gh-114258: Update AC to support @critical_section for tp_iternext (gh-159962)

Author: corona10

Lib/test/test_clinic.py

@@ -15,14 +15,16 @@
 import re
 import sys
 import unittest
+from unittest import mock
 import warnings
 
 test_tools.skip_if_missing('clinic')
 with test_tools.imports_under_tool('clinic'):
     import libclinic
     from libclinic import ClinicError, unspecified, NULL, fail
     from libclinic.converters import (
-        int_converter, object_converter, str_converter, self_converter)
+        int_converter, object_converter, str_converter, self_converter,
+        Py_ssize_t_converter)
     from libclinic.function import (
         Module, Class, Function, FunctionKind, Parameter,
         permute_optional_groups, permute_right_option_groups,
@@ -34,6 +36,7 @@
     from libclinic.block_parser import Block, BlockParser
     from libclinic.codegen import BlockPrinter, Destination
     from libclinic.dsl_parser import DSLParser
+    from libclinic.slots import SlotSpec, SLOTS
     from libclinic.cli import parse_file, Clinic
 
 
@@ -807,6 +810,112 @@ def test_var_keyword_non_dict(self):
         """
         self.expect_failure(block, err, lineno=4)
 
+    def test_slot_next(self):
+        block = """
+            /*[clinic input]
+            output everything block
+            class Foo "FooObject *" "&Foo_Type"
+            [clinic start generated code]*/
+            /*[clinic input]
+            Foo.__next__
+            [clinic start generated code]*/
+            /*[clinic input]
+            @critical_section
+            Foo.__next__ as foo_iternext
+            [clinic start generated code]*/
+            #ifdef CONDITION
+            /*[clinic input]
+            Foo.__next__ as foo_iternext_cond
+            [clinic start generated code]*/
+            #endif
+        """
+        generated = self.clinic.parse(dedent(block))
+        self.assertIn(dedent("""
+            static PyObject *
+            Foo_next(PyObject *self)
+            {
+                return Foo_next_impl((FooObject *)self);
+            }
+        """), generated)
+        self.assertIn(dedent("""
+            static PyObject *
+            foo_iternext(PyObject *self)
+            {
+                PyObject *return_value = NULL;
+
+                Py_BEGIN_CRITICAL_SECTION(self);
+                return_value = foo_iternext_impl((FooObject *)self);
+                Py_END_CRITICAL_SECTION();
+
+                return return_value;
+            }
+        """), generated)
+        self.assertIn("#if defined(CONDITION)\n\nstatic PyObject *\n"
+                      "foo_iternext_cond_impl(FooObject *self);", generated)
+        # A slot function is not stored in a PyMethodDef.
+        for text in "METHODDEF", "PyDoc_", "#ifndef":
+            self.assertNotIn(text, generated)
+
+    def test_slot_with_parameters_and_return_type(self):
+        # Slots which take arguments or return something else than an
+        # object are not supported yet; check the machinery with fake ones.
+        slots = {
+            '__contains__': SlotSpec('__contains__', 'int', 'int',
+                                     {(object_converter,): 'sq_contains'}),
+            '__bool__': SlotSpec('__bool__', 'int', 'int', {(): 'nb_bool'}),
+        }
+        block = """
+            /*[clinic input]
+            output everything block
+            class Foo "FooObject *" "&Foo_Type"
+            [clinic start generated code]*/
+            /*[clinic input]
+            Foo.__contains__
+                value: object
+                /
+            [clinic start generated code]*/
+            /*[clinic input]
+            @critical_section
+            Foo.__bool__
+            [clinic start generated code]*/
+        """
+        with mock.patch.dict(SLOTS, slots):
+            generated = self.clinic.parse(dedent(block))
+        self.assertIn(dedent("""
+            static int
+            Foo_contains(PyObject *self, PyObject *value)
+            {
+                return Foo_contains_impl((FooObject *)self, value);
+            }
+        """), generated)
+        self.assertIn(dedent("""
+            static int
+            Foo_bool(PyObject *self)
+            {
+                int return_value = -1;
+
+                Py_BEGIN_CRITICAL_SECTION(self);
+                return_value = Foo_bool_impl((FooObject *)self);
+                Py_END_CRITICAL_SECTION();
+
+                return return_value;
+            }
+        """), generated)
+
+    def test_slot_cannot_be_cloned(self):
+        block = """
+            /*[clinic input]
+            class Foo "FooObject *" "&Foo_Type"
+            [clinic start generated code]*/
+            /*[clinic input]
+            Foo.__next__
+            [clinic start generated code]*/
+            /*[clinic input]
+            Foo.other = Foo.__next__
+            [clinic start generated code]*/
+        """
+        self.expect_failure(block, "Type slot methods cannot be cloned", lineno=8)
+
     def test_getset_in_ifdef(self):
         block = """
             /*[clinic input]
@@ -3237,6 +3346,78 @@ class Foo "" ""
                                   f"a normal callable")
                 self.expect_failure(block, expected_error, lineno=3)
 
