python: Annotate type aliases with TypeAlias.

This is not strictly necessary but it’s clearer and improves mypy’s
error messages.

https://docs.python.org/3/library/typing.html#typing.TypeAlias
https://mypy.readthedocs.io/en/stable/kinds_of_types.html#type-aliases

Signed-off-by: Anders Kaseorg <anders@zulip.com>

analytics/lib/counts.py

@@ -8,6 +8,7 @@ from django.conf import settings
 from django.db import connection, models
 from django.db.models import F
 from psycopg2.sql import SQL, Composable, Identifier, Literal
+from typing_extensions import TypeAlias
 
 from analytics.models import (
     BaseCount,
@@ -346,7 +347,7 @@ def do_drop_single_stat(property: str) -> None:
 
 ## DataCollector-level operations ##
 
-QueryFn = Callable[[Dict[str, Composable]], Composable]
+QueryFn: TypeAlias = Callable[[Dict[str, Composable]], Composable]
 
 
 def do_pull_by_sql_query(

analytics/management/commands/populate_analytics_db.py

@@ -5,6 +5,7 @@ from typing import Any, Dict, List, Mapping, Type, Union
 from django.core.files.uploadedfile import UploadedFile
 from django.core.management.base import BaseCommand
 from django.utils.timezone import now as timezone_now
+from typing_extensions import TypeAlias
 
 from analytics.lib.counts import COUNT_STATS, CountStat, do_drop_all_analytics_tables
 from analytics.lib.fixtures import generate_time_series_data
@@ -147,7 +148,7 @@ class Command(BaseCommand):
         with open(IMAGE_FILE_PATH, "rb") as fp:
             upload_message_attachment_from_request(UploadedFile(fp), shylock, file_size)
 
-        FixtureData = Mapping[Union[str, int, None], List[int]]
+        FixtureData: TypeAlias = Mapping[Union[str, int, None], List[int]]
 
         def insert_fixture_data(
             stat: CountStat,

analytics/views/stats.py

@@ -10,6 +10,7 @@ from django.shortcuts import render
 from django.utils import translation
 from django.utils.timezone import now as timezone_now
 from django.utils.translation import gettext as _
+from typing_extensions import TypeAlias
 
 from analytics.lib.counts import COUNT_STATS, CountStat
 from analytics.lib.time_utils import time_range
@@ -242,7 +243,7 @@ def get_chart_data(
     remote_realm_id: Optional[int] = None,
     server: Optional["RemoteZulipServer"] = None,
 ) -> HttpResponse:
-    TableType = Union[
+    TableType: TypeAlias = Union[
         Type["RemoteInstallationCount"],
         Type[InstallationCount],
         Type["RemoteRealmCount"],

confirmation/models.py

@@ -16,6 +16,7 @@ from django.http import HttpRequest, HttpResponse
 from django.template.response import TemplateResponse
 from django.urls import reverse
 from django.utils.timezone import now as timezone_now
+from typing_extensions import TypeAlias
 
 from confirmation import settings as confirmation_settings
 from zerver.lib.types import UnspecifiedValue
@@ -55,7 +56,7 @@ def generate_key() -> str:
     return b32encode(secrets.token_bytes(15)).decode().lower()
 
 
-ConfirmationObjT = Union[
+ConfirmationObjT: TypeAlias = Union[
     MultiuseInvite,
     PreregistrationRealm,
     PreregistrationUser,

zerver/actions/streams.py

@@ -11,6 +11,7 @@ from django.utils.timezone import now as timezone_now
 from django.utils.translation import gettext as _
 from django.utils.translation import override as override_language
 from django_stubs_ext import ValuesQuerySet
+from typing_extensions import TypeAlias
 
 from zerver.actions.default_streams import (
     do_remove_default_stream,
@@ -560,7 +561,7 @@ def send_peer_subscriber_events(
             send_event_on_commit(realm, event, peer_user_ids)
 
 
-SubT = Tuple[List[SubInfo], List[SubInfo]]
+SubT: TypeAlias = Tuple[List[SubInfo], List[SubInfo]]
 
 
 def bulk_add_subscriptions(
@@ -729,7 +730,9 @@ def notify_subscriptions_removed(
     send_event(realm, event, [user_profile.id])
 
