datetime.tzinfo is abstract (#8908)

stdlib/datetime.pyi

@@ -1,5 +1,6 @@
 import sys
 from _typeshed import Self
+from abc import ABCMeta, abstractmethod
 from time import struct_time
 from typing import ClassVar, NamedTuple, NoReturn, SupportsAbs, TypeVar, overload
 from typing_extensions import Literal, TypeAlias, final
@@ -14,9 +15,12 @@ _D = TypeVar("_D", bound=date)
 MINYEAR: Literal[1]
 MAXYEAR: Literal[9999]
 
-class tzinfo:
+class tzinfo(metaclass=ABCMeta):
+    @abstractmethod
     def tzname(self, __dt: datetime | None) -> str | None: ...
+    @abstractmethod
     def utcoffset(self, __dt: datetime | None) -> timedelta | None: ...
+    @abstractmethod
     def dst(self, __dt: datetime | None) -> timedelta | None: ...
     def fromutc(self, __dt: datetime) -> datetime: ...
 
@@ -29,6 +33,9 @@ class timezone(tzinfo):
     min: ClassVar[timezone]
     max: ClassVar[timezone]
     def __init__(self, offset: timedelta, name: str = ...) -> None: ...
+    def tzname(self, __dt: datetime | None) -> str: ...
+    def utcoffset(self, __dt: datetime | None) -> timedelta: ...
+    def dst(self, __dt: datetime | None) -> None: ...
 
 if sys.version_info >= (3, 11):
     UTC: timezone

stdlib/zoneinfo/__init__.pyi

@@ -1,6 +1,6 @@
 from _typeshed import Self, StrPath
 from collections.abc import Iterable, Sequence
-from datetime import tzinfo
+from datetime import datetime, timedelta, tzinfo
 from typing import Any, Protocol
 
 __all__ = ["ZoneInfo", "reset_tzpath", "available_timezones", "TZPATH", "ZoneInfoNotFoundError", "InvalidTZPathWarning"]
@@ -19,6 +19,9 @@ class ZoneInfo(tzinfo):
     def from_file(cls: type[Self], __fobj: _IOBytes, key: str | None = ...) -> Self: ...
     @classmethod
     def clear_cache(cls, *, only_keys: Iterable[str] | None = ...) -> None: ...
+    def tzname(self, __dt: datetime | None) -> str | None: ...
+    def utcoffset(self, __dt: datetime | None) -> timedelta | None: ...
+    def dst(self, __dt: datetime | None) -> timedelta | None: ...
 
 # Note: Both here and in clear_cache, the types allow the use of `str` where
 # a sequence of strings is required. This should be remedied if a solution

stubs/python-dateutil/dateutil/tz/_common.pyi

@@ -1,3 +1,4 @@
+import abc
 from datetime import datetime, timedelta, tzinfo
 from typing import ClassVar
 
@@ -8,7 +9,7 @@ class _DatetimeWithFold(datetime):
     @property
     def fold(self): ...
 
-class _tzinfo(tzinfo):
+class _tzinfo(tzinfo, metaclass=abc.ABCMeta):
     def is_ambiguous(self, dt: datetime) -> bool: ...
     def fromutc(self, dt: datetime) -> datetime: ...