_domain)
                 if rule_domain:
                     tables, domain_exp = cls.search_domain(

trytond/trytond/tests/test_modelsql.py

@@ -823,6 +823,26 @@ class ModelSQLTestCase(unittest.TestCase):
         self.assertIn('UNION', str(Model.search(domain, query=True)))
         self.assertNotIn('UNION', str(query_without_split))
 
+    @with_transaction()
+    def test_search_or_to_union_with_in_clause(self):
+        "Test searching for 'OR'-ed domain with in clause"
+        pool = Pool()
+        Model = pool.get('test.modelsql.search.or2union')
+
+        record, = Model.create([{
+                    'name': "Foo",
+                    'targets': [('create', [{
+                                    'name': "Bar",
+                                    }]),
+                        ],
+                    }])
+
+        domain = ['OR',
+            ('name', '=', 'Bar'),
+            ('targets.id', 'in', [t.id for t in record.targets]),
+            ]
+        self.assertEqual(Model.search(domain), [record])
+
     @with_transaction()
     def test_search_or_to_union_order_eager_field(self):
         """