bpo-46765: Replace Locally Cached Strings with Statically Initialized Objects (gh-31366)

https://bugs.python.org/issue46765

6 files changed, 69 insertions, 211 deletions

diff --git a/Modules/_io/_iomodule.c b/Modules/_io/_iomodule.c
index 9ecc671..7f029f2 100644
--- a/Modules/_io/_iomodule.c
+++ b/Modules/_io/_iomodule.c
@@ -24,38 +24,6 @@
 #include <windows.h>
 #endif
 
-/* Various interned strings */
-
-PyObject *_PyIO_str_close = NULL;
-PyObject *_PyIO_str_closed = NULL;
-PyObject *_PyIO_str_decode = NULL;
-PyObject *_PyIO_str_encode = NULL;
-PyObject *_PyIO_str_fileno = NULL;
-PyObject *_PyIO_str_flush = NULL;
-PyObject *_PyIO_str_getstate = NULL;
-PyObject *_PyIO_str_isatty = NULL;
-PyObject *_PyIO_str_locale = NULL;
-PyObject *_PyIO_str_newlines = NULL;
-PyObject *_PyIO_str_nl = NULL;
-PyObject *_PyIO_str_peek = NULL;
-PyObject *_PyIO_str_read = NULL;
-PyObject *_PyIO_str_read1 = NULL;
-PyObject *_PyIO_str_readable = NULL;
-PyObject *_PyIO_str_readall = NULL;
-PyObject *_PyIO_str_readinto = NULL;
-PyObject *_PyIO_str_readline = NULL;
-PyObject *_PyIO_str_reset = NULL;
-PyObject *_PyIO_str_seek = NULL;
-PyObject *_PyIO_str_seekable = NULL;
-PyObject *_PyIO_str_setstate = NULL;
-PyObject *_PyIO_str_tell = NULL;
-PyObject *_PyIO_str_truncate = NULL;
-PyObject *_PyIO_str_writable = NULL;
-PyObject *_PyIO_str_write = NULL;
-
-PyObject *_PyIO_empty_str = NULL;
-PyObject *_PyIO_empty_bytes = NULL;
-
 PyDoc_STRVAR(module_doc,
 "The io module provides the Python interfaces to stream handling. The\n"
 "builtin open function is defined in this module.\n"
@@ -511,8 +479,7 @@ _io_text_encoding_impl(PyObject *module, PyObject *encoding, int stacklevel)
                 return NULL;
             }
         }
-        Py_INCREF(_PyIO_str_locale);
-        return _PyIO_str_locale;
+        return &_Py_ID(locale);
     }
     Py_INCREF(encoding);
     return encoding;
@@ -699,41 +666,6 @@ _PyIO_Fini(void)
         PyTypeObject *exc = static_types[i];
         _PyStaticType_Dealloc(exc);
     }
-
-    /* Interned strings */
-#define CLEAR_INTERNED(name) \
-    Py_CLEAR(_PyIO_str_ ## name)
-
-    CLEAR_INTERNED(close);
-    CLEAR_INTERNED(closed);
-    CLEAR_INTERNED(decode);
-    CLEAR_INTERNED(encode);
-    CLEAR_INTERNED(fileno);
-    CLEAR_INTERNED(flush);
-    CLEAR_INTERNED(getstate);
-    CLEAR_INTERNED(isatty);
-    CLEAR_INTERNED(locale);
-    CLEAR_INTERNED(newlines);
-    CLEAR_INTERNED(peek);
-    CLEAR_INTERNED(read);
-    CLEAR_INTERNED(read1);
-    CLEAR_INTERNED(readable);
-    CLEAR_INTERNED(readall);
-    CLEAR_INTERNED(readinto);
-    CLEAR_INTERNED(readline);
-    CLEAR_INTERNED(reset);
-    CLEAR_INTERNED(seek);
-    CLEAR_INTERNED(seekable);
-    CLEAR_INTERNED(setstate);
-    CLEAR_INTERNED(tell);
-    CLEAR_INTERNED(truncate);
-    CLEAR_INTERNED(write);
-    CLEAR_INTERNED(writable);
-#undef CLEAR_INTERNED
-
-    Py_CLEAR(_PyIO_str_nl);
-    Py_CLEAR(_PyIO_empty_str);
-    Py_CLEAR(_PyIO_empty_bytes);
 }
 
