Support ParamSpec in __parameters__ of typing and builtin GenericAlias

also reduced runtime checks

Lib/test/test_typing.py

@@ -4266,17 +4266,17 @@ def test_valid_uses(self):
         T = TypeVar('T')
         C1 = Callable[P, int]
         self.assertEqual(C1.__args__, (P, int))
-        self.assertEqual(C1.__parameters__, ())
+        self.assertEqual(C1.__parameters__, (P,))
         C2 = Callable[P, T]
         self.assertEqual(C2.__args__, (P, T))
-        self.assertEqual(C2.__parameters__, (T,))
+        self.assertEqual(C2.__parameters__, (P, T))
         # Test collections.abc.Callable too.
         C3 = collections.abc.Callable[P, int]
         self.assertEqual(C3.__args__, (P, int))
-        self.assertEqual(C3.__parameters__, ())
+        self.assertEqual(C3.__parameters__, (P,))
         C4 = collections.abc.Callable[P, T]
         self.assertEqual(C4.__args__, (P, T))
-        self.assertEqual(C4.__parameters__, (T,))
+        self.assertEqual(C4.__parameters__, (P, T))
 
         # ParamSpec instances should also have args and kwargs attributes.
         self.assertIn('args', dir(P))
@@ -4306,7 +4306,7 @@ def test_union_unique(self):
         self.assertNotEqual(Union[P1, int], Union[P1])
         self.assertNotEqual(Union[P1, int], Union[int])
         self.assertEqual(Union[P1, int].__args__, (P1, int))
-        self.assertEqual(Union[P1, int].__parameters__, ())
+        self.assertEqual(Union[P1, int].__parameters__, (P1,))
         self.assertIs(Union[P1, int].__origin__, Union)
 
     def test_repr(self):
@@ -4352,18 +4352,18 @@ def test_valid_uses(self):
         T = TypeVar('T')
         C1 = Callable[Concatenate[int, P], int]
         self.assertEqual(C1.__args__, (Concatenate[int, P], int))
-        self.assertEqual(C1.__parameters__, ())
+        self.assertEqual(C1.__parameters__, (P,))
         C2 = Callable[Concatenate[int, T, P], T]
         self.assertEqual(C2.__args__, (Concatenate[int, T, P], T))
-        self.assertEqual(C2.__parameters__, (T,))
+        self.assertEqual(C2.__parameters__, (T, P))
 
         # Test collections.abc.Callable too.
         C3 = collections.abc.Callable[Concatenate[int, P], int]
         self.assertEqual(C3.__args__, (Concatenate[int, P], int))
-        self.assertEqual(C3.__parameters__, ())
+        self.assertEqual(C3.__parameters__, (P,))
         C4 = collections.abc.Callable[Concatenate[int, T, P], T]
         self.assertEqual(C4.__args__, (Concatenate[int, T, P], T))
-        self.assertEqual(C4.__parameters__, (T,))
+        self.assertEqual(C4.__parameters__, (T, P))
 
 
 class AllTests(BaseTestCase):

Lib/typing.py

@@ -180,14 +180,14 @@ def _type_repr(obj):
 
 
 def _collect_type_vars(types):
-    """Collect all type variable contained in types in order of
-    first appearance (lexicographic order). For example::
+    """Collect all type variable and parameter specification variables contained
+    in types in order of first appearance (lexicographic order). For example::
 
         _collect_type_vars((T, List[S, T])) == (T, S)
     """
     tvars = []
     for t in types:
-        if isinstance(t, TypeVar) and t not in tvars:
+        if isinstance(t, (TypeVar, ParamSpec)) and t not in tvars:
             tvars.append(t)
         if isinstance(t, (_GenericAlias, GenericAlias)):
             tvars.extend([t for t in t.__parameters__ if t not in tvars])
@@ -529,10 +529,7 @@ def Concatenate(self, parameters):
 
        Callable[Concatenate[int, P], int]
 
-    .. seealso::
-
-       :pep:`612` -- Parameter Specification Variables
-
+    See PEP 612 for detailed information.
     """
     if parameters == ():
         raise TypeError("Cannot take a Concatenate of no types.")
@@ -1008,8 +1005,9 @@ def __getitem__(self, params):
             params = (Ellipsis, result)
         else:
             if not isinstance(args, (list, ParamSpec, _ConcatenateGenericAlias)):
-                raise TypeError(f"Callable[args, result]: args must be a list."
-                                f" Got {args}")
+                raise TypeError(f"Callable[args, result]: args must be a list, "
+                                f"ParamSpec or Concatenate. "
+                                f"Got {args}")
             if isinstance(args, list):
                 params = (tuple(args), result)
         return self.__getitem_inner__(params)
@@ -1092,12 +1090,7 @@ def __hash__(self):
 
 
 class _ConcatenateGenericAlias(_GenericAlias, _root=True):
-
-    def __or__(self, right):
-        return NotImplemented
-
-    def __ror__(self, right):
-        return NotImplemented
+    pass
 
 
 class Generic:

Objects/genericaliasobject.c

@@ -156,13 +156,14 @@ ga_repr(PyObject *self)
     return NULL;
 }
 
-// isinstance(obj, TypeVar) without importing typing.py.
+// isinstance(obj, (TypeVar, ParamSpec)) without importing typing.py.
 // Returns -1 for errors.
 static int
 is_typevar(PyObject *obj)
 {
     PyTypeObject *type = Py_TYPE(obj);
-    if (strcmp(type->tp_name, "TypeVar") != 0) {
+    if ((strcmp(type->tp_name, "TypeVar") & 
+         strcmp(type->tp_name, "ParamSpec")) != 0) {
         return 0;
     }
     PyObject *module = PyObject_GetAttrString((PyObject *)type, "__module__");