Ticket #36880: checks.diff

django/contrib/auth/checks.py

@@ -2 +2 @@
 
 from django.apps import apps
 from django.conf import settings
+from django.contrib.postgres.constraints import ExclusionConstraint
 from django.core import checks
 from django.utils.module_loading import import_string
 
@@ -71 +72 @@
     if not cls._meta.get_field(cls.USERNAME_FIELD).unique and not any(
         constraint.fields == (cls.USERNAME_FIELD,)
         for constraint in cls._meta.total_unique_constraints
+    ) and not any(
+        isinstance(constraint, ExclusionConstraint)
+        and constraint.index_type.lower() == 'hash'
+        and constraint.expressions[0][0] == cls.USERNAME_FIELD
+        for constraint in cls._meta.constraints
     ):
         if settings.AUTHENTICATION_BACKENDS == [
             "django.contrib.auth.backends.ModelBackend"