 
@@ -797,50 +729,6 @@ PyInit__io(void)
         }
     }
 
-    /* Interned strings */
-#define ADD_INTERNED(name) \
-    if (!_PyIO_str_ ## name && \
-        !(_PyIO_str_ ## name = PyUnicode_InternFromString(# name))) \
-        goto fail;
-
-    ADD_INTERNED(close)
-    ADD_INTERNED(closed)
-    ADD_INTERNED(decode)
-    ADD_INTERNED(encode)
-    ADD_INTERNED(fileno)
-    ADD_INTERNED(flush)
-    ADD_INTERNED(getstate)
-    ADD_INTERNED(isatty)
-    ADD_INTERNED(locale)
-    ADD_INTERNED(newlines)
-    ADD_INTERNED(peek)
-    ADD_INTERNED(read)
-    ADD_INTERNED(read1)
-    ADD_INTERNED(readable)
-    ADD_INTERNED(readall)
-    ADD_INTERNED(readinto)
-    ADD_INTERNED(readline)
-    ADD_INTERNED(reset)
-    ADD_INTERNED(seek)
-    ADD_INTERNED(seekable)
-    ADD_INTERNED(setstate)
-    ADD_INTERNED(tell)
-    ADD_INTERNED(truncate)
-    ADD_INTERNED(write)
-    ADD_INTERNED(writable)
-#undef ADD_INTERNED
-
-    if (!_PyIO_str_nl &&
-        !(_PyIO_str_nl = PyUnicode_InternFromString("\n")))
-        goto fail;
-
-    if (!_PyIO_empty_str &&
-        !(_PyIO_empty_str = PyUnicode_FromStringAndSize(NULL, 0)))
-        goto fail;
-    if (!_PyIO_empty_bytes &&
-        !(_PyIO_empty_bytes = PyBytes_FromStringAndSize(NULL, 0)))
-        goto fail;
-
     state->initialized = 1;
 
     return m;
diff --git a/Modules/_io/_iomodule.h b/Modules/_io/_iomodule.h
index 638797f..c260080 100644
--- a/Modules/_io/_iomodule.h
+++ b/Modules/_io/_iomodule.h
@@ -155,33 +155,4 @@ extern _PyIO_State *_PyIO_get_module_state(void);
 extern char _PyIO_get_console_type(PyObject *);
 #endif
 
-extern PyObject *_PyIO_str_close;
-extern PyObject *_PyIO_str_closed;
-extern PyObject *_PyIO_str_decode;
-extern PyObject *_PyIO_str_encode;
-extern PyObject *_PyIO_str_fileno;
-extern PyObject *_PyIO_str_flush;
-extern PyObject *_PyIO_str_getstate;
-extern PyObject *_PyIO_str_isatty;
-extern PyObject *_PyIO_str_newlines;
-extern PyObject *_PyIO_str_nl;
-extern PyObject *_PyIO_str_peek;
-extern PyObject *_PyIO_str_read;
-extern PyObject *_PyIO_str_read1;
-extern PyObject *_PyIO_str_readable;
-extern PyObject *_PyIO_str_readall;
-extern PyObject *_PyIO_str_readinto;
-extern PyObject *_PyIO_str_readline;
-extern PyObject *_PyIO_str_reset;
-extern PyObject *_PyIO_str_seek;
-extern PyObject *_PyIO_str_seekable;
-extern PyObject *_PyIO_str_setstate;
-extern PyObject *_PyIO_str_tell;
-extern PyObject *_PyIO_str_truncate;
-extern PyObject *_PyIO_str_writable;
-extern PyObject *_PyIO_str_write;
-
-extern PyObject *_PyIO_empty_str;
-extern PyObject *_PyIO_empty_bytes;
-
 extern Py_EXPORTED_SYMBOL PyTypeObject _PyBytesIOBuffer_Type;
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index bb93ae3..ac30d1d 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -443,7 +443,7 @@ static PyObject *
 buffered_simple_flush(buffered *self, PyObject *args)
 {
     CHECK_INITIALIZED(self)
-    return PyObject_CallMethodNoArgs(self->raw, _PyIO_str_flush);
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(flush));
 }
 
 static int
@@ -452,7 +452,7 @@ buffered_closed(buffered *self)
     int closed;
     PyObject *res;
     CHECK_INITIALIZED_INT(self)
-    res = PyObject_GetAttr(self->raw, _PyIO_str_closed);
+    res = PyObject_GetAttr(self->raw, &_Py_ID(closed));
     if (res == NULL)
         return -1;
     closed = PyObject_IsTrue(res);
@@ -464,7 +464,7 @@ static PyObject *
 buffered_closed_get(buffered *self, void *context)
 {
     CHECK_INITIALIZED(self)
-    return PyObject_GetAttr(self->raw, _PyIO_str_closed);
+    return PyObject_GetAttr(self->raw, &_Py_ID(closed));
 }
 
 static PyObject *
@@ -495,7 +495,7 @@ buffered_close(buffered *self, PyObject *args)
     }
     /* flush() will most probably re-take the lock, so drop it first */
     LEAVE_BUFFERED(self)
-    res = PyObject_CallMethodNoArgs((PyObject *)self, _PyIO_str_flush);
+    res = PyObject_CallMethodNoArgs((PyObject *)self, &_Py_ID(flush));
     if (!ENTER_BUFFERED(self))
         return NULL;
     if (res == NULL)
@@ -503,7 +503,7 @@ buffered_close(buffered *self, PyObject *args)
     else
         Py_DECREF(res);
 