 
-SubAndRemovedT = Tuple[List[Tuple[UserProfile, Stream]], List[Tuple[UserProfile, Stream]]]
+SubAndRemovedT: TypeAlias = Tuple[
+    List[Tuple[UserProfile, Stream]], List[Tuple[UserProfile, Stream]]
+]
 
 
 def send_subscription_remove_events(

zerver/data_import/gitter.py

@@ -7,6 +7,7 @@ import orjson
 from django.conf import settings
 from django.forms.models import model_to_dict
 from django.utils.timezone import now as timezone_now
+from typing_extensions import TypeAlias
 
 from zerver.data_import.import_util import (
     ZerverFieldsT,
@@ -29,7 +30,7 @@ from zerver.models import Recipient, UserProfile
 from zproject.backends import GitHubAuthBackend
 
 # stubs
-GitterDataT = List[Dict[str, Any]]
+GitterDataT: TypeAlias = List[Dict[str, Any]]
 
 realm_id = 0
 

zerver/data_import/import_util.py

@@ -25,6 +25,7 @@ import orjson
 import requests
 from django.forms.models import model_to_dict
 from django.utils.timezone import now as timezone_now
+from typing_extensions import TypeAlias
 
 from zerver.data_import.sequencer import NEXT_ID
 from zerver.lib.avatar_hash import user_avatar_path_from_ids
@@ -43,7 +44,7 @@ from zerver.models import (
 from zproject.backends import all_implemented_backend_names
 
 # stubs
-ZerverFieldsT = Dict[str, Any]
+ZerverFieldsT: TypeAlias = Dict[str, Any]
 
 
 class SubscriberHandler:

zerver/data_import/slack.py

@@ -16,6 +16,7 @@ import requests
 from django.conf import settings
 from django.forms.models import model_to_dict
 from django.utils.timezone import now as timezone_now
+from typing_extensions import TypeAlias
 
 from zerver.data_import.import_util import (
     ZerverFieldsT,
@@ -56,11 +57,11 @@ from zerver.models import (
     UserProfile,
 )
 
-SlackToZulipUserIDT = Dict[str, int]
-AddedChannelsT = Dict[str, Tuple[str, int]]
-AddedMPIMsT = Dict[str, Tuple[str, int]]
-DMMembersT = Dict[str, Tuple[str, str]]
-SlackToZulipRecipientT = Dict[str, int]
+SlackToZulipUserIDT: TypeAlias = Dict[str, int]
+AddedChannelsT: TypeAlias = Dict[str, Tuple[str, int]]
+AddedMPIMsT: TypeAlias = Dict[str, Tuple[str, int]]
+DMMembersT: TypeAlias = Dict[str, Tuple[str, str]]
+SlackToZulipRecipientT: TypeAlias = Dict[str, int]
 # Generic type for SlackBotEmail class
 SlackBotEmailT = TypeVar("SlackBotEmailT", bound="SlackBotEmail")
 

zerver/data_import/slack_message_conversion.py

@@ -1,10 +1,12 @@
 import re
 from typing import Any, Dict, List, Optional, Tuple
 
+from typing_extensions import TypeAlias
+
 # stubs
-ZerverFieldsT = Dict[str, Any]
-SlackToZulipUserIDT = Dict[str, int]
-AddedChannelsT = Dict[str, Tuple[str, int]]
+ZerverFieldsT: TypeAlias = Dict[str, Any]
+SlackToZulipUserIDT: TypeAlias = Dict[str, int]
+AddedChannelsT: TypeAlias = Dict[str, Tuple[str, int]]
 
 # Slack link can be in the format <http://www.foo.com|www.foo.com> and <http://foo.com/>
 LINK_REGEX = r"""

zerver/lib/db.py

@@ -3,10 +3,11 @@ from typing import Any, Callable, Dict, Iterable, List, Mapping, Sequence, TypeV
 
 from psycopg2.extensions import connection, cursor
 from psycopg2.sql import Composable
+from typing_extensions import TypeAlias
 
 CursorObj = TypeVar("CursorObj", bound=cursor)
-Query = Union[str, bytes, Composable]
-Params = Union[Sequence[object], Mapping[str, object], None]
+Query: TypeAlias = Union[str, bytes, Composable]
+Params: TypeAlias = Union[Sequence[object], Mapping[str, object], None]
 ParamsT = TypeVar("ParamsT")
 
 

zerver/lib/digest.py

@@ -7,6 +7,7 @@ from typing import Any, Collection, Dict, List, Set, Tuple
 from django.conf import settings
 from django.db import transaction
 from django.utils.timezone import now as timezone_now
+from typing_extensions import TypeAlias
 
 from confirmation.models import one_click_unsubscribe_link
 from zerver.context_processors import common_context
@@ -34,7 +35,7 @@ log_to_file(logger, settings.DIGEST_LOG_PATH)
 DIGEST_CUTOFF = 5
 MAX_HOT_TOPICS_TO_BE_INCLUDED_IN_DIGEST = 4
 
