Merge branch 'master' into fix-traceback-syntax-errorfix-traceback-syntax-error

5 files changed, 346 insertions, 1164 deletions

diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index 1abc9ca6f2..f2c72ebd51 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -1007,7 +1007,7 @@ io_check_errors(PyObject *errors)
 
     /* Avoid calling PyCodec_LookupError() before the codec registry is ready:
        before_PyUnicode_InitEncodings() is called. */
-    if (!interp->fs_codec.encoding) {
+    if (!interp->unicode.fs_codec.encoding) {
         return 0;
     }
 
diff --git a/Modules/_testinternalcapi.c b/Modules/_testinternalcapi.c
index 1b7563cb20..5f217dcb89 100644
--- a/Modules/_testinternalcapi.c
+++ b/Modules/_testinternalcapi.c
@@ -14,6 +14,7 @@
 #include "Python.h"
 #include "pycore_byteswap.h"     // _Py_bswap32()
 #include "pycore_initconfig.h"   // _Py_GetConfigsAsDict()
+#include "pycore_hashtable.h"    // _Py_hashtable_new()
 #include "pycore_gc.h"           // PyGC_Head
 
 
@@ -62,10 +63,101 @@ test_bswap(PyObject *self, PyObject *Py_UNUSED(args))
 }
 
 
+#define TO_PTR(ch) ((void*)(uintptr_t)ch)
+#define FROM_PTR(ptr) ((uintptr_t)ptr)
+#define VALUE(key) (1 + ((int)(key) - 'a'))
+
+static Py_uhash_t
+hash_char(const void *key)
+{
+    char ch = (char)FROM_PTR(key);
+    return ch;
+}
+
+
+static int
+hashtable_cb(_Py_hashtable_t *table,
+             const void *key_ptr, const void *value_ptr,
+             void *user_data)
+{
+    int *count = (int *)user_data;
+    char key = (char)FROM_PTR(key_ptr);
+    int value = (int)FROM_PTR(value_ptr);
+    assert(value == VALUE(key));
+    *count += 1;
+    return 0;
+}
+
+
+static PyObject*
+test_hashtable(PyObject *self, PyObject *Py_UNUSED(args))
+{
+    _Py_hashtable_t *table = _Py_hashtable_new(hash_char,
+                                               _Py_hashtable_compare_direct);
+    if (table == NULL) {
+        return PyErr_NoMemory();
+    }
+
+    // Using an newly allocated table must not crash
+    assert(table->nentries == 0);
+    assert(table->nbuckets > 0);
+    assert(_Py_hashtable_get(table, TO_PTR('x')) == NULL);
+
+    // Test _Py_hashtable_set()
+    char key;
+    for (key='a'; key <= 'z'; key++) {
+        int value = VALUE(key);
+        if (_Py_hashtable_set(table, TO_PTR(key), TO_PTR(value)) < 0) {
+            _Py_hashtable_destroy(table);
+            return PyErr_NoMemory();
+        }
+    }
+    assert(table->nentries == 26);
+    assert(table->nbuckets > table->nentries);
+
+    // Test _Py_hashtable_get_entry()
+    for (key='a'; key <= 'z'; key++) {
+        _Py_hashtable_entry_t *entry = _Py_hashtable_get_entry(table, TO_PTR(key));
+        assert(entry != NULL);
+        assert(entry->key = TO_PTR(key));
+        assert(entry->value = TO_PTR(VALUE(key)));
+    }
+
+    // Test _Py_hashtable_get()
+    for (key='a'; key <= 'z'; key++) {
+        void *value_ptr = _Py_hashtable_get(table, TO_PTR(key));
+        assert((int)FROM_PTR(value_ptr) == VALUE(key));
+    }
+
+    // Test _Py_hashtable_steal()
+    key = 'p';
+    void *value_ptr = _Py_hashtable_steal(table, TO_PTR(key));
+    assert((int)FROM_PTR(value_ptr) == VALUE(key));
+    assert(table->nentries == 25);
+    assert(_Py_hashtable_get_entry(table, TO_PTR(key)) == NULL);
+
+    // Test _Py_hashtable_foreach()
+    int count = 0;
+    int res = _Py_hashtable_foreach(table, hashtable_cb, &count);
+    assert(res == 0);
+    assert(count == 25);
+
+    // Test _Py_hashtable_clear()
+    _Py_hashtable_clear(table);
+    assert(table->nentries == 0);
+    assert(table->nbuckets > 0);
+    assert(_Py_hashtable_get(table, TO_PTR('x')) == NULL);
+
+    _Py_hashtable_destroy(table);
+    Py_RETURN_NONE;
+}
+
+
 static PyMethodDef TestMethods[] = {
     {"get_configs", get_configs, METH_NOARGS},
     {"get_recursion_depth", get_recursion_depth, METH_NOARGS},
     {"test_bswap", test_bswap, METH_NOARGS},
+    {"test_hashtable", test_hashtable, METH_NOARGS},
     {NULL, NULL} /* sentinel */
 };
 