-    res = PyObject_CallMethodNoArgs(self->raw, _PyIO_str_close);
+    res = PyObject_CallMethodNoArgs(self->raw, &_Py_ID(close));
 
     if (self->buffer) {
         PyMem_Free(self->buffer);
@@ -530,7 +530,7 @@ buffered_detach(buffered *self, PyObject *Py_UNUSED(ignored))
 {
     PyObject *raw, *res;
     CHECK_INITIALIZED(self)
-    res = PyObject_CallMethodNoArgs((PyObject *)self, _PyIO_str_flush);
+    res = PyObject_CallMethodNoArgs((PyObject *)self, &_Py_ID(flush));
     if (res == NULL)
         return NULL;
     Py_DECREF(res);
@@ -547,21 +547,21 @@ static PyObject *
 buffered_seekable(buffered *self, PyObject *Py_UNUSED(ignored))
 {
     CHECK_INITIALIZED(self)
-    return PyObject_CallMethodNoArgs(self->raw, _PyIO_str_seekable);
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(seekable));
 }
 
 static PyObject *
 buffered_readable(buffered *self, PyObject *Py_UNUSED(ignored))
 {
     CHECK_INITIALIZED(self)
-    return PyObject_CallMethodNoArgs(self->raw, _PyIO_str_readable);
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(readable));
 }
 
 static PyObject *
 buffered_writable(buffered *self, PyObject *Py_UNUSED(ignored))
 {
     CHECK_INITIALIZED(self)
-    return PyObject_CallMethodNoArgs(self->raw, _PyIO_str_writable);
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(writable));
 }
 
 static PyObject *
@@ -584,14 +584,14 @@ static PyObject *
 buffered_fileno(buffered *self, PyObject *Py_UNUSED(ignored))
 {
     CHECK_INITIALIZED(self)
-    return PyObject_CallMethodNoArgs(self->raw, _PyIO_str_fileno);
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(fileno));
 }
 
 static PyObject *
 buffered_isatty(buffered *self, PyObject *Py_UNUSED(ignored))
 {
     CHECK_INITIALIZED(self)
-    return PyObject_CallMethodNoArgs(self->raw, _PyIO_str_isatty);
+    return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(isatty));
 }
 
 /* Forward decls */
@@ -655,7 +655,7 @@ _buffered_raw_tell(buffered *self)
 {
     Py_off_t n;
     PyObject *res;
-    res = PyObject_CallMethodNoArgs(self->raw, _PyIO_str_tell);
+    res = PyObject_CallMethodNoArgs(self->raw, &_Py_ID(tell));
     if (res == NULL)
         return -1;
     n = PyNumber_AsOff_t(res, PyExc_ValueError);
@@ -685,7 +685,7 @@ _buffered_raw_seek(buffered *self, Py_off_t target, int whence)
         Py_DECREF(posobj);
         return -1;
     }
-    res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_seek,
+    res = PyObject_CallMethodObjArgs(self->raw, &_Py_ID(seek),
                                      posobj, whenceobj, NULL);
     Py_DECREF(posobj);
     Py_DECREF(whenceobj);
@@ -1152,7 +1152,7 @@ found:
         Py_CLEAR(res);
         goto end;
     }
-    Py_XSETREF(res, _PyBytes_Join(_PyIO_empty_bytes, chunks));
+    Py_XSETREF(res, _PyBytes_Join((PyObject *)&_Py_SINGLETON(bytes_empty), chunks));
 
 end:
     LEAVE_BUFFERED(self)
@@ -1311,7 +1311,7 @@ _io__Buffered_truncate_impl(buffered *self, PyObject *pos)
     }
     Py_CLEAR(res);
 
