Python3.8 additions and changes (#3337)

* Add as_integer_ratio() to a few types

* Add dirs_exist_ok to copytree()

* int, float, complex accept __index__ args

Also fix complex.__init__ argument names

* Add __reversed__ to dict et al.

* Python 3.8 date(time) arithmetic fixes

* Add CodeType.replace()

stdlib/2and3/builtins.pyi

@@ -17,6 +17,11 @@ import sys
 if sys.version_info >= (3,):
     from typing import SupportsBytes, SupportsRound
 
+if sys.version_info >= (3, 8):
+    from typing import Literal
+else:
+    from typing_extensions import Literal
+
 _T = TypeVar('_T')
 _T_co = TypeVar('_T_co', covariant=True)
 _KT = TypeVar('_KT')
@@ -29,6 +34,9 @@ _T4 = TypeVar('_T4')
 _T5 = TypeVar('_T5')
 _TT = TypeVar('_TT', bound='type')
 
+class _SupportsIndex(Protocol):
+    def __index__(self) -> int: ...
+
 class object:
     __doc__: Optional[str]
     __dict__: Dict[str, Any]
@@ -129,10 +137,12 @@ class super(object):
 
 class int:
     @overload
-    def __init__(self, x: Union[Text, bytes, SupportsInt] = ...) -> None: ...
+    def __init__(self, x: Union[Text, bytes, SupportsInt, _SupportsIndex] = ...) -> None: ...
     @overload
     def __init__(self, x: Union[Text, bytes, bytearray], base: int) -> None: ...
 
+    if sys.version_info >= (3, 8):
+        def as_integer_ratio(self) -> Tuple[int, Literal[1]]: ...
     @property
     def real(self) -> int: ...
     @property
@@ -209,7 +219,7 @@ class int:
     def __index__(self) -> int: ...
 
 class float:
-    def __init__(self, x: Union[SupportsFloat, Text, bytes, bytearray] = ...) -> None: ...
+    def __init__(self, x: Union[SupportsFloat, _SupportsIndex, Text, bytes, bytearray] = ...) -> None: ...
     def as_integer_ratio(self) -> Tuple[int, int]: ...
     def hex(self) -> str: ...
     def is_integer(self) -> bool: ...
@@ -271,11 +281,9 @@ class float:
 
 class complex:
     @overload
-    def __init__(self, re: float = ..., im: float = ...) -> None: ...
+    def __init__(self, real: float = ..., imag: float = ...) -> None: ...
     @overload
-    def __init__(self, s: str) -> None: ...
-    @overload
-    def __init__(self, s: SupportsComplex) -> None: ...
+    def __init__(self, real: Union[str, SupportsComplex, _SupportsIndex]) -> None: ...
 
     @property
     def real(self) -> float: ...
@@ -987,6 +995,8 @@ class dict(MutableMapping[_KT, _VT], Generic[_KT, _VT]):
     def __setitem__(self, k: _KT, v: _VT) -> None: ...
     def __delitem__(self, v: _KT) -> None: ...
     def __iter__(self) -> Iterator[_KT]: ...
+    if sys.version_info >= (3, 8):
+        def __reversed__(self) -> Iterator[_KT]: ...
     def __str__(self) -> str: ...
     __hash__: None  # type: ignore
 
@@ -1117,8 +1127,6 @@ if sys.version_info < (3,):
 if sys.version_info >= (3,):
     def ascii(__o: object) -> str: ...
 
-class _SupportsIndex(Protocol):
-    def __index__(self) -> int: ...
 def bin(__number: Union[int, _SupportsIndex]) -> str: ...
 
 if sys.version_info >= (3, 7):

stdlib/2and3/datetime.pyi

@@ -1,9 +1,8 @@
 import sys
 from time import struct_time
-from typing import (
-    AnyStr, Optional, SupportsAbs, Tuple, Union, overload,
-    ClassVar,
-)
+from typing import AnyStr, Optional, SupportsAbs, Tuple, Union, overload, ClassVar, Type, TypeVar
+
+_S = TypeVar("_S")
 
