bpo-41428: Implementation for PEP 604 (GH-21515)

See https://www.python.org/dev/peps/pep-0604/ for more information.

Co-authored-by: Pablo Galindo <[email protected]>

Author: maggiemoss

Include/internal/pycore_unionobject.h

@@ -0,0 +1,17 @@
+#ifndef Py_INTERNAL_UNIONOBJECT_H
+#define Py_INTERNAL_UNIONOBJECT_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef Py_BUILD_CORE
+#  error "this header requires Py_BUILD_CORE define"
+#endif
+
+PyAPI_FUNC(PyObject *) _Py_Union(PyObject *args);
+PyAPI_DATA(PyTypeObject) _Py_UnionType;
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_INTERNAL_UNIONOBJECT_H */

Lib/test/test_isinstance.py

@@ -4,6 +4,7 @@
 
 import unittest
 import sys
+import typing
 
 
 
@@ -208,6 +209,25 @@ def test_isinstance_abstract(self):
         self.assertEqual(False, isinstance(AbstractChild(), Super))
         self.assertEqual(False, isinstance(AbstractChild(), Child))
 
+    def test_isinstance_with_or_union(self):
+        self.assertTrue(isinstance(Super(), Super | int))
+        self.assertFalse(isinstance(None, str | int))
+        self.assertTrue(isinstance(3, str | int))
+        self.assertTrue(isinstance("", str | int))
+        self.assertTrue(isinstance([], typing.List | typing.Tuple))
+        self.assertTrue(isinstance(2, typing.List | int))
+        self.assertFalse(isinstance(2, typing.List | typing.Tuple))
+        self.assertTrue(isinstance(None, int | None))
+        self.assertFalse(isinstance(3.14, int | str))
+        with self.assertRaises(TypeError):
+            isinstance(2, list[int])
+        with self.assertRaises(TypeError):
+            isinstance(2, list[int] | int)
+        with self.assertRaises(TypeError):
+            isinstance(2, int | str | list[int] | float)
+
+
+
     def test_subclass_normal(self):
         # normal classes
         self.assertEqual(True, issubclass(Super, Super))
@@ -217,6 +237,8 @@ def test_subclass_normal(self):
         self.assertEqual(True, issubclass(Child, Child))
         self.assertEqual(True, issubclass(Child, Super))
         self.assertEqual(False, issubclass(Child, AbstractSuper))
+        self.assertTrue(issubclass(typing.List, typing.List|typing.Tuple))
+        self.assertFalse(issubclass(int, typing.List|typing.Tuple))
 
     def test_subclass_abstract(self):
         # abstract classes
@@ -251,6 +273,16 @@ def test_isinstance_recursion_limit(self):
         # blown
         self.assertRaises(RecursionError, blowstack, isinstance, '', str)
 
+    def test_subclass_with_union(self):
+        self.assertTrue(issubclass(int, int | float | int))
+        self.assertTrue(issubclass(str, str | Child | str))
+        self.assertFalse(issubclass(dict, float|str))
+        self.assertFalse(issubclass(object, float|str))
+        with self.assertRaises(TypeError):
+            issubclass(2, Child | Super)
+        with self.assertRaises(TypeError):
+            issubclass(int, list[int] | Child)
+
     def test_issubclass_refcount_handling(self):
         # bpo-39382: abstract_issubclass() didn't hold item reference while
         # peeking in the bases tuple, in the single inheritance case.

