Merge branch 'main' into fastmock

* main:
  pythongh-99540: Constant hash for _PyNone_Type to aid reproducibility (pythonGH-99541)
  pythongh-100039: enhance __signature__ to work with str and callables (pythonGH-100168)
  pythongh-99830: asyncio: Document returns of remove_{reader,writer} (python#100302)
  "Compound statement" docs: Fix with-statement step indexing (python#100286)
  pythonGH-90043: Handle NaNs in COMPARE_OP_FLOAT_JUMP (pythonGH-100278)

Author: carljm

Doc/library/asyncio-eventloop.rst

@@ -932,7 +932,8 @@ Watching file descriptors
 
 .. method:: loop.remove_reader(fd)
 
-   Stop monitoring the *fd* file descriptor for read availability.
+   Stop monitoring the *fd* file descriptor for read availability. Returns
+   ``True`` if *fd* was previously being monitored for reads.
 
 .. method:: loop.add_writer(fd, callback, *args)
 
@@ -945,7 +946,8 @@ Watching file descriptors
 
 .. method:: loop.remove_writer(fd)
 
-   Stop monitoring the *fd* file descriptor for write availability.
+   Stop monitoring the *fd* file descriptor for write availability. Returns
+   ``True`` if *fd* was previously being monitored for writes.
 
 See also :ref:`Platform Support <asyncio-platform-support>` section
 for some limitations of these methods.

Doc/reference/compound_stmts.rst

@@ -506,7 +506,7 @@ The execution of the :keyword:`with` statement with one "item" proceeds as follo
       method returns without an error, then :meth:`__exit__` will always be
       called. Thus, if an error occurs during the assignment to the target list,
       it will be treated the same as an error occurring within the suite would
-      be. See step 6 below.
+      be. See step 7 below.
 
 #. The suite is executed.
 

Lib/enum.py

@@ -685,7 +685,7 @@ def __new__(metacls, cls, bases, classdict, *, boundary=None, _simple=False, **k
                         'member order does not match _order_:\n  %r\n  %r'
                         % (enum_class._member_names_, _order_)
                         )
-
+        #
         return enum_class
 
     def __bool__(cls):
@@ -1083,6 +1083,13 @@ class Enum(metaclass=EnumType):
     attributes -- see the documentation for details.
     """
 
+    @classmethod
+    def __signature__(cls):
+        if cls._member_names_:
+            return '(*values)'
+        else:
+            return '(new_class_name, /, names, *, module=None, qualname=None, type=None, start=1, boundary=None)'
+
     def __new__(cls, value):
         # all enum instances are actually created during class construction
         # without calling this method; this method is called by the metaclass'

Lib/inspect.py

@@ -2443,10 +2443,18 @@ def _signature_from_callable(obj, *,
         pass
     else:
         if sig is not None:
+            # since __text_signature__ is not writable on classes, __signature__
+            # may contain text (or be a callable that returns text);
+            # if so, convert it
+            o_sig = sig
+            if not isinstance(sig, (Signature, str)) and callable(sig):
+                sig = sig()
+            if isinstance(sig, str):
+                sig = _signature_fromstr(sigcls, obj, sig)
             if not isinstance(sig, Signature):
                 raise TypeError(
                     'unexpected object {!r} in __signature__ '
-                    'attribute'.format(sig))
+                    'attribute'.format(o_sig))
             return sig
 
     try:

Lib/test/test_enum.py

@@ -4259,7 +4259,7 @@ class TestEnumTypeSubclassing(unittest.TestCase):
 Help on class Color in module %s:
 
 class Color(enum.Enum)
- |  Color(value, names=None, *values, module=None, qualname=None, type=None, start=1, boundary=None)
+ |  Color(*values)
  |
  |  Method resolution order:
  |      Color
@@ -4315,7 +4315,7 @@ class Color(enum.Enum)
 Help on class Color in module %s:
 
 class Color(enum.Enum)
- |  Color(value, names=None, *values, module=None, qualname=None, type=None, start=1)
+ |  Color(*values)
  |
  |  Method resolution order:
  |      Color
@@ -4462,6 +4462,27 @@ def test_inspect_classify_class_attrs(self):
         if failed:
             self.fail("result does not equal expected, see print above")
 
