Apr 28, 2025 · Apr 25, 2025 · Apr 26, 2025 · Apr 26, 2025 · Apr 26, 2025 · Apr 26, 2025
diff --git a/Include/internal/pycore_global_objects_fini_generated.h b/Include/internal/pycore_global_objects_fini_generated.h
diff --git a/Include/internal/pycore_global_strings.h b/Include/internal/pycore_global_strings.h
        STRUCT_FOR_ID(intern)
        STRUCT_FOR_ID(intersection)
        STRUCT_FOR_ID(interval)
        STRUCT_FOR_ID(io)
        STRUCT_FOR_ID(is_running)
        STRUCT_FOR_ID(is_struct)
        STRUCT_FOR_ID(isatty)
diff --git a/Include/internal/pycore_runtime_init_generated.h b/Include/internal/pycore_runtime_init_generated.h
diff --git a/Include/internal/pycore_unicodeobject_generated.h b/Include/internal/pycore_unicodeobject_generated.h
diff --git a/Lib/io.py b/Lib/io.py
                 IncrementalNewlineDecoder, text_encoding, TextIOWrapper)


 # Pretend this exception was created here.
 UnsupportedOperation.__module__ = "io"

 # for seek()
 SEEK_SET = 0
 SEEK_CUR = 1
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
            self.assertRaises(exc, fp.seek, 1, self.SEEK_CUR)
            self.assertRaises(exc, fp.seek, -1, self.SEEK_END)

    @support.cpython_only
    def test_startup_optimization(self):
        # gh-132952: Test that `io` is not imported at startup and that the
        # __module__ of UnsupportedOperation is set to "io".
        assert_python_ok("-S", "-c", textwrap.dedent(
            """
            import sys
            assert "io" not in sys.modules
            try:
                sys.stdin.truncate()
            except Exception as e:
                typ = type(e)
                assert typ.__module__ == "io", (typ, typ.__module__)
                assert typ.__name__ == "UnsupportedOperation", (typ, typ.__name__)
            else:
                raise AssertionError("Expected UnsupportedOperation")
            """
        ))

    @unittest.skipUnless(hasattr(os, "pipe"), "requires os.pipe()")
    def test_optional_abilities(self):
        # Test for OSError when optional APIs are not supported
diff --git a/Modules/_io/_iomodule.c b/Modules/_io/_iomodule.c
        "UnsupportedOperation", PyExc_OSError, PyExc_ValueError);
    if (state->unsupported_operation == NULL)
        return -1;
    if (PyObject_SetAttrString(state->unsupported_operation,
                               "__module__", &_Py_ID(io)) < 0)
    {
        return -1;
    }
    if (PyModule_AddObjectRef(m, "UnsupportedOperation",
                              state->unsupported_operation) < 0)
    {
Original file line number	Diff line number	Diff line change
Expand Up		@@ -514,6 +514,7 @@ struct _Py_global_strings {
		STRUCT_FOR_ID(intern)
		STRUCT_FOR_ID(intersection)
		STRUCT_FOR_ID(interval)
		STRUCT_FOR_ID(io)
		STRUCT_FOR_ID(is_running)
		STRUCT_FOR_ID(is_struct)
		STRUCT_FOR_ID(isatty)
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -60,9 +60,6 @@
		IncrementalNewlineDecoder, text_encoding, TextIOWrapper)


		# Pretend this exception was created here.
		UnsupportedOperation.__module__ = "io"

		# for seek()
		SEEK_SET = 0
		SEEK_CUR = 1
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -445,6 +445,25 @@ def test_invalid_operations(self):
		self.assertRaises(exc, fp.seek, 1, self.SEEK_CUR)
		self.assertRaises(exc, fp.seek, -1, self.SEEK_END)

		@support.cpython_only
		def test_startup_optimization(self):
		# gh-132952: Test that `io` is not imported at startup and that the
		# __module__ of UnsupportedOperation is set to "io".
		assert_python_ok("-S", "-c", textwrap.dedent(
		"""
		import sys
		assert "io" not in sys.modules
		try:
		sys.stdin.truncate()
		except Exception as e:
		typ = type(e)
		assert typ.__module__ == "io", (typ, typ.__module__)
		assert typ.__name__ == "UnsupportedOperation", (typ, typ.__name__)
		else:
		raise AssertionError("Expected UnsupportedOperation")
		"""
		))

		@unittest.skipUnless(hasattr(os, "pipe"), "requires os.pipe()")
		def test_optional_abilities(self):
		# Test for OSError when optional APIs are not supported
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -661,6 +661,11 @@ iomodule_exec(PyObject *m)
		"UnsupportedOperation", PyExc_OSError, PyExc_ValueError);
		if (state->unsupported_operation == NULL)
		return -1;
		if (PyObject_SetAttrString(state->unsupported_operation,
		"__module__", &_Py_ID(io)) < 0)
		{
		return -1;
		}
		if (PyModule_AddObjectRef(m, "UnsupportedOperation",
		state->unsupported_operation) < 0)
		{
Expand Down