Lib/test/test_types.py

@@ -2,13 +2,20 @@
 
 from test.support import run_with_locale
 import collections.abc
+from collections import namedtuple
 import inspect
 import pickle
 import locale
 import sys
 import types
 import unittest.mock
 import weakref
+import typing
+
+class Example:
+    pass
+
+class Forward: ...
 
 class TypesTests(unittest.TestCase):
 
@@ -598,6 +605,113 @@ def test_method_descriptor_types(self):
         self.assertIsInstance(int.from_bytes, types.BuiltinMethodType)
         self.assertIsInstance(int.__new__, types.BuiltinMethodType)
 
+    def test_or_types_operator(self):
+        self.assertEqual(int | str, typing.Union[int, str])
+        self.assertNotEqual(int | list, typing.Union[int, str])
+        self.assertEqual(str | int, typing.Union[int, str])
+        self.assertEqual(int | None, typing.Union[int, None])
+        self.assertEqual(None | int, typing.Union[int, None])
+        self.assertEqual(int | str | list, typing.Union[int, str, list])
+        self.assertEqual(int | (str | list), typing.Union[int, str, list])
+        self.assertEqual(str | (int | list), typing.Union[int, str, list])
+        self.assertEqual(typing.List | typing.Tuple, typing.Union[typing.List, typing.Tuple])
+        self.assertEqual(typing.List[int] | typing.Tuple[int], typing.Union[typing.List[int], typing.Tuple[int]])
+        self.assertEqual(typing.List[int] | None, typing.Union[typing.List[int], None])
+        self.assertEqual(None | typing.List[int], typing.Union[None, typing.List[int]])
+        self.assertEqual(str | float | int | complex | int, (int | str) | (float | complex))
+        self.assertEqual(typing.Union[str, int, typing.List[int]], str | int | typing.List[int])
+        self.assertEqual(int | int, int)
+        self.assertEqual(
+            BaseException |
+            bool |
+            bytes |
+            complex |
+            float |
+            int |
+            list |
+            map |
+            set,
+            typing.Union[
+                BaseException,
+                bool,
+                bytes,
+                complex,
+                float,
+                int,
+                list,
+                map,
+                set,
+            ])
+        with self.assertRaises(TypeError):
+            int | 3
+        with self.assertRaises(TypeError):
+            3 | int
+        with self.assertRaises(TypeError):
+            Example() | int
+        with self.assertRaises(TypeError):
+            (int | str) < typing.Union[str, int]
+        with self.assertRaises(TypeError):
+            (int | str) < (int | bool)
+        with self.assertRaises(TypeError):
+            (int | str) <= (int | str)
+        with self.assertRaises(TypeError):
+            # Check that we don't crash if typing.Union does not have a tuple in __args__
+            x = typing.Union[str, int]
+            x.__args__ = [str, int]
+            (int | str ) == x
+
+    def test_or_type_operator_with_TypeVar(self):
+        TV = typing.TypeVar('T')
+        assert TV | str == typing.Union[TV, str]
+        assert str | TV == typing.Union[str, TV]
+
+    def test_or_type_operator_with_forward(self):
+        T = typing.TypeVar('T')
+        ForwardAfter = T | 'Forward'
+        ForwardBefore = 'Forward' | T
+        def forward_after(x: ForwardAfter[int]) -> None: ...
+        def forward_before(x: ForwardBefore[int]) -> None: ...
+        assert typing.get_args(typing.get_type_hints(forward_after)['x']) == (int, Forward)
+        assert typing.get_args(typing.get_type_hints(forward_before)['x']) == (int, Forward)
+
+    def test_or_type_operator_with_Protocol(self):
+        class Proto(typing.Protocol):
+            def meth(self) -> int:
+                ...
+        assert Proto | str == typing.Union[Proto, str]
+
+    def test_or_type_operator_with_Alias(self):
+        assert list | str == typing.Union[list, str]
+        assert typing.List | str == typing.Union[typing.List, str]
+
+    def test_or_type_operator_with_NamedTuple(self):
+        NT=namedtuple('A', ['B', 'C', 'D'])
+        assert NT | str == typing.Union[NT,str]
+
+    def test_or_type_operator_with_TypedDict(self):
+        class Point2D(typing.TypedDict):
+            x: int
+            y: int
+            label: str
+        assert Point2D | str == typing.Union[Point2D, str]
+
+    def test_or_type_operator_with_NewType(self):
+        UserId = typing.NewType('UserId', int)
+        assert UserId | str == typing.Union[UserId, str]
+
+    def test_or_type_operator_with_IO(self):
+        assert typing.IO | str == typing.Union[typing.IO, str]
+
+    def test_or_type_operator_with_SpecialForm(self):
+        assert typing.Any | str == typing.Union[typing.Any, str]
+        assert typing.NoReturn | str == typing.Union[typing.NoReturn, str]
+        assert typing.Optional[int] | str == typing.Union[typing.Optional[int], str]
+        assert typing.Optional[int] | str == typing.Union[int, str, None]
+        assert typing.Union[int, bool] | str == typing.Union[int, bool, str]
+
+    def test_or_type_repr(self):
+        assert repr(int | None) == "int | None"
+        assert repr(int | typing.GenericAlias(list, int)) == "int | list[int]"
 