+    def test_inspect_signatures(self):
+        from inspect import signature, Signature, Parameter
+        self.assertEqual(
+                signature(Enum),
+                Signature([
+                    Parameter('new_class_name', Parameter.POSITIONAL_ONLY),
+                    Parameter('names', Parameter.POSITIONAL_OR_KEYWORD),
+                    Parameter('module', Parameter.KEYWORD_ONLY, default=None),
+                    Parameter('qualname', Parameter.KEYWORD_ONLY, default=None),
+                    Parameter('type', Parameter.KEYWORD_ONLY, default=None),
+                    Parameter('start', Parameter.KEYWORD_ONLY, default=1),
+                    Parameter('boundary', Parameter.KEYWORD_ONLY, default=None),
+                    ]),
+                )
+        self.assertEqual(
+                signature(enum.FlagBoundary),
+                Signature([
+                    Parameter('values', Parameter.VAR_POSITIONAL),
+                    ]),
+                )
+
     def test_test_simple_enum(self):
         @_simple_enum(Enum)
         class SimpleColor:

Lib/test/test_inspect.py

@@ -3614,6 +3614,38 @@ def foo(): pass
                 self.assertEqual(signature_func(foo), inspect.Signature())
         self.assertEqual(inspect.get_annotations(foo), {})
 
+    def test_signature_as_str(self):
+        self.maxDiff = None
+        class S:
+            __signature__ = '(a, b=2)'
+
+        self.assertEqual(self.signature(S),
+                         ((('a', ..., ..., 'positional_or_keyword'),
+                           ('b', 2, ..., 'positional_or_keyword')),
+                          ...))
+
+    def test_signature_as_callable(self):
+        # __signature__ should be either a staticmethod or a bound classmethod
+        class S:
+            @classmethod
+            def __signature__(cls):
+                return '(a, b=2)'
+
+        self.assertEqual(self.signature(S),
+                         ((('a', ..., ..., 'positional_or_keyword'),
+                           ('b', 2, ..., 'positional_or_keyword')),
+                          ...))
+
+        class S:
+            @staticmethod
+            def __signature__():
+                return '(a, b=2)'
+
+        self.assertEqual(self.signature(S),
+                         ((('a', ..., ..., 'positional_or_keyword'),
+                           ('b', 2, ..., 'positional_or_keyword')),
+                          ...))
+
 
 class TestParameterObject(unittest.TestCase):
     def test_signature_parameter_kinds(self):

Misc/NEWS.d/next/Core and Builtins/2022-12-10-20-00-13.gh-issue-99540.ZZZHeP.rst

@@ -0,0 +1 @@
+``None`` now hashes to a constant value. This is not a requirements change.

Misc/NEWS.d/next/Core and Builtins/2022-12-15-00-50-25.gh-issue-90043.gyoKdx.rst

@@ -0,0 +1,2 @@
+Handle NaNs when specializing :opcode:`COMPARE_OP` for :class:`float`
+values.

Misc/NEWS.d/next/Library/2022-12-10-20-52-28.gh-issue-100039.zDqjT4.rst

@@ -0,0 +1 @@
+Improve signatures for enums and flags.

Objects/object.c

@@ -1641,6 +1641,11 @@ none_bool(PyObject *v)
     return 0;
 }
 
+static Py_hash_t none_hash(PyObject *v)
+{
+    return 0xFCA86420;
+}
+
 static PyNumberMethods none_as_number = {
     0,                          /* nb_add */
     0,                          /* nb_subtract */
@@ -1692,7 +1697,7 @@ PyTypeObject _PyNone_Type = {
     &none_as_number,    /*tp_as_number*/
     0,                  /*tp_as_sequence*/
     0,                  /*tp_as_mapping*/
-    0,                  /*tp_hash */
+    (hashfunc)none_hash,/*tp_hash */
     0,                  /*tp_call */
     0,                  /*tp_str */
     0,                  /*tp_getattro */