-    res = PyObject_CallMethodOneArg(self->raw, _PyIO_str_truncate, pos);
+    res = PyObject_CallMethodOneArg(self->raw, &_Py_ID(truncate), pos);
     if (res == NULL)
         goto end;
     /* Reset cached position */
@@ -1339,7 +1339,7 @@ buffered_iternext(buffered *self)
     }
     else {
         line = PyObject_CallMethodNoArgs((PyObject *)self,
-                                             _PyIO_str_readline);
+                                             &_Py_ID(readline));
         if (line && !PyBytes_Check(line)) {
             PyErr_Format(PyExc_OSError,
                          "readline() should have returned a bytes object, "
@@ -1457,7 +1457,7 @@ _bufferedreader_raw_read(buffered *self, char *start, Py_ssize_t len)
        raised (see issue #10956).
     */
     do {
-        res = PyObject_CallMethodOneArg(self->raw, _PyIO_str_readinto, memobj);
+        res = PyObject_CallMethodOneArg(self->raw, &_Py_ID(readinto), memobj);
     } while (res == NULL && _PyIO_trap_eintr());
     Py_DECREF(memobj);
     if (res == NULL)
@@ -1530,7 +1530,7 @@ _bufferedreader_read_all(buffered *self)
     }
     _bufferedreader_reset_buf(self);
 
-    if (_PyObject_LookupAttr(self->raw, _PyIO_str_readall, &readall) < 0) {
+    if (_PyObject_LookupAttr(self->raw, &_Py_ID(readall), &readall) < 0) {
         goto cleanup;
     }
     if (readall) {
@@ -1565,7 +1565,7 @@ _bufferedreader_read_all(buffered *self)
         }
 
         /* Read until EOF or until read() would block. */
-        data = PyObject_CallMethodNoArgs(self->raw, _PyIO_str_read);
+        data = PyObject_CallMethodNoArgs(self->raw, &_Py_ID(read));
         if (data == NULL)
             goto cleanup;
         if (data != Py_None && !PyBytes_Check(data)) {
@@ -1578,7 +1578,7 @@ _bufferedreader_read_all(buffered *self)
                 goto cleanup;
             }
             else {
-                tmp = _PyBytes_Join(_PyIO_empty_bytes, chunks);
+                tmp = _PyBytes_Join((PyObject *)&_Py_SINGLETON(bytes_empty), chunks);
                 res = tmp;
                 goto cleanup;
             }
@@ -1814,7 +1814,7 @@ _bufferedwriter_raw_write(buffered *self, char *start, Py_ssize_t len)
     */
     do {
         errno = 0;
-        res = PyObject_CallMethodOneArg(self->raw, _PyIO_str_write, memobj);
+        res = PyObject_CallMethodOneArg(self->raw, &_Py_ID(write), memobj);
         errnum = errno;
     } while (res == NULL && _PyIO_trap_eintr());
     Py_DECREF(memobj);
@@ -2251,7 +2251,7 @@ bufferedrwpair_closed_get(rwpair *self, void *context)
                 "the BufferedRWPair object is being garbage-collected");
         return NULL;
     }
-    return PyObject_GetAttr((PyObject *) self->writer, _PyIO_str_closed);
+    return PyObject_GetAttr((PyObject *) self->writer, &_Py_ID(closed));
 }
 
 
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index 74663e0..b00b6b9 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -181,7 +181,7 @@ iobase_check_closed(PyObject *self)
     int closed;
     /* This gets the derived attribute, which is *not* __IOBase_closed
        in most cases! */
-    closed = _PyObject_LookupAttr(self, _PyIO_str_closed, &res);
+    closed = _PyObject_LookupAttr(self, &_Py_ID(closed), &res);
     if (closed > 0) {
         closed = PyObject_IsTrue(res);
         Py_DECREF(res);
@@ -231,7 +231,7 @@ _io__IOBase_close_impl(PyObject *self)
         Py_RETURN_NONE;
     }
 
-    res = PyObject_CallMethodNoArgs(self, _PyIO_str_flush);
+    res = PyObject_CallMethodNoArgs(self, &_Py_ID(flush));
 
     PyErr_Fetch(&exc, &val, &tb);
     rc = PyObject_SetAttr(self, &_Py_ID(__IOBase_closed), Py_True);
@@ -261,7 +261,7 @@ iobase_finalize(PyObject *self)
 
