Drop Python 3.8 support in builtins (#13762)

* remove py38 branches in `builtins`

* combined `builtins.dict` tests with those exclusive to `>=3.9`

Author: jorenham

stdlib/@tests/test_cases/builtins/check_dict-py39.py

@@ -1,7 +1,8 @@
 from __future__ import annotations
 
-from typing import Any, Dict, Generic, Iterable, TypeVar, Union
-from typing_extensions import assert_type
+import os
+from typing import Any, Dict, Generic, Iterable, Mapping, TypeVar, Union
+from typing_extensions import Self, assert_type
 
 # These do follow `__init__` overloads order:
 # mypy and pyright have different opinions about this one:
@@ -148,3 +149,61 @@ def test11() -> str:
 
 def test12() -> str:
     return d_str.get("key", int_value)  # type: ignore[arg-type]
+
+
+# Tests for `dict.__(r)or__`.
+
+
+class CustomDictSubclass(dict[_KT, _VT]):
+    pass
+
+
+class CustomMappingWithDunderOr(Mapping[_KT, _VT]):
+    def __or__(self, other: Mapping[_KT, _VT]) -> dict[_KT, _VT]:
+        return {}
+
+    def __ror__(self, other: Mapping[_KT, _VT]) -> dict[_KT, _VT]:
+        return {}
+
+    def __ior__(self, other: Mapping[_KT, _VT]) -> Self:
+        return self
+
+
+def test_dict_dot_or(
+    a: dict[int, int],
+    b: CustomDictSubclass[int, int],
+    c: dict[str, str],
+    d: Mapping[int, int],
+    e: CustomMappingWithDunderOr[str, str],
+) -> None:
+    # dict.__(r)or__ always returns a dict, even if called on a subclass of dict:
+    assert_type(a | b, dict[int, int])
+    assert_type(b | a, dict[int, int])
+
+    assert_type(a | c, dict[Union[int, str], Union[int, str]])
+
+    # arbitrary mappings are not accepted by `dict.__or__`;
+    # it has to be a subclass of `dict`
+    a | d  # type: ignore
+
+    # but Mappings such as `os._Environ` or `CustomMappingWithDunderOr`,
+    # which define `__ror__` methods that accept `dict`, are fine:
+    assert_type(a | os.environ, dict[Union[str, int], Union[str, int]])
+    assert_type(os.environ | a, dict[Union[str, int], Union[str, int]])
+
+    assert_type(c | os.environ, dict[str, str])
+    assert_type(c | e, dict[str, str])
+
+    assert_type(os.environ | c, dict[str, str])
+    assert_type(e | c, dict[str, str])
+
+    # store "untainted" `CustomMappingWithDunderOr[str, str]` to test `__ior__` against ` dict[str, str]` later
+    # Invalid `e |= a` causes pyright to join `Unknown` to `e`'s type
+    f = e
+
+    e |= c
+    e |= a  # type: ignore
+
+    c |= f
+
+    c |= a  # type: ignore

stdlib/@tests/test_cases/builtins/check_dict.py

@@ -32,7 +32,7 @@ from _typeshed import (
 )
 from collections.abc import Awaitable, Callable, Iterable, Iterator, MutableSet, Reversible, Set as AbstractSet, Sized
 from io import BufferedRandom, BufferedReader, BufferedWriter, FileIO, TextIOWrapper
-from types import CellType, CodeType, TracebackType
+from types import CellType, CodeType, GenericAlias, TracebackType
 
 # mypy crashes if any of {ByteString, Sequence, MutableSequence, Mapping, MutableMapping}
 # are imported from collections.abc in builtins.pyi
@@ -72,9 +72,6 @@ from typing_extensions import (  # noqa: Y023
     deprecated,
 )
 
