Fixed #20244: PermissionsMixin now defines a related_query_name for M2Ms

django/contrib/auth/models.py

@@ -295,10 +295,12 @@ class PermissionsMixin(models.Model):
     groups = models.ManyToManyField(Group, verbose_name=_('groups'),
         blank=True, help_text=_('The groups this user belongs to. A user will '
                                 'get all permissions granted to each of '
-                                'his/her group.'))
+                                'his/her group.'),
+        related_name="user_set", related_query_name="user")
     user_permissions = models.ManyToManyField(Permission,
         verbose_name=_('user permissions'), blank=True,
-        help_text='Specific permissions for this user.')
+        help_text='Specific permissions for this user.',
+        related_name="user_set", related_query_name="user")
 
     class Meta:
         abstract = True

django/contrib/auth/tests/test_custom_user.py

@@ -4,7 +4,9 @@ from django.contrib.auth.models import (
     AbstractBaseUser,
     AbstractUser,
     UserManager,
-    PermissionsMixin
+    PermissionsMixin,
+    Group,
+    Permission,
 )
 
 
@@ -81,6 +83,20 @@ class CustomUser(AbstractBaseUser):
         return self.is_admin
 
 
+# At this point, temporarily remove the groups and user_permissions M2M
+# fields from the AbstractUser class, so they don't clash with the related_name
+# that sets.
+
+old_au_local_m2m = AbstractUser._meta.local_many_to_many
+old_pm_local_m2m = PermissionsMixin._meta.local_many_to_many
+groups = models.ManyToManyField(Group, blank=True)
+groups.contribute_to_class(PermissionsMixin, "groups")
+user_permissions = models.ManyToManyField(Permission, blank=True)
+user_permissions.contribute_to_class(PermissionsMixin, "user_permissions")
+PermissionsMixin._meta.local_many_to_many = [groups, user_permissions]
+AbstractUser._meta.local_many_to_many = [groups, user_permissions]
+
+
 # The extension user is a simple extension of the built-in user class,
 # adding a required date_of_birth field. This allows us to check for
 # any hard references to the name "User" in forms/handlers etc.
@@ -178,3 +194,7 @@ class CustomUserBadRequiredFields(AbstractBaseUser):
 
     class Meta:
         app_label = 'auth'
+
+# Undo swap hack
+AbstractUser._meta.local_many_to_many = old_au_local_m2m
+PermissionsMixin._meta.local_many_to_many = old_pm_local_m2m