bpo-44490: Improve typing module compatibility with types.Union

Lib/test/test_typing.py

@@ -315,6 +315,8 @@ def test_repr(self):
         self.assertEqual(repr(u), 'typing.Union[typing.List[int], int]')
         u = Union[list[int], dict[str, float]]
         self.assertEqual(repr(u), 'typing.Union[list[int], dict[str, float]]')
+        u = Union[int | float]
+        self.assertEqual(repr(u), 'typing.Union[int, float]')
 
     def test_cannot_subclass(self):
         with self.assertRaises(TypeError):
@@ -1449,6 +1451,8 @@ def test_basics(self):
         with self.assertRaises(TypeError):
             issubclass(SM1, SimpleMapping)
         self.assertIsInstance(SM1(), SimpleMapping)
+        T = TypeVar("T")
+        self.assertEqual(List[list[T] | float].__parameters__, (T,))
 
     def test_generic_errors(self):
         T = TypeVar('T')
@@ -1785,6 +1789,7 @@ def test_extended_generic_rules_repr(self):
     def test_generic_forward_ref(self):
         def foobar(x: List[List['CC']]): ...
         def foobar2(x: list[list[ForwardRef('CC')]]): ...
+        def foobar3(x: list[ForwardRef('CC')] | int): ...
         class CC: ...
         self.assertEqual(
             get_type_hints(foobar, globals(), locals()),
@@ -1794,6 +1799,10 @@ class CC: ...
             get_type_hints(foobar2, globals(), locals()),
             {'x': list[list[CC]]}
         )
+        self.assertEqual(
+            get_type_hints(foobar3, globals(), locals()),
+            {'x': list[CC] | int}
+        )
 
         T = TypeVar('T')
         AT = Tuple[T, ...]
@@ -2467,6 +2476,12 @@ def foo(a: Union['T']):
         self.assertEqual(get_type_hints(foo, globals(), locals()),
                          {'a': Union[T]})
 
+        def foo(a: tuple[ForwardRef('T')] | int):
+            pass
+
+        self.assertEqual(get_type_hints(foo, globals(), locals()),
+                         {'a': tuple[T] | int})
+
     def test_tuple_forward(self):
 
         def foo(a: Tuple['T']):
@@ -4390,6 +4405,9 @@ def test_no_paramspec_in__parameters__(self):
         self.assertNotIn(P, list[P].__parameters__)
         self.assertIn(T, tuple[T, P].__parameters__)
 
+        self.assertNotIn(P, (list[P] | int).__parameters__)
+        self.assertIn(T, (tuple[T, P] | int).__parameters__)
+
     def test_paramspec_in_nested_generics(self):
         # Although ParamSpec should not be found in __parameters__ of most
         # generics, they probably should be found when nested in
@@ -4399,8 +4417,10 @@ def test_paramspec_in_nested_generics(self):
         C1 = Callable[P, T]
         G1 = List[C1]
         G2 = list[C1]
+        G3 = list[C1] | int
         self.assertEqual(G1.__parameters__, (P, T))
         self.assertEqual(G2.__parameters__, (P, T))
+        self.assertEqual(G3.__parameters__, (P, T))
 
 
 class ConcatenateTests(BaseTestCase):

Lib/typing.py

@@ -196,7 +196,7 @@ def _type_repr(obj):
     return repr(obj)
 
 
-def _collect_type_vars(types, typevar_types=None):
+def _collect_type_vars(types_, typevar_types=None):
     """Collect all type variable contained
     in types in order of first appearance (lexicographic order). For example::
 
@@ -205,10 +205,10 @@ def _collect_type_vars(types, typevar_types=None):
     if typevar_types is None:
         typevar_types = TypeVar
     tvars = []
-    for t in types:
+    for t in types_:
         if isinstance(t, typevar_types) and t not in tvars:
             tvars.append(t)
-        if isinstance(t, (_GenericAlias, GenericAlias)):
+        if isinstance(t, (_GenericAlias, GenericAlias, types.Union)):
             tvars.extend([t for t in t.__parameters__ if t not in tvars])
     return tuple(tvars)
 
@@ -315,12 +315,14 @@ def _eval_type(t, globalns, localns, recursive_guard=frozenset()):
     """
     if isinstance(t, ForwardRef):
         return t._evaluate(globalns, localns, recursive_guard)
-    if isinstance(t, (_GenericAlias, GenericAlias)):
+    if isinstance(t, (_GenericAlias, GenericAlias, types.Union)):
         ev_args = tuple(_eval_type(a, globalns, localns, recursive_guard) for a in t.__args__)
         if ev_args == t.__args__:
             return t
         if isinstance(t, GenericAlias):
             return GenericAlias(t.__origin__, ev_args)
+        if isinstance(t, types.Union):
+            return functools.reduce(operator.or_, ev_args)
         else:
             return t.copy_with(ev_args)
     return t
@@ -1009,7 +1011,7 @@ def __getitem__(self, params):
         for arg in self.__args__:
             if isinstance(arg, self._typevar_types):
                 arg = subst[arg]
-            elif isinstance(arg, (_GenericAlias, GenericAlias)):
+            elif isinstance(arg, (_GenericAlias, GenericAlias, types.Union)):
                 subparams = arg.__parameters__
                 if subparams:
                     subargs = tuple(subst[x] for x in subparams)
@@ -1775,6 +1777,12 @@ def _strip_annotations(t):
         if stripped_args == t.__args__:
             return t
         return GenericAlias(t.__origin__, stripped_args)
+    if isinstance(t, types.Union):
+        stripped_args = tuple(_strip_annotations(a) for a in t.__args__)
+        if stripped_args == t.__args__:
+            return t
+        return functools.reduce(operator.or_, stripped_args)
+
     return t
 
 

Misc/NEWS.d/next/Core and Builtins/2021-07-06-22-22-15.bpo-44490.BJxPbZ.rst

@@ -0,0 +1,2 @@
+Fix ``typing`` module issues with ``types.Union`` parameters and arguments
+resolving. Patch provided by Yurii Karabas.