diff --git a/Modules/_xxsubinterpretersmodule.c b/Modules/_xxsubinterpretersmodule.c
index 18dd8918e7..8a6fce9e0b 100644
--- a/Modules/_xxsubinterpretersmodule.c
+++ b/Modules/_xxsubinterpretersmodule.c
@@ -1,4 +1,5 @@
-/* _interpreters module */
+
+/* interpreters module */
 /* low-level access to interpreter primitives */
 
 #include "Python.h"
@@ -6,927 +7,35 @@
 #include "interpreteridobject.h"
 
 
-// XXX Emit a warning?
-#define IGNORE_FAILURE(msg) \
-    fprintf(stderr, " -----\nRunFailedError: %s\n", msg); \
-    PyErr_PrintEx(0); \
-    fprintf(stderr, " -----\n"); \
-    PyErr_Clear();
-
-typedef void (*_deallocfunc)(void *);
-
-static PyInterpreterState *
-_get_current(void)
-{
-    // _PyInterpreterState_Get() aborts if lookup fails, so don't need
-    // to check the result for NULL.
-    return _PyInterpreterState_Get();
-}
-
-
-/* string utils *************************************************************/
-
-// PyMem_Free() must be used to dealocate the resulting string.
 static char *
-_strdup_and_size(const char *data, Py_ssize_t *psize, _deallocfunc *dealloc)
-{
-    if (data == NULL) {
-        if (psize != NULL) {
-            *psize = 0;
-        }
-        if (dealloc != NULL) {
-            *dealloc = NULL;
-        }
-        return "";
-    }
-
-    Py_ssize_t size;
-    if (psize == NULL) {
-        size = strlen(data);
-    } else {
-        size = *psize;
-        if (size == 0) {
-            size = strlen(data);
-            *psize = size;  // The size "return" value.
-        }
-    }
-    char *copied = PyMem_Malloc(size+1);
-    if (copied == NULL) {
-        PyErr_NoMemory();
-        return NULL;
-    }
-    if (dealloc != NULL) {
-        *dealloc = PyMem_Free;
-    }
-    memcpy(copied, data, size+1);
-    return copied;
-}
-
-static const char *
-_pyobj_get_str_and_size(PyObject *obj, Py_ssize_t *psize)
-{
-    if (PyUnicode_Check(obj)) {
-        return PyUnicode_AsUTF8AndSize(obj, psize);
-    } else {
-        const char *data = NULL;
-        PyBytes_AsStringAndSize(obj, (char **)&data, psize);
-        return data;
-    }
-}
-
-/* "raw" strings */
-
-typedef struct _rawstring {
-    Py_ssize_t size;
-    const char *data;
-    _deallocfunc dealloc;
-} _rawstring;
-
-static void
-_rawstring_init(_rawstring *raw)
-{
-    raw->size = 0;
-    raw->data = NULL;
-    raw->dealloc = NULL;
-}
-
-static _rawstring *
-_rawstring_new(void)
-{
-    _rawstring *raw = PyMem_NEW(_rawstring, 1);
-    if (raw == NULL) {
-        PyErr_NoMemory();
-        return NULL;
-    }
-    _rawstring_init(raw);
-    return raw;
-}
-
-static void
-_rawstring_clear(_rawstring *raw)
-{
-    if (raw->data != NULL && raw->dealloc != NULL) {
-        (*raw->dealloc)((void *)raw->data);
-    }
-    _rawstring_init(raw);
-}
-
-static void
-_rawstring_free(_rawstring *raw)
-{
-    _rawstring_clear(raw);
-    PyMem_Free(raw);
-}
-
-static int
-_rawstring_is_clear(_rawstring *raw)
-{
-    return raw->size == 0 && raw->data == NULL && raw->dealloc == NULL;
-}
-
-//static void
-//_rawstring_move(_rawstring *raw, _rawstring *src)
-//{
-//    raw->size = src->size;
-//    raw->data = src->data;
-//    raw->dealloc = src->dealloc;
-//    _rawstring_init(src);
-//}
-
-static void
-_rawstring_proxy(_rawstring *raw, const char *str)
+_copy_raw_string(PyObject *strobj)
 {
+    const char *str = PyUnicode_AsUTF8(strobj);
     if (str == NULL) {
-        str = "";
-    }
-    raw->size = strlen(str);
-    raw->data = str;
-    raw->dealloc = NULL;
-}
-
-static int
-_rawstring_buffer(_rawstring *raw, Py_ssize_t size)
-{
-    raw->data = PyMem_Malloc(size+1);
-    if (raw->data == NULL) {
-        PyErr_NoMemory();
-        return -1;
-    }
-    raw->size = size;
-    raw->dealloc = PyMem_Free;
-    return 0;
-}
-
-static int
-_rawstring_strcpy(_rawstring *raw, const char *str, Py_ssize_t size)
-{
-    _deallocfunc dealloc = NULL;
-    const char *copied = _strdup_and_size(str, &size, &dealloc);
-    if (copied == NULL) {
-        return -1;
-    }
-
-    raw->size = size;
-    raw->dealloc = dealloc;
-    raw->data = copied;
-    return 0;
-}
-
-static int
-_rawstring_from_pyobj(_rawstring *raw, PyObject *obj)
-{
-    Py_ssize_t size = 0;
-    const char *data = _pyobj_get_str_and_size(obj, &size);
-    if (PyErr_Occurred()) {
-        return -1;
-    }
-    if (_rawstring_strcpy(raw, data, size) != 0) {
-        return -1;
-    }
-    return 0;
-}
-
-static int
-_rawstring_from_pyobj_attr(_rawstring *raw, PyObject *obj, const char *attr)