-if sys.version_info >= (3, 9):
-    from types import GenericAlias
-
 _T = TypeVar("_T")
 _I = TypeVar("_I", default=int)
 _T_co = TypeVar("_T_co", covariant=True)
@@ -377,10 +374,8 @@ class float:
     def __rpow__(self, value: float, mod: None = None, /) -> Any: ...
     def __getnewargs__(self) -> tuple[float]: ...
     def __trunc__(self) -> int: ...
-    if sys.version_info >= (3, 9):
-        def __ceil__(self) -> int: ...
-        def __floor__(self) -> int: ...
-
+    def __ceil__(self) -> int: ...
+    def __floor__(self) -> int: ...
     @overload
     def __round__(self, ndigits: None = None, /) -> int: ...
     @overload
@@ -519,16 +514,15 @@ class str(Sequence[str]):
         ) -> LiteralString: ...
         @overload
         def replace(self, old: str, new: str, count: SupportsIndex = -1, /) -> str: ...  # type: ignore[misc]
-    if sys.version_info >= (3, 9):
-        @overload
-        def removeprefix(self: LiteralString, prefix: LiteralString, /) -> LiteralString: ...
-        @overload
-        def removeprefix(self, prefix: str, /) -> str: ...  # type: ignore[misc]
-        @overload
-        def removesuffix(self: LiteralString, suffix: LiteralString, /) -> LiteralString: ...
-        @overload
-        def removesuffix(self, suffix: str, /) -> str: ...  # type: ignore[misc]
 
+    @overload
+    def removeprefix(self: LiteralString, prefix: LiteralString, /) -> LiteralString: ...
+    @overload
+    def removeprefix(self, prefix: str, /) -> str: ...  # type: ignore[misc]
+    @overload
+    def removesuffix(self: LiteralString, suffix: LiteralString, /) -> LiteralString: ...
+    @overload
+    def removesuffix(self, suffix: str, /) -> str: ...  # type: ignore[misc]
     def rfind(self, sub: str, start: SupportsIndex | None = ..., end: SupportsIndex | None = ..., /) -> int: ...
     def rindex(self, sub: str, start: SupportsIndex | None = ..., end: SupportsIndex | None = ..., /) -> int: ...
     @overload
@@ -666,10 +660,8 @@ class bytes(Sequence[int]):
     def lstrip(self, bytes: ReadableBuffer | None = None, /) -> bytes: ...
     def partition(self, sep: ReadableBuffer, /) -> tuple[bytes, bytes, bytes]: ...
     def replace(self, old: ReadableBuffer, new: ReadableBuffer, count: SupportsIndex = -1, /) -> bytes: ...
-    if sys.version_info >= (3, 9):
-        def removeprefix(self, prefix: ReadableBuffer, /) -> bytes: ...
-        def removesuffix(self, suffix: ReadableBuffer, /) -> bytes: ...
-
+    def removeprefix(self, prefix: ReadableBuffer, /) -> bytes: ...
+    def removesuffix(self, suffix: ReadableBuffer, /) -> bytes: ...
     def rfind(
         self, sub: ReadableBuffer | SupportsIndex, start: SupportsIndex | None = ..., end: SupportsIndex | None = ..., /
     ) -> int: ...
@@ -771,10 +763,8 @@ class bytearray(MutableSequence[int]):
     def partition(self, sep: ReadableBuffer, /) -> tuple[bytearray, bytearray, bytearray]: ...
     def pop(self, index: int = -1, /) -> int: ...
     def remove(self, value: int, /) -> None: ...
-    if sys.version_info >= (3, 9):
-        def removeprefix(self, prefix: ReadableBuffer, /) -> bytearray: ...
-        def removesuffix(self, suffix: ReadableBuffer, /) -> bytearray: ...
-
+    def removeprefix(self, prefix: ReadableBuffer, /) -> bytearray: ...
+    def removesuffix(self, suffix: ReadableBuffer, /) -> bytearray: ...
     def replace(self, old: ReadableBuffer, new: ReadableBuffer, count: SupportsIndex = -1, /) -> bytearray: ...
     def rfind(
         self, sub: ReadableBuffer | SupportsIndex, start: SupportsIndex | None = ..., end: SupportsIndex | None = ..., /
@@ -1009,8 +999,7 @@ class tuple(Sequence[_T_co]):
     def __rmul__(self, value: SupportsIndex, /) -> tuple[_T_co, ...]: ...
     def count(self, value: Any, /) -> int: ...
     def index(self, value: Any, start: SupportsIndex = 0, stop: SupportsIndex = sys.maxsize, /) -> int: ...
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+    def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
 