     /* If `closed` doesn't exist or can't be evaluated as bool, then the
        object is probably in an unusable state, so ignore. */
-    if (_PyObject_LookupAttr(self, _PyIO_str_closed, &res) <= 0) {
+    if (_PyObject_LookupAttr(self, &_Py_ID(closed), &res) <= 0) {
         PyErr_Clear();
         closed = -1;
     }
@@ -276,7 +276,7 @@ iobase_finalize(PyObject *self)
            finalization process. */
         if (PyObject_SetAttr(self, &_Py_ID(_finalizing), Py_True))
             PyErr_Clear();
-        res = PyObject_CallMethodNoArgs((PyObject *)self, _PyIO_str_close);
+        res = PyObject_CallMethodNoArgs((PyObject *)self, &_Py_ID(close));
         /* Silencing I/O errors is bad, but printing spurious tracebacks is
            equally as bad, and potentially more frequent (because of
            shutdown issues). */
@@ -377,7 +377,7 @@ _io__IOBase_seekable_impl(PyObject *self)
 PyObject *
 _PyIOBase_check_seekable(PyObject *self, PyObject *args)
 {
-    PyObject *res  = PyObject_CallMethodNoArgs(self, _PyIO_str_seekable);
+    PyObject *res  = PyObject_CallMethodNoArgs(self, &_Py_ID(seekable));
     if (res == NULL)
         return NULL;
     if (res != Py_True) {
@@ -410,7 +410,7 @@ _io__IOBase_readable_impl(PyObject *self)
 PyObject *
 _PyIOBase_check_readable(PyObject *self, PyObject *args)
 {
-    PyObject *res = PyObject_CallMethodNoArgs(self, _PyIO_str_readable);
+    PyObject *res = PyObject_CallMethodNoArgs(self, &_Py_ID(readable));
     if (res == NULL)
         return NULL;
     if (res != Py_True) {
@@ -443,7 +443,7 @@ _io__IOBase_writable_impl(PyObject *self)
 PyObject *
 _PyIOBase_check_writable(PyObject *self, PyObject *args)
 {
-    PyObject *res = PyObject_CallMethodNoArgs(self, _PyIO_str_writable);
+    PyObject *res = PyObject_CallMethodNoArgs(self, &_Py_ID(writable));
     if (res == NULL)
         return NULL;
     if (res != Py_True) {
@@ -472,7 +472,7 @@ iobase_enter(PyObject *self, PyObject *args)
 static PyObject *
 iobase_exit(PyObject *self, PyObject *args)
 {
-    return PyObject_CallMethodNoArgs(self, _PyIO_str_close);
+    return PyObject_CallMethodNoArgs(self, &_Py_ID(close));
 }
 
 /* Lower-level APIs */
@@ -536,7 +536,7 @@ _io__IOBase_readline_impl(PyObject *self, Py_ssize_t limit)
     PyObject *peek, *buffer, *result;
     Py_ssize_t old_size = -1;
 
-    if (_PyObject_LookupAttr(self, _PyIO_str_peek, &peek) < 0) {
+    if (_PyObject_LookupAttr(self, &_Py_ID(peek), &peek) < 0) {
         return NULL;
     }
 
@@ -650,7 +650,7 @@ iobase_iter(PyObject *self)
 static PyObject *
 iobase_iternext(PyObject *self)
 {
-    PyObject *line = PyObject_CallMethodNoArgs(self, _PyIO_str_readline);
+    PyObject *line = PyObject_CallMethodNoArgs(self, &_Py_ID(readline));
 
     if (line == NULL)
         return NULL;
@@ -776,7 +776,7 @@ _io__IOBase_writelines(PyObject *self, PyObject *lines)
 
         res = NULL;
         do {
-            res = PyObject_CallMethodObjArgs(self, _PyIO_str_write, line, NULL);
+            res = PyObject_CallMethodObjArgs(self, &_Py_ID(write), line, NULL);
         } while (res == NULL && _PyIO_trap_eintr());
         Py_DECREF(line);
         if (res == NULL) {
@@ -920,7 +920,7 @@ _io__RawIOBase_read_impl(PyObject *self, Py_ssize_t n)
     if (b == NULL)
         return NULL;
 
-    res = PyObject_CallMethodObjArgs(self, _PyIO_str_readinto, b, NULL);
+    res = PyObject_CallMethodObjArgs(self, &_Py_ID(readinto), b, NULL);
     if (res == NULL || res == Py_None) {
         Py_DECREF(b);
         return res;
@@ -994,7 +994,7 @@ _io__RawIOBase_readall_impl(PyObject *self)
             return NULL;
         }
     }
-    result = _PyBytes_Join(_PyIO_empty_bytes, chunks);
+    result = _PyBytes_Join((PyObject *)&_Py_SINGLETON(bytes_empty), chunks);
     Py_DECREF(chunks);
     return result;
 }
diff --git a/Modules/_io/stringio.c b/Modules/_io/stringio.c
index e76152e..3fe02d3 100644
--- a/Modules/_io/stringio.c
+++ b/Modules/_io/stringio.c
@@ -192,7 +192,7 @@ write_str(stringio *self, PyObject *obj)
     }
     if (self->writenl) {
         PyObject *translated = PyUnicode_Replace(
-            decoded, _PyIO_str_nl, self->writenl, -1);
+            decoded, &_Py_STR(newline), self->writenl, -1);
         Py_DECREF(decoded);
         decoded = translated;
     }
@@ -409,7 +409,7 @@ stringio_iternext(stringio *self)
     else {
         /* XXX is subclassing StringIO really supported? */
         line = PyObject_CallMethodNoArgs((PyObject *)self,
-                                             _PyIO_str_readline);
+                                             &_Py_ID(readline));
         if (line && !PyUnicode_Check(line)) {
             PyErr_Format(PyExc_OSError,
                          "readline() should have returned a str object, "
@@ -964,7 +964,7 @@ stringio_newlines(stringio *self, void *context)
     CHECK_CLOSED(self);
     if (self->decoder == NULL)
         Py_RETURN_NONE;
-    return PyObject_GetAttr(self->decoder, _PyIO_str_newlines);
+    return PyObject_GetAttr(self->decoder, &_Py_ID(newlines));
 }
 