-{
-    int res = -1;
-    PyObject *valueobj = PyObject_GetAttrString(obj, attr);
-    if (valueobj == NULL) {
-        goto done;
-    }
-    if (!PyUnicode_Check(valueobj)) {
-        // XXX PyObject_Str()?  Repr()?
-        goto done;
-    }
-    const char *valuestr = PyUnicode_AsUTF8(valueobj);
-    if (valuestr == NULL) {
-        if (PyErr_Occurred()) {
-            goto done;
-        }
-    } else if (_rawstring_strcpy(raw, valuestr, 0) != 0) {
-        _rawstring_clear(raw);
-        goto done;
-    }
-    res = 0;
-
-done:
-    Py_XDECREF(valueobj);
-    return res;
-}
-
-static PyObject *
-_rawstring_as_pybytes(_rawstring *raw)
-{
-    return PyBytes_FromStringAndSize(raw->data, raw->size);
-}
-
-
-/* object utils *************************************************************/
-
-static void
-_pyobj_identify_type(PyObject *obj, _rawstring *modname, _rawstring *clsname)
-{
-    PyObject *objtype = (PyObject *)Py_TYPE(obj);
-
-    // Try __module__ and __name__.
-    if (_rawstring_from_pyobj_attr(modname, objtype, "__module__") != 0) {
-        // Fall back to the previous values in "modname".
-        IGNORE_FAILURE("bad __module__");
-    }
-    if (_rawstring_from_pyobj_attr(clsname, objtype, "__name__") != 0) {
-        // Fall back to the previous values in "clsname".
-        IGNORE_FAILURE("bad __name__");
-    }
-
-    // XXX Fall back to __qualname__?
-    // XXX Fall back to tp_name?
-}
-
-static PyObject *
-_pyobj_get_class(const char *modname, const char *clsname)
-{
-    assert(clsname != NULL);
-    if (modname == NULL) {
-        modname = "builtins";
-    }
-
-    PyObject *module = PyImport_ImportModule(modname);
-    if (module == NULL) {
-        return NULL;
-    }
-    PyObject *cls = PyObject_GetAttrString(module, clsname);
-    Py_DECREF(module);
-    return cls;
-}
-
-static PyObject *
-_pyobj_create(const char *modname, const char *clsname, PyObject *arg)
-{
-    PyObject *cls = _pyobj_get_class(modname, clsname);
-    if (cls == NULL) {
         return NULL;
     }
-    PyObject *obj = NULL;
-    if (arg == NULL) {
-        obj = _PyObject_CallNoArg(cls);
-    } else {
-        obj = PyObject_CallFunction(cls, "O", arg);
-    }
-    Py_DECREF(cls);
-    return obj;
-}
-
-
-/* object snapshots */
-
-typedef struct _objsnapshot {
-    // If modname is NULL then try "builtins" and "__main__".
-    _rawstring modname;
-    // clsname is required.
-    _rawstring clsname;
-
-    // The rest are optional.
-
-    // The serialized exception.
-    _rawstring *serialized;
-} _objsnapshot;
-
-static void
-_objsnapshot_init(_objsnapshot *osn)
-{
-    _rawstring_init(&osn->modname);
-    _rawstring_init(&osn->clsname);
-    osn->serialized = NULL;
-}
-
-//static _objsnapshot *
-//_objsnapshot_new(void)
-//{
-//    _objsnapshot *osn = PyMem_NEW(_objsnapshot, 1);
-//    if (osn == NULL) {
-//        PyErr_NoMemory();
-//        return NULL;
-//    }
-//    _objsnapshot_init(osn);
-//    return osn;
-//}
-
-static void
-_objsnapshot_clear(_objsnapshot *osn)
-{
-    _rawstring_clear(&osn->modname);
-    _rawstring_clear(&osn->clsname);
-    if (osn->serialized != NULL) {
-        _rawstring_free(osn->serialized);
-        osn->serialized = NULL;
-    }
-}
-
-//static void
-//_objsnapshot_free(_objsnapshot *osn)
-//{
-//    _objsnapshot_clear(osn);
-//    PyMem_Free(osn);
-//}
-
-#ifndef NDEBUG
-static int
-_objsnapshot_is_clear(_objsnapshot *osn)
-{
-    return osn->serialized == NULL
-        && _rawstring_is_clear(&osn->modname)
-        && _rawstring_is_clear(&osn->clsname);
-}
-#endif
-
-static void
-_objsnapshot_summarize(_objsnapshot *osn, _rawstring *rawbuf, const char *msg)
-{
-    if (msg == NULL || *msg == '\0') {
-        // XXX Keep it NULL?
-        // XXX Keep it an empty string?
-        // XXX Use something more informative?
-        msg = "<no message>";
-    }
-    const char *clsname = osn->clsname.data;
-    const char *modname = osn->modname.data;
-    if (modname && *modname == '\0') {
-        modname = NULL;
-    }
-
-    // Prep the buffer.
-    Py_ssize_t size = strlen(clsname);
-    if (modname != NULL) {
-        if (strcmp(modname, "builtins") == 0) {
-            modname = NULL;
-        } else if (strcmp(modname, "__main__") == 0) {
-            modname = NULL;
-        } else {
-            size += strlen(modname) + 1;
-        }
-    }
-    if (msg != NULL) {
-        size += strlen(": ") + strlen(msg);
-    }
-    if (modname != NULL || msg != NULL) {