-TopicKey = Tuple[int, str]
+TopicKey: TypeAlias = Tuple[int, str]
 
 
 class DigestTopic:

zerver/lib/export.py

@@ -24,6 +24,7 @@ from django.db.models import Exists, OuterRef, Q
 from django.forms.models import model_to_dict
 from django.utils.timezone import is_naive as timezone_is_naive
 from mypy_boto3_s3.service_resource import Object
+from typing_extensions import TypeAlias
 
 import zerver.lib.upload
 from analytics.models import RealmCount, StreamCount, UserCount
@@ -74,17 +75,17 @@ from zerver.models import (
 )
 
 # Custom mypy types follow:
-Record = Dict[str, Any]
+Record: TypeAlias = Dict[str, Any]
 TableName = str
-TableData = Dict[TableName, List[Record]]
+TableData: TypeAlias = Dict[TableName, List[Record]]
 Field = str
 Path = str
-Context = Dict[str, Any]
-FilterArgs = Dict[str, Any]
-IdSource = Tuple[TableName, Field]
-SourceFilter = Callable[[Record], bool]
+Context: TypeAlias = Dict[str, Any]
+FilterArgs: TypeAlias = Dict[str, Any]
+IdSource: TypeAlias = Tuple[TableName, Field]
+SourceFilter: TypeAlias = Callable[[Record], bool]
 
-CustomFetch = Callable[[TableData, Context], None]
+CustomFetch: TypeAlias = Callable[[TableData, Context], None]
 
 
 class MessagePartial(TypedDict):

zerver/lib/integrations.py

@@ -7,6 +7,7 @@ from django.urls import URLResolver, path
 from django.utils.module_loading import import_string
 from django.utils.translation import gettext_lazy
 from django_stubs_ext import StrPromise
+from typing_extensions import TypeAlias
 
 from zerver.lib.storage import static_path
 
@@ -31,7 +32,7 @@ Over time, we expect this registry to grow additional convenience
 features for writing and configuring integrations efficiently.
 """
 
-OptionValidator = Callable[[str, str], Optional[str]]
+OptionValidator: TypeAlias = Callable[[str, str], Optional[str]]
 
 META_CATEGORY: Dict[str, StrPromise] = {
     "meta-integration": gettext_lazy("Integration frameworks"),

zerver/lib/markdown/__init__.py

@@ -47,6 +47,7 @@ from markdown.blockparser import BlockParser
 from markdown.extensions import codehilite, nl2br, sane_lists, tables
 from soupsieve import escape as css_escape
 from tlds import tld_set
+from typing_extensions import TypeAlias
 
 from zerver.lib import mention
 from zerver.lib.cache import cache_with_key
@@ -148,7 +149,7 @@ class DbData:
 version = 1
 
 _T = TypeVar("_T")
-ElementStringNone = Union[Element, Optional[str]]
+ElementStringNone: TypeAlias = Union[Element, Optional[str]]
 
 EMOJI_REGEX = r"(?P<syntax>:[\w\-\+]+:)"
 

zerver/lib/narrow.py

@@ -43,6 +43,7 @@ from sqlalchemy.sql import (
 )
 from sqlalchemy.sql.selectable import SelectBase
 from sqlalchemy.types import ARRAY, Boolean, Integer, Text
+from typing_extensions import TypeAlias
 
 from zerver.lib.addressee import get_user_profiles, get_user_profiles_by_ids
 from zerver.lib.exceptions import ErrorCode, JsonableError
@@ -207,9 +208,9 @@ class BadNarrowOperatorError(JsonableError):
         return _("Invalid narrow operator: {desc}")
 
 
-ConditionTransform = Callable[[ClauseElement], ClauseElement]
+ConditionTransform: TypeAlias = Callable[[ClauseElement], ClauseElement]
 
-OptionalNarrowListT = Optional[List[Dict[str, Any]]]
+OptionalNarrowListT: TypeAlias = Optional[List[Dict[str, Any]]]
 
 # These delimiters will not appear in rendered messages or HTML-escaped topics.
 TS_START = "<ts-match>"

zerver/lib/push_notifications.py

@@ -17,6 +17,7 @@ from django.db.models import F, Q
 from django.utils.timezone import now as timezone_now
 from django.utils.translation import gettext as _
 from django.utils.translation import override as override_language
+from typing_extensions import TypeAlias
 
 from zerver.lib.avatar import absolute_avatar_url
 from zerver.lib.exceptions import JsonableError
@@ -47,7 +48,7 @@ logger = logging.getLogger(__name__)
 if settings.ZILENCER_ENABLED:
     from zilencer.models import RemotePushDeviceToken, RemoteZulipServer
 