 if sys.version_info >= (3,):
     _Text = str
@@ -68,7 +67,10 @@ class date:
     def __lt__(self, other: date) -> bool: ...
     def __ge__(self, other: date) -> bool: ...
     def __gt__(self, other: date) -> bool: ...
-    def __add__(self, other: timedelta) -> date: ...
+    if sys.version_info >= (3, 8):
+        def __add__(self: _S, other: timedelta) -> _S: ...
+    else:
+        def __add__(self, other: timedelta) -> date: ...
     @overload
     def __sub__(self, other: timedelta) -> date: ...
     @overload
@@ -227,8 +229,16 @@ class datetime(date):
     def today(cls) -> datetime: ...
     @classmethod
     def fromordinal(cls, n: int) -> datetime: ...
-    @classmethod
-    def now(cls, tz: Optional[_tzinfo] = ...) -> datetime: ...
+    if sys.version_info >= (3, 8):
+        @classmethod
+        def now(cls: Type[_S], tz: Optional[_tzinfo] = ...) -> _S: ...
+    else:
+        @overload
+        @classmethod
+        def now(cls: Type[_S], tz: None = ...) -> _S: ...
+        @overload
+        @classmethod
+        def now(cls, tz: _tzinfo) -> datetime: ...
     @classmethod
     def utcnow(cls) -> datetime: ...
     if sys.version_info >= (3, 6):
@@ -261,7 +271,9 @@ class datetime(date):
         def replace(self, year: int = ..., month: int = ..., day: int = ..., hour: int = ...,
                     minute: int = ..., second: int = ..., microsecond: int = ..., tzinfo:
                     Optional[_tzinfo] = ...) -> datetime: ...
-    if sys.version_info >= (3, 3):
+    if sys.version_info >= (3, 8):
+        def astimezone(self: _S, tz: Optional[_tzinfo] = ...) -> _S: ...
+    elif sys.version_info >= (3, 3):
         def astimezone(self, tz: Optional[_tzinfo] = ...) -> datetime: ...
     else:
         def astimezone(self, tz: _tzinfo) -> datetime: ...
@@ -279,7 +291,10 @@ class datetime(date):
     def __lt__(self, other: datetime) -> bool: ...  # type: ignore
     def __ge__(self, other: datetime) -> bool: ...  # type: ignore
     def __gt__(self, other: datetime) -> bool: ...  # type: ignore
-    def __add__(self, other: timedelta) -> datetime: ...
+    if sys.version_info >= (3, 8):
+        def __add__(self: _S, other: timedelta) -> _S: ...
+    else:
+        def __add__(self, other: timedelta) -> datetime: ...
     @overload  # type: ignore
     def __sub__(self, other: datetime) -> timedelta: ...
     @overload

stdlib/2and3/fractions.pyi

@@ -4,7 +4,7 @@
 # Note: these stubs are incomplete. The more complex type
 # signatures are currently omitted. Also see numbers.pyi.
 
-from typing import Optional, TypeVar, Union, overload, Any
+from typing import Optional, TypeVar, Union, overload, Any, Tuple
 from numbers import Real, Integral, Rational
 from decimal import Decimal
 import sys
@@ -42,6 +42,8 @@ class Fraction(Rational):
     def from_decimal(cls, dec: Decimal) -> Fraction: ...
     def limit_denominator(self, max_denominator: int = ...) -> Fraction: ...
 
+    if sys.version_info >= (3, 8):
+        def as_integer_ratio(self) -> Tuple[int, int]: ...
     @property
     def numerator(self) -> int: ...
     @property

stdlib/2and3/shutil.pyi

@@ -72,7 +72,17 @@ else:
 
 def ignore_patterns(*patterns: _Path) -> Callable[[Any, List[_AnyStr]], Set[_AnyStr]]: ...
 
-if sys.version_info >= (3,):
+if sys.version_info >= (3, 8):
+    def copytree(
+        src: _Path,
+        dst: _Path,
+        symlinks: bool = ...,
+        ignore: Union[None, Callable[[str, List[str]], Iterable[str]], Callable[[_Path, List[str]], Iterable[str]]] = ...,
+        copy_function: Callable[[str, str], None] = ...,
+        ignore_dangling_symlinks: bool = ...,
+        dirs_exist_ok: bool = ...,
+    ) -> _PathReturn: ...
+elif sys.version_info >= (3,):
     def copytree(src: _Path, dst: _Path, symlinks: bool = ...,
                  ignore: Union[None,
                                Callable[[str, List[str]], Iterable[str]],