 class MappingProxyTests(unittest.TestCase):
     mappingproxy = types.MappingProxyType

Lib/test/test_typing.py

@@ -244,8 +244,6 @@ def test_subclass_error(self):
             issubclass(int, Union)
         with self.assertRaises(TypeError):
             issubclass(Union, int)
-        with self.assertRaises(TypeError):
-            issubclass(int, Union[int, str])
         with self.assertRaises(TypeError):
             issubclass(Union[int, str], int)
 
@@ -347,10 +345,6 @@ def test_empty(self):
         with self.assertRaises(TypeError):
             Union[()]
 
-    def test_union_instance_type_error(self):
-        with self.assertRaises(TypeError):
-            isinstance(42, Union[int, str])
-
     def test_no_eval_union(self):
         u = Union[int, str]
         def f(x: u): ...

Lib/types.py

@@ -294,6 +294,7 @@ def wrapped(*args, **kwargs):
 
 
 GenericAlias = type(list[int])
+Union = type(int | str)
 
 
 __all__ = [n for n in globals() if n[:1] != '_']

Lib/typing.py

@@ -117,7 +117,6 @@
 # namespace, but excluded from __all__ because they might stomp on
 # legitimate imports of those modules.
 
-
 def _type_check(arg, msg, is_argument=True):
     """Check that the argument is a type, and return it (internal helper).
 
@@ -145,7 +144,7 @@ def _type_check(arg, msg, is_argument=True):
         return arg
     if isinstance(arg, _SpecialForm) or arg in (Generic, Protocol):
         raise TypeError(f"Plain {arg} is not valid as type argument")
-    if isinstance(arg, (type, TypeVar, ForwardRef)):
+    if isinstance(arg, (type, TypeVar, ForwardRef, types.Union)):
         return arg
     if not callable(arg):
         raise TypeError(f"{msg} Got {arg!r:.100}.")
@@ -205,7 +204,7 @@ def _remove_dups_flatten(parameters):
     # Flatten out Union[Union[...], ...].
     params = []
     for p in parameters:
-        if isinstance(p, _UnionGenericAlias):
+        if isinstance(p, (_UnionGenericAlias, types.Union)):
             params.extend(p.__args__)
         elif isinstance(p, tuple) and len(p) > 0 and p[0] is Union:
             params.extend(p[1:])
@@ -586,6 +585,12 @@ def __init__(self, name, *constraints, bound=None,
         if def_mod != 'typing':
             self.__module__ = def_mod
 
+    def __or__(self, right):
+        return Union[self, right]
+
+    def __ror__(self, right):
+        return Union[self, right]
+
     def __repr__(self):
         if self.__covariant__:
             prefix = '+'
@@ -693,6 +698,12 @@ def __eq__(self, other):
     def __hash__(self):
         return hash((self.__origin__, self.__args__))
 
+    def __or__(self, right):
+        return Union[self, right]
+
+    def __ror__(self, right):
+        return Union[self, right]
+
     @_tp_cache
     def __getitem__(self, params):
         if self.__origin__ in (Generic, Protocol):
@@ -792,6 +803,11 @@ def __subclasscheck__(self, cls):
     def __reduce__(self):
         return self._name
 