-        if (_rawstring_buffer(rawbuf, size) != 0) {
-            IGNORE_FAILURE("could not summarize object snapshot");
-            return;
-        }
-    }
-    // ...else we'll proxy clsname as-is, so no need to allocate a buffer.
-
-    // XXX Use __qualname__ somehow?
-    char *buf = (char *)rawbuf->data;
-    if (modname != NULL) {
-        if (msg != NULL) {
-            snprintf(buf, size+1, "%s.%s: %s", modname, clsname, msg);
-        } else {
-            snprintf(buf, size+1, "%s.%s", modname, clsname);
-        }
-    } else if (msg != NULL) {
-        snprintf(buf, size+1, "%s: %s", clsname, msg);
-    } else {
-        _rawstring_proxy(rawbuf, clsname);
-    }
-}
-
-static _rawstring *
-_objsnapshot_get_minimal_summary(_objsnapshot *osn, PyObject *obj)
-{
-    const char *str = NULL;
-    PyObject *objstr = PyObject_Str(obj);
-    if (objstr == NULL) {
-        PyErr_Clear();
-    } else {
-        str = PyUnicode_AsUTF8(objstr);
-        if (str == NULL) {
-            PyErr_Clear();
-        }
-    }
-
-    _rawstring *summary = _rawstring_new();
-    if (summary == NULL) {
-        return NULL;
-    }
-    _objsnapshot_summarize(osn, summary, str);
-    return summary;
-}
-
-static void
-_objsnapshot_extract(_objsnapshot *osn, PyObject *obj)
-{
-    assert(_objsnapshot_is_clear(osn));
-
-    // Get the "qualname".
-    _rawstring_proxy(&osn->modname, "<unknown>");
-    _rawstring_proxy(&osn->clsname, "<unknown>");
-    _pyobj_identify_type(obj, &osn->modname, &osn->clsname);
-
-    // Serialize the object.
-    // XXX Use marshal?
-    PyObject *pickle = PyImport_ImportModule("pickle");
-    if (pickle == NULL) {
-        IGNORE_FAILURE("could not serialize object: pickle import failed");
-        return;
-    }
-    PyObject *objdata = PyObject_CallMethod(pickle, "dumps", "(O)", obj);
-    Py_DECREF(pickle);
-    if (objdata == NULL) {
-        IGNORE_FAILURE("could not serialize object: pickle.dumps failed");
-    } else {
-        _rawstring *serialized = _rawstring_new();
-        int res = _rawstring_from_pyobj(serialized, objdata);
-        Py_DECREF(objdata);
-        if (res != 0) {
-            IGNORE_FAILURE("could not serialize object: raw str failed");
-            _rawstring_free(serialized);
-        } else if (serialized->size == 0) {
-            _rawstring_free(serialized);
-        } else {
-            osn->serialized = serialized;
-        }
-    }
-}
-
-static PyObject *
-_objsnapshot_resolve_serialized(_objsnapshot *osn)
-{
-    assert(osn->serialized != NULL);
-
-    // XXX Use marshal?
-    PyObject *pickle = PyImport_ImportModule("pickle");
-    if (pickle == NULL) {
-        return NULL;
-    }
-    PyObject *objdata = _rawstring_as_pybytes(osn->serialized);
-    if (objdata == NULL) {
-        return NULL;
-    } else {
-        PyObject *obj = PyObject_CallMethod(pickle, "loads", "O", objdata);
-        Py_DECREF(objdata);
-        return obj;
-    }
-}
-
-static PyObject *
-_objsnapshot_resolve_naive(_objsnapshot *osn, PyObject *arg)
-{
-    if (_rawstring_is_clear(&osn->clsname)) {
-        // We can't proceed without at least the class name.
-        PyErr_SetString(PyExc_ValueError, "missing class name");
-        return NULL;
-    }
-
-    if (osn->modname.data != NULL) {
-        return _pyobj_create(osn->modname.data, osn->clsname.data, arg);
-    } else {
-        PyObject *obj = _pyobj_create("builtins", osn->clsname.data, arg);
-        if (obj == NULL) {
-            PyErr_Clear();
-            obj = _pyobj_create("__main__", osn->clsname.data, arg);
-        }
-        return obj;
-    }
-}
-
-static PyObject *
-_objsnapshot_resolve(_objsnapshot *osn)
-{
-    if (osn->serialized != NULL) {
-        PyObject *obj = _objsnapshot_resolve_serialized(osn);
-        if (obj != NULL) {
-            return obj;
-        }
-        IGNORE_FAILURE("could not de-serialize object");
-    }
-
-    // Fall back to naive resolution.
-    return _objsnapshot_resolve_naive(osn, NULL);
-}
-
-
-/* exception utils **********************************************************/
-
-// _pyexc_create is inspired by _PyErr_SetObject().
-
-static PyObject *
-_pyexc_create(PyObject *exctype, const char *msg, PyObject *tb)
-{
-    assert(exctype != NULL && PyExceptionClass_Check(exctype));
-
-    PyObject *curtype = NULL, *curexc = NULL, *curtb = NULL;
-    PyErr_Fetch(&curtype, &curexc, &curtb);
-
-    // Create the object.
-    PyObject *exc = NULL;
-    if (msg != NULL) {