 #include "clinic/stringio.c.h"
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index d5ceec7..ca59a4e 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -298,7 +298,7 @@ _PyIncrementalNewlineDecoder_decode(PyObject *myself,
     /* decode input (with the eventual \r from a previous pass) */
     if (self->decoder != Py_None) {
         output = PyObject_CallMethodObjArgs(self->decoder,
-            _PyIO_str_decode, input, final ? Py_True : Py_False, NULL);
+            &_Py_ID(decode), input, final ? Py_True : Py_False, NULL);
     }
     else {
         output = input;
@@ -509,7 +509,7 @@ _io_IncrementalNewlineDecoder_getstate_impl(nldecoder_object *self)
 
     if (self->decoder != Py_None) {
         PyObject *state = PyObject_CallMethodNoArgs(self->decoder,
-           _PyIO_str_getstate);
+           &_Py_ID(getstate));
         if (state == NULL)
             return NULL;
         if (!PyTuple_Check(state)) {
@@ -584,7 +584,7 @@ _io_IncrementalNewlineDecoder_reset_impl(nldecoder_object *self)
     self->seennl = 0;
     self->pendingcr = 0;
     if (self->decoder != Py_None)
-        return PyObject_CallMethodNoArgs(self->decoder, _PyIO_str_reset);
+        return PyObject_CallMethodNoArgs(self->decoder, &_Py_ID(reset));
     else
         Py_RETURN_NONE;
 }
@@ -883,7 +883,7 @@ _textiowrapper_decode(PyObject *decoder, PyObject *bytes, int eof)
     if (Py_IS_TYPE(decoder, &PyIncrementalNewlineDecoder_Type))
         chars = _PyIncrementalNewlineDecoder_decode(decoder, bytes, eof);
     else
-        chars = PyObject_CallMethodObjArgs(decoder, _PyIO_str_decode, bytes,
+        chars = PyObject_CallMethodObjArgs(decoder, &_Py_ID(decode), bytes,
                                            eof ? Py_True : Py_False, NULL);
 
     if (check_decoded(chars) < 0)
@@ -947,7 +947,7 @@ _textiowrapper_fix_encoder_state(textio *self)
     self->encoding_start_of_stream = 1;
 
     PyObject *cookieObj = PyObject_CallMethodNoArgs(
-        self->buffer, _PyIO_str_tell);
+        self->buffer, &_Py_ID(tell));
     if (cookieObj == NULL) {
         return -1;
     }
@@ -961,7 +961,7 @@ _textiowrapper_fix_encoder_state(textio *self)
     if (cmp == 0) {
         self->encoding_start_of_stream = 0;
         PyObject *res = PyObject_CallMethodOneArg(
-            self->encoder, _PyIO_str_setstate, _PyLong_GetZero());
+            self->encoder, &_Py_ID(setstate), _PyLong_GetZero());
         if (res == NULL) {
             return -1;
         }
@@ -1225,7 +1225,7 @@ _io_TextIOWrapper___init___impl(textio *self, PyObject *buffer,
         goto error;
     self->seekable = self->telling = r;
 
-    r = _PyObject_LookupAttr(buffer, _PyIO_str_read1, &res);
+    r = _PyObject_LookupAttr(buffer, &_Py_ID(read1), &res);
     if (r < 0) {
         goto error;
     }
@@ -1358,7 +1358,7 @@ _io_TextIOWrapper_reconfigure_impl(textio *self, PyObject *encoding,
         return NULL;
     }
 
