[FIX] base: handling of *_view_ref in SSF

The feature was not tested, and as it turns out completely broken:

* the non-raw string means the "backrefs" were really interpreted as
  octal literals
* the second backref was entirely wrong

Also add all loaded views to the field descriptor in case we might
have a use for it (and because inline sub-views are always stored on
the descriptor).

closes odoo/odoo#28194

odoo/addons/test_testing_utilities/tests/test_form_impl.py

@@ -284,6 +284,20 @@ class TestO2M(TransactionCase):
         delegating to a separate form view
         """
         f = Form(self.env['test_testing_utilities.parent'], view='test_testing_utilities.o2m_parent_ed')
+        custom_tree = self.env.ref('test_testing_utilities.editable_external').id
+
+        subs_field = f._view['fields']['subs']
+        tree_view = subs_field['views']['tree']
+        self.assertEqual(tree_view['type'], 'tree')
+        self.assertEqual(
+            tree_view['view_id'], custom_tree,
+            'check that the tree view is the one referenced by tree_view_ref'
+        )
+        self.assertIs(subs_field['views']['edition'], tree_view, "check that the edition view is the tree view")
+        self.assertEqual(
+            subs_field['views']['edition']['view_id'],
+            custom_tree
+        )
 
         with f.subs.new() as s:
             s.value = 1

odoo/tests/common.py

@@ -989,10 +989,10 @@ def can_import(module):
 
 # TODO: sub-views (o2m, m2m) -> sub-form?
 # TODO: domains
-ref_re = re.compile("""
+ref_re = re.compile(r"""
 # first match 'form_view_ref' key, backrefs are used to handle single or
 # double quoting of the value
-(['"])(?P<view_type>\w+)_view_ref\1
+(['"])(?P<view_type>\w+_view_ref)\1
 # colon separator (with optional spaces around)
 \s*:\s*
 # open quote for value
@@ -1003,7 +1003,7 @@ ref_re = re.compile("""
     [.\w]+
 )
 # close with same quote as opening
-\2
+\3
 """, re.VERBOSE)
 class Form(object):
     """ Server-side form view implementation (partial)
@@ -1119,6 +1119,8 @@ class Form(object):
                 .load_views([(False, 'tree'), (False, 'form')])['fields_views']
             # embedded views should take the priority on externals
             views.update(descr['views'])
+            # re-set all resolved views on the descriptor
+            descr['views'] = views
 
             # if the default view is a kanban or a non-editable list, the
             # "edition controller" is the form view