-        PyObject *msgobj = PyUnicode_FromString(msg);
-        if (msgobj == NULL) {
-            IGNORE_FAILURE("could not deserialize propagated error message");
-        }
-        exc = _PyObject_CallOneArg(exctype, msgobj);
-        Py_XDECREF(msgobj);
-    } else {
-        exc = _PyObject_CallNoArg(exctype);
-    }
-    if (exc == NULL) {
-        return NULL;
-    }
-
-    // Set the traceback, if any.
-    if (tb == NULL) {
-        tb = curtb;
-    }
-    if (tb != NULL) {
-        // This does *not* steal a reference!
-        PyException_SetTraceback(exc, tb);
-    }
-
-    PyErr_Restore(curtype, curexc, curtb);
-
-    return exc;
-}
-
-/* traceback snapshots */
-
-typedef struct _tbsnapshot {
-    _rawstring tbs_funcname;
-    _rawstring tbs_filename;
-    int tbs_lineno;
-    struct _tbsnapshot *tbs_next;
-} _tbsnapshot;
-
-static void
-_tbsnapshot_init(_tbsnapshot *tbs)
-{
-    _rawstring_init(&tbs->tbs_funcname);
-    _rawstring_init(&tbs->tbs_filename);
-    tbs->tbs_lineno = -1;
-    tbs->tbs_next = NULL;
-}
-
-static _tbsnapshot *
-_tbsnapshot_new(void)
-{
-    _tbsnapshot *tbs = PyMem_NEW(_tbsnapshot, 1);
-    if (tbs == NULL) {
-        PyErr_NoMemory();
-        return NULL;
-    }
-    _tbsnapshot_init(tbs);
-    return tbs;
-}
-
-static void _tbsnapshot_free(_tbsnapshot *);  // forward
-
-static void
-_tbsnapshot_clear(_tbsnapshot *tbs)
-{
-    _rawstring_clear(&tbs->tbs_funcname);
-    _rawstring_clear(&tbs->tbs_filename);
-    tbs->tbs_lineno = -1;
-    if (tbs->tbs_next != NULL) {
-        _tbsnapshot_free(tbs->tbs_next);
-        tbs->tbs_next = NULL;
-    }
-}
-
-static void
-_tbsnapshot_free(_tbsnapshot *tbs)
-{
-    _tbsnapshot_clear(tbs);
-    PyMem_Free(tbs);
-}
-
-#ifndef NDEBUG
-static int
-_tbsnapshot_is_clear(_tbsnapshot *tbs)
-{
-    return tbs->tbs_lineno == -1 && tbs->tbs_next == NULL
-        && _rawstring_is_clear(&tbs->tbs_funcname)
-        && _rawstring_is_clear(&tbs->tbs_filename);
-}
-#endif
-
-static int
-_tbsnapshot_from_pytb(_tbsnapshot *tbs, PyTracebackObject *pytb)
-{
-    assert(_tbsnapshot_is_clear(tbs));
-    assert(pytb != NULL);
-
-    PyCodeObject *pycode = pytb->tb_frame->f_code;
-    const char *funcname = PyUnicode_AsUTF8(pycode->co_name);
-    if (_rawstring_strcpy(&tbs->tbs_funcname, funcname, 0) != 0) {
-        goto error;
-    }
-    const char *filename = PyUnicode_AsUTF8(pycode->co_filename);
-    if (_rawstring_strcpy(&tbs->tbs_filename, filename, 0) != 0) {
-        goto error;
-    }
-    tbs->tbs_lineno = pytb->tb_lineno;
-
-    return 0;
-
-error:
-    _tbsnapshot_clear(tbs);
-    return -1;
-}
-
-static int
-_tbsnapshot_extract(_tbsnapshot *tbs, PyTracebackObject *pytb)
-{
-    assert(_tbsnapshot_is_clear(tbs));
-    assert(pytb != NULL);
-
-    _tbsnapshot *next = NULL;
-    while (pytb->tb_next != NULL) {
-        _tbsnapshot *_next = _tbsnapshot_new();
-        if (_next == NULL) {
-            goto error;
-        }
-        if (_tbsnapshot_from_pytb(_next, pytb) != 0) {
-            goto error;
-        }
-        if (next != NULL) {
-            _next->tbs_next = next;
-        }
-        next = _next;
-        pytb = pytb->tb_next;
-    }
-    if (_tbsnapshot_from_pytb(tbs, pytb) != 0) {
-        goto error;
-    }
-    tbs->tbs_next = next;
-
-    return 0;
-
-error:
-    _tbsnapshot_clear(tbs);
-    return -1;
-}
-
-static PyObject *
-_tbsnapshot_resolve(_tbsnapshot *tbs)
-{
-    assert(!PyErr_Occurred());
-    // At this point there should be no traceback set yet.
-
-    while (tbs != NULL) {
-        const char *funcname = tbs->tbs_funcname.data;
-        const char *filename = tbs->tbs_filename.data;
-        _PyTraceback_Add(funcname ? funcname : "",
-                         filename ? filename : "",
-                         tbs->tbs_lineno);
-        tbs = tbs->tbs_next;
-    }
-
-    PyObject *exctype = NULL, *excval = NULL, *tb = NULL;
-    PyErr_Fetch(&exctype, &excval, &tb);
-    // Leave it cleared.
-    return tb;
-}
-
-/* exception snapshots */
-
-typedef struct _excsnapshot {
-    _objsnapshot es_object;
-    _rawstring *es_msg;
-    struct _excsnapshot *es_cause;
-    struct _excsnapshot *es_context;
-    char es_suppress_context;
-    struct _tbsnapshot *es_traceback;
-} _excsnapshot;
-
-static void
-_excsnapshot_init(_excsnapshot *es)
-{
-    _objsnapshot_init(&es->es_object);
-    es->es_msg = NULL;
-    es->es_cause = NULL;
-    es->es_context = NULL;
-    es->es_suppress_context = 0;
-    es->es_traceback = NULL;
-}
-
-static _excsnapshot *