Python/bytecodes.c

@@ -2024,13 +2024,11 @@ dummy_func(
             // Combined: COMPARE_OP (float ? float) + POP_JUMP_IF_(true/false)
             DEOPT_IF(!PyFloat_CheckExact(left), COMPARE_OP);
             DEOPT_IF(!PyFloat_CheckExact(right), COMPARE_OP);
+            STAT_INC(COMPARE_OP, hit);
             double dleft = PyFloat_AS_DOUBLE(left);
             double dright = PyFloat_AS_DOUBLE(right);
-            // 1 if <, 2 if ==, 4 if >; this matches when _to_jump_mask
-            int sign_ish = 2*(dleft > dright) + 2 - (dleft < dright);
-            DEOPT_IF(isnan(dleft), COMPARE_OP);
-            DEOPT_IF(isnan(dright), COMPARE_OP);
-            STAT_INC(COMPARE_OP, hit);
+            // 1 if NaN, 2 if <, 4 if >, 8 if ==; this matches when_to_jump_mask
+            int sign_ish = 1 << (2 * (dleft >= dright) + (dleft <= dright));
             _Py_DECREF_SPECIALIZED(left, _PyFloat_ExactDealloc);
             _Py_DECREF_SPECIALIZED(right, _PyFloat_ExactDealloc);
             jump = sign_ish & when_to_jump_mask;
@@ -2057,8 +2055,8 @@ dummy_func(
             assert(Py_ABS(Py_SIZE(left)) <= 1 && Py_ABS(Py_SIZE(right)) <= 1);
             Py_ssize_t ileft = Py_SIZE(left) * ((PyLongObject *)left)->ob_digit[0];
             Py_ssize_t iright = Py_SIZE(right) * ((PyLongObject *)right)->ob_digit[0];
-            // 1 if <, 2 if ==, 4 if >; this matches when _to_jump_mask
-            int sign_ish = 2*(ileft > iright) + 2 - (ileft < iright);
+            // 2 if <, 4 if >, 8 if ==; this matches when_to_jump_mask
+            int sign_ish = 1 << (2 * (ileft >= iright) + (ileft <= iright));
             _Py_DECREF_SPECIALIZED(left, (destructor)PyObject_Free);
             _Py_DECREF_SPECIALIZED(right, (destructor)PyObject_Free);
             jump = sign_ish & when_to_jump_mask;

Python/generated_cases.c.h

@@ -1951,15 +1951,16 @@ compare_op_fail_kind(PyObject *lhs, PyObject *rhs)
 
 
 static int compare_masks[] = {
-    // 1-bit: jump if less than
-    // 2-bit: jump if equal
+    // 1-bit: jump if unordered
+    // 2-bit: jump if less
     // 4-bit: jump if greater
-    [Py_LT] = 1 | 0 | 0,
-    [Py_LE] = 1 | 2 | 0,
-    [Py_EQ] = 0 | 2 | 0,
-    [Py_NE] = 1 | 0 | 4,
-    [Py_GT] = 0 | 0 | 4,
-    [Py_GE] = 0 | 2 | 4,
+    // 8-bit: jump if equal
+    [Py_LT] = 0 | 2 | 0 | 0,
+    [Py_LE] = 0 | 2 | 0 | 8,
+    [Py_EQ] = 0 | 0 | 0 | 8,
+    [Py_NE] = 1 | 2 | 4 | 0,
+    [Py_GT] = 0 | 0 | 4 | 0,
+    [Py_GE] = 0 | 0 | 4 | 8,
 };
 
 void
@@ -1980,7 +1981,7 @@ _Py_Specialize_CompareOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
     assert(oparg <= Py_GE);
     int when_to_jump_mask = compare_masks[oparg];
     if (next_opcode == POP_JUMP_IF_FALSE) {
-        when_to_jump_mask = (1 | 2 | 4) & ~when_to_jump_mask;
+        when_to_jump_mask = (1 | 2 | 4 | 8) & ~when_to_jump_mask;
     }
     if (Py_TYPE(lhs) != Py_TYPE(rhs)) {
         SPECIALIZATION_FAIL(COMPARE_OP, compare_op_fail_kind(lhs, rhs));
@@ -2009,7 +2010,7 @@ _Py_Specialize_CompareOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
         }
         else {
             _py_set_opcode(instr, COMPARE_OP_STR_JUMP);
-            cache->mask = (when_to_jump_mask & 2) == 0;
+            cache->mask = (when_to_jump_mask & 8) == 0;
             goto success;
         }
     }