[FIX] core: don't send readonly fields in o2m in SSF

The SSF would correctly filter out readonly fields when saving a
toplevel form, however it could not remove readonly values when saving
o2m pseudo-records to the parent form (as these would be expected to
remain available for reading upon the next edition and whatnot), so
these values would get sent in 0/1 commands.

Filter out these fields during the parent / toplevel save call.

Complexity notes:

* evaluating readonly modifiers requires the entire record, so
  unchanged fields still have to be written back to the parent form
  and be filtered out when *it* is set up for save, an alternative
  would be to store the `changed` and `readonly` flags alongside the
  record dict, and have the post-process only override the
  pre-computed readonly flag using force_save
* had to fix a test to match the new behaviour, the post-edition
  states turns out to be in line with the client's behaviour (or how
  it looks anyway)

Fixes #32019

3 files changed, 42 insertions, 2 deletions

diff --git a/odoo/addons/test_testing_utilities/ir.model.access.csv b/odoo/addons/test_testing_utilities/ir.model.access.csv
index be5208234d3..c43b736c531 100644
--- a/odoo/addons/test_testing_utilities/ir.model.access.csv
+++ b/odoo/addons/test_testing_utilities/ir.model.access.csv
@@ -17,3 +17,5 @@ access_test_testing_utilities_onchange_parent,access_test_testing_utilities_onch
 access_test_testing_utilities_onchange_line,access_test_testing_utilities_onchange_line,model_test_testing_utilities_onchange_line,,1,0,0,0
 access_model_test_testing_utilities_onchange_count,access_model_test_testing_utilities_onchange_count,model_test_testing_utilities_onchange_count,,1,1,1,1
 access_test_testing_utilities_onchange_count_sub,access_test_testing_utilities_onchange_count_sub,model_test_testing_utilities_onchange_count_sub,,1,1,1,1
+access_o2m_readonly_subfield_parent,access_o2m_readonly_subfield_parent,model_o2m_readonly_subfield_parent,,1,1,1,1
+access_o2m_readonly_subfield_child,access_o2m_readonly_subfield_child,model_o2m_readonly_subfield_child,,1,1,1,1
diff --git a/odoo/addons/test_testing_utilities/models.py b/odoo/addons/test_testing_utilities/models.py
index 96b6364b45e..0c04bc06e8d 100644
--- a/odoo/addons/test_testing_utilities/models.py
+++ b/odoo/addons/test_testing_utilities/models.py
@@ -240,3 +240,24 @@ class O2MChangeSub(models.Model):
 
     parent = fields.Many2one('test_testing_utilities.onchange_count')
     name = fields.Char()
+
+class O2MReadonlySubfield(models.Model):
+    _name = 'o2m_readonly_subfield_parent'
+    _description = _name
+
+    line_ids = fields.One2many('o2m_readonly_subfield_child', 'parent_id')
+
+class O2MReadonlySubfieldChild(models.Model):
+    _name = _description = 'o2m_readonly_subfield_child'
+
+    name = fields.Char()
+    parent_id = fields.Many2one('o2m_readonly_subfield_parent')
+    f = fields.Integer(compute='_compute_f', inverse='_inverse_f', readonly=True)
+
+    @api.depends('name')
+    def _compute_f(self):
+        for r in self:
+            r.f = len(r.name) if r.name else 0
+
+    def _inverse_f(self):
+        raise AssertionError("Inverse of f should not be called")
diff --git a/odoo/addons/test_testing_utilities/tests/test_form_impl.py b/odoo/addons/test_testing_utilities/tests/test_form_impl.py
index 6b18fb229df..0191a4da7ad 100644
--- a/odoo/addons/test_testing_utilities/tests/test_form_impl.py
+++ b/odoo/addons/test_testing_utilities/tests/test_form_impl.py
@@ -359,7 +359,7 @@ class TestO2M(TransactionCase):
 
         self.assertEqual(
             [get(s) for s in r.subs],
-            [("5", 2, 5)]
+            [("5", 0, 5)]
         )
 
     def test_o2m_inner_default(self):
@@ -409,7 +409,10 @@ class TestO2M(TransactionCase):
             self.assertEqual(sub.value, 1)
             self.assertEqual(sub.v, 1)
 
-    def test_m2o_readonly(self):
+    def test_readonly_o2m(self):
+        """ Tests that o2m fields flagged as readonly (readonly="1" in the
+        view) can't be written to
+        """
         r = self.env['test_testing_utilities.parent'].create({
             'subs': [(0, 0, {})]
         })
@@ -422,6 +425,20 @@ class TestO2M(TransactionCase):
         with self.assertRaises(AssertionError):
             f.subs.remove(index=0)
 
+    def test_o2m_readonly_subfield(self):
+        """ Tests that readonly is applied to the field of the o2m = not sent
+        as part of the create / write values
+        """
+        f = Form(self.env['o2m_readonly_subfield_parent'])
+        with f.line_ids.new() as new_line:
+            new_line.name = "ok"
+            self.assertEqual(new_line.f, 2)
+        r = f.save()
+        self.assertEqual(
+            (r.line_ids.name, r.line_ids.f),
+            ('ok', 2)
+        )
+
     def test_o2m_dyn_onchange(self):
         f = Form(self.env['test_testing_utilities.onchange_parent'], view='test_testing_utilities.m2o_onchange_view')