+    def __or__(self, right):
+        return Union[self, right]
+
+    def __ror__(self, right):
+        return Union[self, right]
 
 class _CallableGenericAlias(_GenericAlias, _root=True):
     def __repr__(self):
@@ -878,6 +894,15 @@ def __repr__(self):
                 return f'typing.Optional[{_type_repr(args[0])}]'
         return super().__repr__()
 
+    def __instancecheck__(self, obj):
+        return self.__subclasscheck__(type(obj))
+
+    def __subclasscheck__(self, cls):
+        for arg in self.__args__:
+            if issubclass(cls, arg):
+                return True
+
+
 
 class Generic:
     """Abstract base class for generic types.

Makefile.pre.in

@@ -432,6 +432,7 @@ OBJECT_OBJS=	\
 		Objects/typeobject.o \
 		Objects/unicodeobject.o \
 		Objects/unicodectype.o \
+		Objects/unionobject.o \
 		Objects/weakrefobject.o
 
 ##########################################################################
@@ -1128,6 +1129,7 @@ PYTHON_HEADERS= \
 		$(srcdir)/Include/internal/pycore_sysmodule.h \
 		$(srcdir)/Include/internal/pycore_traceback.h \
 		$(srcdir)/Include/internal/pycore_tuple.h \
+		$(srcdir)/Include/internal/pycore_unionobject.h \
 		$(srcdir)/Include/internal/pycore_warnings.h \
 		$(DTRACE_HEADERS)
 

Misc/NEWS.d/next/Core and Builtins/2020-07-28-22-43-27.bpo-41428.FM6xsI.rst

@@ -0,0 +1 @@
+Implement PEP 604. This supports (int | str) etc. in place of Union[str, int].

Objects/abstract.c

@@ -1,6 +1,7 @@
 /* Abstract Object Interface (many thanks to Jim Fulton) */
 
 #include "Python.h"
+#include "pycore_unionobject.h"      // _Py_UnionType && _Py_Union()
 #include "pycore_abstract.h"      // _PyIndex_Check()
 #include "pycore_ceval.h"         // _Py_EnterRecursiveCall()
 #include "pycore_pyerrors.h"      // _PyErr_Occurred()
@@ -839,7 +840,6 @@ binary_op(PyObject *v, PyObject *w, const int op_slot, const char *op_name)
                 Py_TYPE(w)->tp_name);
             return NULL;
         }
-
         return binop_type_error(v, w, op_name);
     }
     return result;
@@ -2412,7 +2412,6 @@ object_isinstance(PyObject *inst, PyObject *cls)
     PyObject *icls;
     int retval;
     _Py_IDENTIFIER(__class__);
-
     if (PyType_Check(cls)) {
         retval = PyObject_TypeCheck(inst, (PyTypeObject *)cls);
         if (retval == 0) {
@@ -2432,7 +2431,7 @@ object_isinstance(PyObject *inst, PyObject *cls)
     }
     else {
         if (!check_class(cls,
-            "isinstance() arg 2 must be a type or tuple of types"))
+            "isinstance() arg 2 must be a type, a tuple of types or a union"))
             return -1;
         retval = _PyObject_LookupAttrId(inst, &PyId___class__, &icls);
         if (icls != NULL) {
@@ -2525,10 +2524,14 @@ recursive_issubclass(PyObject *derived, PyObject *cls)
     if (!check_class(derived,
                      "issubclass() arg 1 must be a class"))
         return -1;
-    if (!check_class(cls,
-                    "issubclass() arg 2 must be a class"
-                    " or tuple of classes"))
+
+    PyTypeObject *type = Py_TYPE(cls);
+    int is_union = (PyType_Check(type) && type == &_Py_UnionType);
+    if (!is_union && !check_class(cls,
+                            "issubclass() arg 2 must be a class,"
+                            " a tuple of classes, or a union.")) {
         return -1;
+    }
 
     return abstract_issubclass(derived, cls);
 }