-_excsnapshot_new(void) {
-    _excsnapshot *es = PyMem_NEW(_excsnapshot, 1);
-    if (es == NULL) {
+    char *copied = PyMem_Malloc(strlen(str)+1);
+    if (copied == NULL) {
         PyErr_NoMemory();
         return NULL;
     }
-    _excsnapshot_init(es);
-    return es;
-}
-
-static void _excsnapshot_free(_excsnapshot *);  // forward
-
-static void
-_excsnapshot_clear(_excsnapshot *es)
-{
-    _objsnapshot_clear(&es->es_object);
-    if (es->es_msg != NULL) {
-        _rawstring_free(es->es_msg);
-        es->es_msg = NULL;
-    }
-    if (es->es_cause != NULL) {
-        _excsnapshot_free(es->es_cause);
-        es->es_cause = NULL;
-    }
-    if (es->es_context != NULL) {
-        _excsnapshot_free(es->es_context);
-        es->es_context = NULL;
-    }
-    es->es_suppress_context = 0;
-    if (es->es_traceback != NULL) {
-        _tbsnapshot_free(es->es_traceback);
-        es->es_traceback = NULL;
-    }
-}
-
-static void
-_excsnapshot_free(_excsnapshot *es)
-{
-    _excsnapshot_clear(es);
-    PyMem_Free(es);
-}
-
-#ifndef NDEBUG
-static int
-_excsnapshot_is_clear(_excsnapshot *es)
-{
-    return es->es_suppress_context == 0
-        && es->es_cause == NULL
-        && es->es_context == NULL
-        && es->es_traceback == NULL
-        && es->es_msg == NULL
-        && _objsnapshot_is_clear(&es->es_object);
-}
-#endif
-
-static PyObject *
-_excsnapshot_get_exc_naive(_excsnapshot *es)
-{
-    _rawstring buf;
-    const char *msg = NULL;
-    if (es->es_msg != NULL) {
-        msg = es->es_msg->data;
-    } else {
-        _objsnapshot_summarize(&es->es_object, &buf, NULL);
-        if (buf.size > 0) {
-            msg = buf.data;
-        }
-    }
-
-    PyObject *exc = NULL;
-    // XXX Use _objsnapshot_resolve_naive()?
-    const char *modname = es->es_object.modname.size > 0
-        ? es->es_object.modname.data
-        : NULL;
-    PyObject *exctype = _pyobj_get_class(modname, es->es_object.clsname.data);
-    if (exctype != NULL) {
-        exc = _pyexc_create(exctype, msg, NULL);
-        Py_DECREF(exctype);
-        if (exc != NULL) {
-            return exc;
-        }
-        PyErr_Clear();
-    } else {
-        PyErr_Clear();
-    }
-    exctype = PyExc_Exception;
-    return _pyexc_create(exctype, msg, NULL);
-}
-
-static PyObject *
-_excsnapshot_get_exc(_excsnapshot *es)
-{
-    assert(!_objsnapshot_is_clear(&es->es_object));
-
-    PyObject *exc = _objsnapshot_resolve(&es->es_object);
-    if (exc == NULL) {
-        // Fall back to resolving the object.
-        PyObject *curtype = NULL, *curexc = NULL, *curtb = NULL;
-        PyErr_Fetch(&curtype, &curexc, &curtb);
-
-        exc = _excsnapshot_get_exc_naive(es);
-        if (exc == NULL) {
-            PyErr_Restore(curtype, curexc, curtb);
-            return NULL;
-        }
-    }
-    // People can do some weird stuff...
-    if (!PyExceptionInstance_Check(exc)) {
-        // We got a bogus "exception".
-        Py_DECREF(exc);
-        PyErr_SetString(PyExc_TypeError, "expected exception");
-        return NULL;
-    }
-    return exc;
-}
-
-static void _excsnapshot_extract(_excsnapshot *, PyObject *);
-static void
-_excsnapshot_extract(_excsnapshot *es, PyObject *excobj)
-{
-    assert(_excsnapshot_is_clear(es));
-    assert(PyExceptionInstance_Check(excobj));
-
-    _objsnapshot_extract(&es->es_object, excobj);
-
-    es->es_msg = _objsnapshot_get_minimal_summary(&es->es_object, excobj);
-    if (es->es_msg == NULL) {
-        PyErr_Clear();
-    }
-
-    PyBaseExceptionObject *exc = (PyBaseExceptionObject *)excobj;
-
-    if (exc->cause != NULL && exc->cause != Py_None) {
-        es->es_cause = _excsnapshot_new();
-        _excsnapshot_extract(es->es_cause, exc->cause);
-    }
-
-    if (exc->context != NULL && exc->context != Py_None) {
-        es->es_context = _excsnapshot_new();
-        _excsnapshot_extract(es->es_context, exc->context);
-    }
-
-    es->es_suppress_context = exc->suppress_context;
-
-    PyObject *tb = PyException_GetTraceback(excobj);
-    if (PyErr_Occurred()) {
-        IGNORE_FAILURE("could not get traceback");
-    } else if (tb == Py_None) {
-        Py_DECREF(tb);
-        tb = NULL;
-    }
-    if (tb != NULL) {
-        es->es_traceback = _tbsnapshot_new();
-        if (_tbsnapshot_extract(es->es_traceback,
-                                (PyTracebackObject *)tb) != 0) {
-            IGNORE_FAILURE("could not extract __traceback__");
-        }
-    }
+    strcpy(copied, str);
+    return copied;
 }
 
