Fixed #33805 -- Made admin's many-to-many widgets do not display help text for selecting values when allow_multiple_selected is False.

django/contrib/admin/options.py

@@ -314,8 +314,12 @@ class BaseModelAdmin(metaclass=forms.MediaDefiningClass):
                 kwargs["queryset"] = queryset
 
         form_field = db_field.formfield(**kwargs)
-        if isinstance(form_field.widget, SelectMultiple) and not isinstance(
-            form_field.widget, (CheckboxSelectMultiple, AutocompleteSelectMultiple)
+        if (
+            isinstance(form_field.widget, SelectMultiple)
+            and form_field.widget.allow_multiple_selected
+            and not isinstance(
+                form_field.widget, (CheckboxSelectMultiple, AutocompleteSelectMultiple)
+            )
         ):
             msg = _(
                 "Hold down “Control”, or “Command” on a Mac, to select more than one."

tests/admin_widgets/tests.py

@@ -273,6 +273,26 @@ class AdminFormfieldForDBFieldTests(SimpleTestCase):
             "Hold down “Control”, or “Command” on a Mac, to select more than one.",
         )
 
+    def test_m2m_widgets_no_allow_multiple_selected(self):
+        class NoAllowMultipleSelectedWidget(forms.SelectMultiple):
+            allow_multiple_selected = False
+
+        class AdvisorAdmin(admin.ModelAdmin):
+            filter_vertical = ["companies"]
+            formfield_overrides = {
+                ManyToManyField: {"widget": NoAllowMultipleSelectedWidget},
+            }
+
+        self.assertFormfield(
+            Advisor,
+            "companies",
+            widgets.FilteredSelectMultiple,
+            filter_vertical=["companies"],
+        )
+        ma = AdvisorAdmin(Advisor, admin.site)
+        f = ma.formfield_for_dbfield(Advisor._meta.get_field("companies"), request=None)
+        self.assertEqual(f.help_text, "")
+
 
 @override_settings(ROOT_URLCONF="admin_widgets.urls")
 class AdminFormfieldForDBFieldWithRequestTests(TestDataMixin, TestCase):