-    PyObject *res = PyObject_CallMethodNoArgs((PyObject *)self, _PyIO_str_flush);
+    PyObject *res = PyObject_CallMethodNoArgs((PyObject *)self, &_Py_ID(flush));
     if (res == NULL) {
         return NULL;
     }
@@ -1497,7 +1497,7 @@ _io_TextIOWrapper_detach_impl(textio *self)
 {
     PyObject *buffer, *res;
     CHECK_ATTACHED(self);
-    res = PyObject_CallMethodNoArgs((PyObject *)self, _PyIO_str_flush);
+    res = PyObject_CallMethodNoArgs((PyObject *)self, &_Py_ID(flush));
     if (res == NULL)
         return NULL;
     Py_DECREF(res);
@@ -1569,7 +1569,7 @@ _textiowrapper_writeflush(textio *self)
 
     PyObject *ret;
     do {
-        ret = PyObject_CallMethodOneArg(self->buffer, _PyIO_str_write, b);
+        ret = PyObject_CallMethodOneArg(self->buffer, &_Py_ID(write), b);
     } while (ret == NULL && _PyIO_trap_eintr());
     Py_DECREF(b);
     // NOTE: We cleared buffer but we don't know how many bytes are actually written
@@ -1644,7 +1644,7 @@ _io_TextIOWrapper_write_impl(textio *self, PyObject *text)
         self->encoding_start_of_stream = 0;
     }
     else {
-        b = PyObject_CallMethodOneArg(self->encoder, _PyIO_str_encode, text);
+        b = PyObject_CallMethodOneArg(self->encoder, &_Py_ID(encode), text);
     }
 
     Py_DECREF(text);
@@ -1704,7 +1704,7 @@ _io_TextIOWrapper_write_impl(textio *self, PyObject *text)
     }
 
     if (needflush) {
-        ret = PyObject_CallMethodNoArgs(self->buffer, _PyIO_str_flush);
+        ret = PyObject_CallMethodNoArgs(self->buffer, &_Py_ID(flush));
         if (ret == NULL)
             return NULL;
         Py_DECREF(ret);
@@ -1795,7 +1795,7 @@ textiowrapper_read_chunk(textio *self, Py_ssize_t size_hint)
          * where the decoder's input buffer is empty.
          */
         PyObject *state = PyObject_CallMethodNoArgs(self->decoder,
-                                                     _PyIO_str_getstate);
+                                                     &_Py_ID(getstate));
         if (state == NULL)
             return -1;
         /* Given this, we know there was a valid snapshot point
@@ -1836,7 +1836,7 @@ textiowrapper_read_chunk(textio *self, Py_ssize_t size_hint)
         goto fail;
 
     input_chunk = PyObject_CallMethodOneArg(self->buffer,
-        (self->has_read1 ? _PyIO_str_read1: _PyIO_str_read),
+        (self->has_read1 ? &_Py_ID(read1): &_Py_ID(read)),
         chunk_size);
     Py_DECREF(chunk_size);
     if (input_chunk == NULL)
@@ -1928,7 +1928,7 @@ _io_TextIOWrapper_read_impl(textio *self, Py_ssize_t n)
                                                           bytes, 1);
         else
             decoded = PyObject_CallMethodObjArgs(
-                self->decoder, _PyIO_str_decode, bytes, Py_True, NULL);
+                self->decoder, &_Py_ID(decode), bytes, Py_True, NULL);
         Py_DECREF(bytes);
         if (check_decoded(decoded) < 0)
             goto fail;
@@ -1989,7 +1989,7 @@ _io_TextIOWrapper_read_impl(textio *self, Py_ssize_t n)
         if (chunks != NULL) {
             if (result != NULL && PyList_Append(chunks, result) < 0)
                 goto fail;
-            Py_XSETREF(result, PyUnicode_Join(_PyIO_empty_str, chunks));
+            Py_XSETREF(result, PyUnicode_Join(&_Py_STR(empty), chunks));
             if (result == NULL)
                 goto fail;
             Py_CLEAR(chunks);
@@ -2254,14 +2254,13 @@ _textiowrapper_readline(textio *self, Py_ssize_t limit)
                 goto error;
             Py_DECREF(line);
         }
-        line = PyUnicode_Join(_PyIO_empty_str, chunks);
+        line = PyUnicode_Join(&_Py_STR(empty), chunks);
         if (line == NULL)
             goto error;
         Py_CLEAR(chunks);
     }
     if (line == NULL) {
-        Py_INCREF(_PyIO_empty_str);
-        line = _PyIO_empty_str;
+        line = &_Py_STR(empty);
     }
 