-DeviceToken = Union[PushDeviceToken, "RemotePushDeviceToken"]
+DeviceToken: TypeAlias = Union[PushDeviceToken, "RemotePushDeviceToken"]
 
 
 # We store the token as b64, but apns-client wants hex strings

zerver/lib/queue.py

@@ -17,12 +17,13 @@ from pika.adapters.blocking_connection import BlockingChannel
 from pika.channel import Channel
 from pika.spec import Basic
 from tornado import ioloop
+from typing_extensions import TypeAlias
 
 from zerver.lib.utils import assert_is_not_none
 
 MAX_REQUEST_RETRIES = 3
 ChannelT = TypeVar("ChannelT", Channel, BlockingChannel)
-Consumer = Callable[[ChannelT, Basic.Deliver, pika.BasicProperties, bytes], None]
+Consumer: TypeAlias = Callable[[ChannelT, Basic.Deliver, pika.BasicProperties, bytes], None]
 
 
 # This simple queuing library doesn't expose much of the power of

zerver/lib/test_runner.py

@@ -14,6 +14,7 @@ from django.db import ProgrammingError, connections
 from django.test import runner as django_runner
 from django.test.runner import DiscoverRunner
 from django.test.signals import template_rendered
+from typing_extensions import TypeAlias
 
 from scripts.lib.zulip_tools import (
     TEMPLATE_DATABASE_DIR,
@@ -103,8 +104,8 @@ def process_instrumented_calls(func: Callable[[Dict[str, Any]], None]) -> None:
         func(call)
 
 
-SerializedSubsuite = Tuple[Type[TestSuite], List[str]]
-SubsuiteArgs = Tuple[Type["RemoteTestRunner"], int, SerializedSubsuite, bool, bool]
+SerializedSubsuite: TypeAlias = Tuple[Type[TestSuite], List[str]]
+SubsuiteArgs: TypeAlias = Tuple[Type["RemoteTestRunner"], int, SerializedSubsuite, bool, bool]
 
 
 def run_subsuite(args: SubsuiteArgs) -> Tuple[int, Any]:

zerver/lib/types.py

@@ -3,17 +3,17 @@ from dataclasses import dataclass
 from typing import Any, Callable, Dict, List, Optional, Tuple, TypedDict, TypeVar, Union
 
 from django_stubs_ext import StrPromise
-from typing_extensions import NotRequired
+from typing_extensions import NotRequired, TypeAlias
 
 # See zerver/lib/validator.py for more details of Validators,
 # including many examples
 ResultT = TypeVar("ResultT")
-Validator = Callable[[str, object], ResultT]
-ExtendedValidator = Callable[[str, str, object], str]
-RealmUserValidator = Callable[[int, object, bool], List[int]]
+Validator: TypeAlias = Callable[[str, object], ResultT]
+ExtendedValidator: TypeAlias = Callable[[str, str, object], str]
+RealmUserValidator: TypeAlias = Callable[[int, object, bool], List[int]]
 
 
-ProfileDataElementValue = Union[str, List[int]]
+ProfileDataElementValue: TypeAlias = Union[str, List[int]]
 
 
 class ProfileDataElementBase(TypedDict, total=False):
@@ -36,13 +36,17 @@ class ProfileDataElementUpdateDict(TypedDict):
     value: ProfileDataElementValue
 
 
-ProfileData = List[ProfileDataElement]
+ProfileData: TypeAlias = List[ProfileDataElement]
 
-FieldElement = Tuple[int, StrPromise, Validator[ProfileDataElementValue], Callable[[Any], Any], str]
-ExtendedFieldElement = Tuple[int, StrPromise, ExtendedValidator, Callable[[Any], Any], str]
-UserFieldElement = Tuple[int, StrPromise, RealmUserValidator, Callable[[Any], Any], str]
+FieldElement: TypeAlias = Tuple[
+    int, StrPromise, Validator[ProfileDataElementValue], Callable[[Any], Any], str
+]
+ExtendedFieldElement: TypeAlias = Tuple[
+    int, StrPromise, ExtendedValidator, Callable[[Any], Any], str
+]
+UserFieldElement: TypeAlias = Tuple[int, StrPromise, RealmUserValidator, Callable[[Any], Any], str]
 