+    def test_slot_next(self):
+        function = self.parse_function("""
+            module foo
+            class Foo "FooObject *" ""
+            Foo.__next__
+        """, signatures_in_block=3, function_index=2)
+        self.assertIs(function.kind, FunctionKind.SLOT)
+        self.assertEqual(function.slot.name, "__next__")
+        self.assertEqual(function.c_basename, "Foo_next")
+        self.assertEqual(function.return_converter.type, "PyObject *")
+        self.assertEqual(list(function.parameters), ["self"])
+
+    def test_slot_parameters(self):
+        slot = SlotSpec('__contains__', 'int', 'int', {
+            (Py_ssize_t_converter,): 'sq_fake',
+            (object_converter,): 'sq_contains'})
+        block = """
+            module foo
+            class Foo "FooObject *" ""
+            Foo.__contains__
+                value: {converter}
+                /
+        """
+        errors = [
+            ("Foo.__contains__",
+             "'__contains__' must declare (Py_ssize_t) for sq_fake or "
+             "(object) for sq_contains; got ()"),
+            ("Foo.__contains__\n    value: int\n    /",
+             "'__contains__' must declare"),
+            ("Foo.__contains__\n    value: object",
+             "The parameters of '__contains__' must be positional-only"),
+            ("Foo.__contains__\n    value: object = None\n    /",
+             "The parameters of '__contains__' cannot have a default value"),
+        ]
+        with mock.patch.dict(SLOTS, {'__contains__': slot}):
+            for converter in "Py_ssize_t", "object":
+                with self.subTest(converter=converter):
+                    function = self.parse_function(
+                        block.format(converter=converter),
+                        signatures_in_block=3, function_index=2)
+                    self.assertIs(function.kind, FunctionKind.SLOT)
+                    self.assertEqual(function.return_converter.type, "int")
+                    self.assertEqual(list(function.parameters), ["self", "value"])
+            for body, err in errors:
+                with self.subTest(block=body):
+                    body = 'class Foo "FooObject *" "&Foo_Type"\n' + body
+                    self.expect_failure(body, err)
+
+    def test_slot_errors(self):
+        cases = [
+            ("module foo\nfoo.__next__",
+             "'__next__' must be a method!"),
+            ("@classmethod\nFoo.__next__",
+             "'__next__' must be a normal method"),
+            ("@getter\nFoo.__next__",
+             "'__next__' must be a normal method"),
+            ("@coexist\nFoo.__next__",
+             "@coexist cannot be applied to '__next__'"),
+            ("@vectorcall\nFoo.__next__",
+             "@vectorcall can only be used with __init__ and __new__"),
+            ("Foo.__next__\n    a: int",
+             "'__next__' methods cannot define parameters"),
+            ("Foo.__next__ -> int",
+             "'Foo.__next__' cannot define a return type"),
+            ("Foo.__next__\n\nReturn the next item.",
+             "'__next__' methods cannot have a docstring"),
+        ]
+        for block, err in cases:
+            with self.subTest(block=block):
+                block = 'class Foo "FooObject *" "&Foo_Type"\n' + block
+                self.expect_failure(block, err)
+
     def test_deleter_without_setter(self):
         block = """
             module foo

