Use return converters and a typed setter value for _io accessors

The getters which return a boolean or an integer now use the bool, long and Py_ssize_t return converters, and the TextIOWrapper._CHUNK_SIZE setter declares its value as Py_ssize_t. An out of range _CHUNK_SIZE now raises OverflowError instead of ValueError.
serhiy-storchaka · Sep 24, 2026 · Aug 10, 2026 · Aug 13, 2026 · Aug 13, 2026 · Aug 13, 2026
commit 07dfaaa63e46559d2c8674d99ee5d6f530919484
diff --git a/Lib/test/test_io/test_textio.py b/Lib/test/test_io/test_textio.py
@@ -1458,13 +1458,13 @@ def test_chunk_size(self):
             t._CHUNK_SIZE = 0
         with self.assertRaises(TypeError):
             t._CHUNK_SIZE = 'x'
-        with self.assertRaises(ValueError):
+        with self.assertRaises(OverflowError):
             t._CHUNK_SIZE = sys.maxsize + 1
-        with self.assertRaises(ValueError):
+        with self.assertRaises(OverflowError):
             t._CHUNK_SIZE = -sys.maxsize - 2
-        with self.assertRaises(ValueError):
+        with self.assertRaises(OverflowError):
             t._CHUNK_SIZE = 2**1000
-        with self.assertRaises(ValueError):
+        with self.assertRaises(OverflowError):
             t._CHUNK_SIZE = -2**1000
         with self.assertRaisesRegex(AttributeError, 'cannot be deleted'):
             del t._CHUNK_SIZE

diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
@@ -300,16 +300,16 @@ write_bytes_lock_held(bytesio *self, PyObject *b)
 /*[clinic input]
 @critical_section
 @getter
-_io.BytesIO.closed
+_io.BytesIO.closed -> bool
 
 True if the file is closed.
 [clinic start generated code]*/
 
-static PyObject *
+static int
 _io_BytesIO_closed_get_impl(bytesio *self)
-/*[clinic end generated code: output=3210245d480df846 input=53d116fdfe4e7580]*/
+/*[clinic end generated code: output=7cdc647cc7a71683 input=0687f923344225ee]*/
 {
-    return PyBool_FromLong(self->buf == NULL);
+    return self->buf == NULL;
 }
 
 /*[clinic input]

diff --git a/Modules/_io/clinic/bytesio.c.h b/Modules/_io/clinic/bytesio.c.h
diff --git a/Modules/_io/clinic/fileio.c.h b/Modules/_io/clinic/fileio.c.h
diff --git a/Modules/_io/clinic/iobase.c.h b/Modules/_io/clinic/iobase.c.h
diff --git a/Modules/_io/clinic/stringio.c.h b/Modules/_io/clinic/stringio.c.h
diff --git a/Modules/_io/clinic/textio.c.h b/Modules/_io/clinic/textio.c.h
diff --git a/Modules/_io/clinic/winconsoleio.c.h b/Modules/_io/clinic/winconsoleio.c.h