-static PyObject *
-_excsnapshot_resolve(_excsnapshot *es)
+static PyInterpreterState *
+_get_current(void)
 {
-    PyObject *exc = _excsnapshot_get_exc(es);
-    if (exc == NULL) {
-        return NULL;
-    }
-
-    if (es->es_traceback != NULL) {
-        PyObject *tb = _tbsnapshot_resolve(es->es_traceback);
-        if (tb == NULL) {
-            // The snapshot is still somewhat useful without this.
-            IGNORE_FAILURE("could not deserialize traceback");
-        } else {
-            // This does not steal references.
-            PyException_SetTraceback(exc, tb);
-            Py_DECREF(tb);
-        }
-    }
-    // NULL means "not set".
-
-    if (es->es_context != NULL) {
-        PyObject *context = _excsnapshot_resolve(es->es_context);
-        if (context == NULL) {
-            // The snapshot is still useful without this.
-            IGNORE_FAILURE("could not deserialize __context__");
-        } else {
-            // This steals references but we have one to give.
-            PyException_SetContext(exc, context);
-        }
-    }
-    // NULL means "not set".
-
-    if (es->es_cause != NULL) {
-        PyObject *cause = _excsnapshot_resolve(es->es_cause);
-        if (cause == NULL) {
-            // The snapshot is still useful without this.
-            IGNORE_FAILURE("could not deserialize __cause__");
-        } else {
-            // This steals references, but we have one to give.
-            PyException_SetCause(exc, cause);
-        }
-    }
-    // NULL means "not set".
-
-    ((PyBaseExceptionObject *)exc)->suppress_context = es->es_suppress_context;
-
-    return exc;
+    // PyInterpreterState_Get() aborts if lookup fails, so don't need
+    // to check the result for NULL.
+    return PyInterpreterState_Get();
 }
 