     return line;
@@ -2379,7 +2378,7 @@ _textiowrapper_decoder_setstate(textio *self, cookie_type *cookie)
        utf-16, that we are expecting a BOM).
     */
     if (cookie->start_pos == 0 && cookie->dec_flags == 0) {
-        res = PyObject_CallMethodNoArgs(self->decoder, _PyIO_str_reset);
+        res = PyObject_CallMethodNoArgs(self->decoder, &_Py_ID(reset));
     }
     else {
         res = _PyObject_CallMethod(self->decoder, &_Py_ID(setstate),
@@ -2397,11 +2396,11 @@ _textiowrapper_encoder_reset(textio *self, int start_of_stream)
 {
     PyObject *res;
     if (start_of_stream) {
-        res = PyObject_CallMethodNoArgs(self->encoder, _PyIO_str_reset);
+        res = PyObject_CallMethodNoArgs(self->encoder, &_Py_ID(reset));
         self->encoding_start_of_stream = 1;
     }
     else {
-        res = PyObject_CallMethodOneArg(self->encoder, _PyIO_str_setstate,
+        res = PyObject_CallMethodOneArg(self->encoder, &_Py_ID(setstate),
                                         _PyLong_GetZero());
         self->encoding_start_of_stream = 0;
     }
@@ -2528,7 +2527,7 @@ _io_TextIOWrapper_seek_impl(textio *self, PyObject *cookieObj, int whence)
         goto fail;
     }
 
-    res = PyObject_CallMethodNoArgs((PyObject *)self, _PyIO_str_flush);
+    res = PyObject_CallMethodNoArgs((PyObject *)self, &_Py_ID(flush));
     if (res == NULL)
         goto fail;
     Py_DECREF(res);
@@ -2543,7 +2542,7 @@ _io_TextIOWrapper_seek_impl(textio *self, PyObject *cookieObj, int whence)
     posobj = PyLong_FromOff_t(cookie.start_pos);
     if (posobj == NULL)
         goto fail;
-    res = PyObject_CallMethodOneArg(self->buffer, _PyIO_str_seek, posobj);
+    res = PyObject_CallMethodOneArg(self->buffer, &_Py_ID(seek), posobj);
     Py_DECREF(posobj);
     if (res == NULL)
         goto fail;
@@ -2692,14 +2691,14 @@ _io_TextIOWrapper_tell_impl(textio *self)
 
     /* Decoder state will be restored at the end */
     saved_state = PyObject_CallMethodNoArgs(self->decoder,
-                                             _PyIO_str_getstate);
+                                             &_Py_ID(getstate));
     if (saved_state == NULL)
         goto fail;
 
 #define DECODER_GETSTATE() do { \
         PyObject *dec_buffer; \
         PyObject *_state = PyObject_CallMethodNoArgs(self->decoder, \
-            _PyIO_str_getstate); \
+            &_Py_ID(getstate)); \
         if (_state == NULL) \
             goto fail; \
         if (!PyTuple_Check(_state)) { \
@@ -2863,12 +2862,12 @@ _io_TextIOWrapper_truncate_impl(textio *self, PyObject *pos)
 
     CHECK_ATTACHED(self)
 
-    res = PyObject_CallMethodNoArgs((PyObject *)self, _PyIO_str_flush);
+    res = PyObject_CallMethodNoArgs((PyObject *)self, &_Py_ID(flush));
     if (res == NULL)
         return NULL;
     Py_DECREF(res);
 
-    return PyObject_CallMethodOneArg(self->buffer, _PyIO_str_truncate, pos);
+    return PyObject_CallMethodOneArg(self->buffer, &_Py_ID(truncate), pos);
 }
 
 static PyObject *
@@ -3077,7 +3076,7 @@ textiowrapper_iternext(textio *self)
     }
     else {
         line = PyObject_CallMethodNoArgs((PyObject *)self,
-                                          _PyIO_str_readline);
+                                          &_Py_ID(readline));
         if (line && !PyUnicode_Check(line)) {
             PyErr_Format(PyExc_OSError,
                          "readline() should have returned a str object, "
@@ -3112,7 +3111,7 @@ static PyObject *
 textiowrapper_closed_get(textio *self, void *context)
 {
     CHECK_ATTACHED(self);
-    return PyObject_GetAttr(self->buffer, _PyIO_str_closed);
+    return PyObject_GetAttr(self->buffer, &_Py_ID(closed));
 }
 
 static PyObject *
@@ -3121,7 +3120,7 @@ textiowrapper_newlines_get(textio *self, void *context)
     PyObject *res;
     CHECK_ATTACHED(self);
     if (self->decoder == NULL ||
-        _PyObject_LookupAttr(self->decoder, _PyIO_str_newlines, &res) == 0)
+        _PyObject_LookupAttr(self->decoder, &_Py_ID(newlines), &res) == 0)
     {
         Py_RETURN_NONE;
     }