 # Doesn't exist at runtime, but deleting this breaks mypy and pyright. See:
 # https://github.com/python/typeshed/issues/7580
@@ -1092,8 +1081,7 @@ class list(MutableSequence[_T]):
     def __lt__(self, value: list[_T], /) -> bool: ...
     def __le__(self, value: list[_T], /) -> bool: ...
     def __eq__(self, value: object, /) -> bool: ...
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+    def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
 
 class dict(MutableMapping[_KT, _VT]):
     # __init__ should be kept roughly in line with `collections.UserDict.__init__`, which has similar semantics
@@ -1162,21 +1150,20 @@ class dict(MutableMapping[_KT, _VT]):
     def __eq__(self, value: object, /) -> bool: ...
     def __reversed__(self) -> Iterator[_KT]: ...
     __hash__: ClassVar[None]  # type: ignore[assignment]
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
-        @overload
-        def __or__(self, value: dict[_KT, _VT], /) -> dict[_KT, _VT]: ...
-        @overload
-        def __or__(self, value: dict[_T1, _T2], /) -> dict[_KT | _T1, _VT | _T2]: ...
-        @overload
-        def __ror__(self, value: dict[_KT, _VT], /) -> dict[_KT, _VT]: ...
-        @overload
-        def __ror__(self, value: dict[_T1, _T2], /) -> dict[_KT | _T1, _VT | _T2]: ...
-        # dict.__ior__ should be kept roughly in line with MutableMapping.update()
-        @overload  # type: ignore[misc]
-        def __ior__(self, value: SupportsKeysAndGetItem[_KT, _VT], /) -> Self: ...
-        @overload
-        def __ior__(self, value: Iterable[tuple[_KT, _VT]], /) -> Self: ...
+    def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+    @overload
+    def __or__(self, value: dict[_KT, _VT], /) -> dict[_KT, _VT]: ...
+    @overload
+    def __or__(self, value: dict[_T1, _T2], /) -> dict[_KT | _T1, _VT | _T2]: ...
+    @overload
+    def __ror__(self, value: dict[_KT, _VT], /) -> dict[_KT, _VT]: ...
+    @overload
+    def __ror__(self, value: dict[_T1, _T2], /) -> dict[_KT | _T1, _VT | _T2]: ...
+    # dict.__ior__ should be kept roughly in line with MutableMapping.update()
+    @overload  # type: ignore[misc]
+    def __ior__(self, value: SupportsKeysAndGetItem[_KT, _VT], /) -> Self: ...
+    @overload
+    def __ior__(self, value: Iterable[tuple[_KT, _VT]], /) -> Self: ...
 
 class set(MutableSet[_T]):
     @overload
@@ -1215,8 +1202,7 @@ class set(MutableSet[_T]):
     def __gt__(self, value: AbstractSet[object], /) -> bool: ...
     def __eq__(self, value: object, /) -> bool: ...
     __hash__: ClassVar[None]  # type: ignore[assignment]
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+    def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
 
 class frozenset(AbstractSet[_T_co]):
     @overload
@@ -1244,15 +1230,13 @@ class frozenset(AbstractSet[_T_co]):
     def __gt__(self, value: AbstractSet[object], /) -> bool: ...
     def __eq__(self, value: object, /) -> bool: ...
     def __hash__(self) -> int: ...
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+    def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
 
 class enumerate(Generic[_T]):
     def __new__(cls, iterable: Iterable[_T], start: int = 0) -> Self: ...
     def __iter__(self) -> Self: ...
     def __next__(self) -> tuple[int, _T]: ...
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+    def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
 
 @final
 class range(Sequence[int]):