-ProfileFieldData = Dict[str, Union[Dict[str, str], str]]
+ProfileFieldData: TypeAlias = Dict[str, Union[Dict[str, str], str]]
 
 
 class UserDisplayRecipient(TypedDict):
@@ -52,7 +56,7 @@ class UserDisplayRecipient(TypedDict):
     is_mirror_dummy: bool
 
 
-DisplayRecipientT = Union[str, List[UserDisplayRecipient]]
+DisplayRecipientT: TypeAlias = Union[str, List[UserDisplayRecipient]]
 
 
 class LinkifierDict(TypedDict):

zerver/tests/test_queue_worker.py

@@ -15,6 +15,7 @@ import time_machine
 from django.conf import settings
 from django.db.utils import IntegrityError
 from django.test import override_settings
+from typing_extensions import TypeAlias
 
 from zerver.lib.email_mirror import RateLimitedRealmMirror
 from zerver.lib.email_mirror_helpers import encode_email_address
@@ -43,7 +44,7 @@ from zerver.worker.queue_processors import (
     get_active_worker_queues,
 )
 
-Event = Dict[str, Any]
+Event: TypeAlias = Dict[str, Any]
 
 
 class FakeClient:

zerver/views/auth.py

@@ -27,7 +27,7 @@ from django.views.decorators.http import require_safe
 from social_django.utils import load_backend, load_strategy
 from two_factor.forms import BackupTokenForm
 from two_factor.views import LoginView as BaseTwoFactorLoginView
-from typing_extensions import Concatenate, ParamSpec
+from typing_extensions import Concatenate, ParamSpec, TypeAlias
 
 from confirmation.models import (
     Confirmation,
@@ -103,7 +103,7 @@ if TYPE_CHECKING:
     from django.http.request import _ImmutableQueryDict
 
 ParamT = ParamSpec("ParamT")
-ExtraContext = Optional[Dict[str, Any]]
+ExtraContext: TypeAlias = Optional[Dict[str, Any]]
 
 EXPIRABLE_SESSION_VAR_DEFAULT_EXPIRY_SECS = 3600
 

zerver/views/events_register.py

@@ -4,6 +4,7 @@ from django.conf import settings
 from django.contrib.auth.models import AnonymousUser
 from django.http import HttpRequest, HttpResponse
 from django.utils.translation import gettext as _
+from typing_extensions import TypeAlias
 
 from zerver.context_processors import get_valid_realm_from_request
 from zerver.lib.compatibility import is_pronouns_field_type_supported
@@ -34,7 +35,7 @@ def _default_narrow(
     return narrow
 
 
-NarrowT = Sequence[Sequence[str]]
+NarrowT: TypeAlias = Sequence[Sequence[str]]
 
 
 @has_request_variables

zerver/webhooks/pagerduty/view.py

@@ -2,6 +2,7 @@ from email.headerregistry import Address
 from typing import Dict, Union
 
 from django.http import HttpRequest, HttpResponse
+from typing_extensions import TypeAlias
 
 from zerver.decorator import webhook_view
 from zerver.lib.exceptions import UnsupportedWebhookEventTypeError
@@ -11,7 +12,7 @@ from zerver.lib.validator import WildValue, check_int, check_none_or, check_stri
 from zerver.lib.webhooks.common import check_send_webhook_message
 from zerver.models import UserProfile
 
-FormatDictType = Dict[str, Union[str, int]]
+FormatDictType: TypeAlias = Dict[str, Union[str, int]]
 
 PAGER_DUTY_EVENT_NAMES = {
     "incident.trigger": "triggered",

zerver/webhooks/taiga/view.py

@@ -9,6 +9,7 @@ should be in bold.
 from typing import Dict, List, Optional, Tuple, Union
 
 from django.http import HttpRequest, HttpResponse
+from typing_extensions import TypeAlias
 
 from zerver.decorator import webhook_view
 from zerver.lib.request import REQ, has_request_variables
@@ -17,8 +18,8 @@ from zerver.lib.validator import WildValue, check_bool, check_none_or, check_str
 from zerver.lib.webhooks.common import check_send_webhook_message
 from zerver.models import UserProfile
 
-EventType = Dict[str, Union[str, Dict[str, Optional[Union[str, bool]]]]]
-ReturnType = Tuple[WildValue, WildValue]
+EventType: TypeAlias = Dict[str, Union[str, Dict[str, Optional[Union[str, bool]]]]]
+ReturnType: TypeAlias = Tuple[WildValue, WildValue]
 
 
 @webhook_view("Taiga")