Misc/NEWS.d/next/Tools-Demos/2026-10-20-12-50-00.gh-issue-114258.slotNx.rst

@@ -0,0 +1,3 @@
+Argument Clinic now supports the ``__next__`` type slot (``tp_iternext``),
+including ``@critical_section``.
+

Modules/_csv.c

@@ -22,8 +22,9 @@ module instead.
 /*[clinic input]
 module _csv
 class _csv.Dialect "DialectObj *" "clinic_state()->dialect_type"
+class _csv.Reader "ReaderObj *" "clinic_state()->reader_type"
 [clinic start generated code]*/
-/*[clinic end generated code: output=da39a3ee5e6b4b0d input=042fcc14c7d541cc]*/
+/*[clinic end generated code: output=da39a3ee5e6b4b0d input=7bdf66dc7d68ed90]*/
 #define NOT_SET ((Py_UCS4)-1)
 #define EOL ((Py_UCS4)-2)
 
@@ -124,8 +125,6 @@ typedef struct {
     bool nonascii_special;
 } DialectObj;
 
-#include "clinic/_csv.c.h"
-
 typedef struct {
     PyObject_HEAD
 
@@ -161,6 +160,8 @@ typedef struct {
 #define _ReaderObj_CAST(op)     ((ReaderObj *)(op))
 #define _WriterObj_CAST(op)     ((WriterObj *)(op))
 
+#include "clinic/_csv.c.h"
+
 /*
  * DIALECT class
  */
@@ -1020,11 +1021,15 @@ parse_reset(ReaderObj *self)
     return 0;
 }
 
+/*[clinic input]
+@critical_section
+_csv.Reader.__next__ as Reader_iternext
+[clinic start generated code]*/
+
 static PyObject *
-Reader_iternext_lock_held(PyObject *op)
+Reader_iternext_impl(ReaderObj *self)
+/*[clinic end generated code: output=3a02b0254a76e1fc input=97c70a4e2fe621e4]*/
 {
-    ReaderObj *self = _ReaderObj_CAST(op);
-
     PyObject *fields = NULL;
     Py_UCS4 c;
     Py_ssize_t pos, linelen;
@@ -1094,16 +1099,6 @@ Reader_iternext_lock_held(PyObject *op)
     return fields;
 }
 
-static PyObject *
-Reader_iternext(PyObject *op)
-{
-    PyObject *result;
-    Py_BEGIN_CRITICAL_SECTION(op);
-    result = Reader_iternext_lock_held(op);
-    Py_END_CRITICAL_SECTION();
-    return result;
-}
-
 static void
 Reader_dealloc(PyObject *op)
 {

Modules/_io/bytesio.c

@@ -768,13 +768,18 @@ _io_BytesIO_truncate_impl(bytesio *self, PyObject *size)
     return PyLong_FromSsize_t(new_size);
 }
 
+/*[clinic input]
+@critical_section
+_io.BytesIO.__next__ as bytesio_iternext
+[clinic start generated code]*/
+
 static PyObject *
-bytesio_iternext_lock_held(PyObject *op)
+bytesio_iternext_impl(bytesio *self)
+/*[clinic end generated code: output=f530bdee3a720d48 input=7fb3a763efe11a21]*/
 {
-    _Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(op);
+    _Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(self);
 
     Py_ssize_t n;
-    bytesio *self = bytesio_CAST(op);
 
     CHECK_CLOSED(self);
 
@@ -786,16 +791,6 @@ bytesio_iternext_lock_held(PyObject *op)
     return read_bytes_lock_held(self, n);
 }
 
-static PyObject *
-bytesio_iternext(PyObject *op)
-{
-    PyObject *ret;
-    Py_BEGIN_CRITICAL_SECTION(op);
-    ret = bytesio_iternext_lock_held(op);
-    Py_END_CRITICAL_SECTION();
-    return ret;
-}
-
 /*[clinic input]
 @critical_section
 _io.BytesIO.seek