 
 /* data-sharing-specific code ***********************************************/
 
-/* shared "object" */
-
 struct _sharednsitem {
-    _rawstring name;
+    char *name;
     _PyCrossInterpreterData data;
 };
 
@@ -935,7 +44,8 @@ static void _sharednsitem_clear(struct _sharednsitem *);  // forward
 static int
 _sharednsitem_init(struct _sharednsitem *item, PyObject *key, PyObject *value)
 {
-    if (_rawstring_from_pyobj(&item->name, key) != 0) {
+    item->name = _copy_raw_string(key);
+    if (item->name == NULL) {
         return -1;
     }
     if (_PyObject_GetCrossInterpreterData(value, &item->data) != 0) {
@@ -948,14 +58,17 @@ _sharednsitem_init(struct _sharednsitem *item, PyObject *key, PyObject *value)
 static void
 _sharednsitem_clear(struct _sharednsitem *item)
 {
-    _rawstring_clear(&item->name);
+    if (item->name != NULL) {
+        PyMem_Free(item->name);
+        item->name = NULL;
+    }
     _PyCrossInterpreterData_Release(&item->data);
 }
 
 static int
 _sharednsitem_apply(struct _sharednsitem *item, PyObject *ns)
 {
-    PyObject *name = PyUnicode_FromString(item->name.data);
+    PyObject *name = PyUnicode_FromString(item->name);
     if (name == NULL) {
         return -1;
     }
@@ -1046,121 +159,121 @@ _sharedns_apply(_sharedns *shared, PyObject *ns)
     return 0;
 }
 
-/* shared exception */
-
 // Ultimately we'd like to preserve enough information about the
 // exception and traceback that we could re-constitute (or at least
 // simulate, a la traceback.TracebackException), and even chain, a copy
 // of the exception in the calling interpreter.
 
 typedef struct _sharedexception {
-    _excsnapshot snapshot;
-    _rawstring msg;
+    char *name;
+    char *msg;
 } _sharedexception;
 
-static void
-_sharedexception_init(_sharedexception *she)
-{
-    _excsnapshot_init(&she->snapshot);
-    _rawstring_init(&she->msg);
-}
-
 static _sharedexception *
 _sharedexception_new(void)
 {
-    _sharedexception *she = PyMem_NEW(_sharedexception, 1);
-    if (she == NULL) {
+    _sharedexception *err = PyMem_NEW(_sharedexception, 1);
+    if (err == NULL) {
         PyErr_NoMemory();
         return NULL;
     }
-    _sharedexception_init(she);
-    return she;
+    err->name = NULL;
+    err->msg = NULL;
+    return err;
 }
 
 static void
-_sharedexception_clear(_sharedexception *she)
+_sharedexception_clear(_sharedexception *exc)
 {
-    _excsnapshot_clear(&she->snapshot);
-    _rawstring_clear(&she->msg);
+    if (exc->name != NULL) {
+        PyMem_Free(exc->name);
+    }
+    if (exc->msg != NULL) {
+        PyMem_Free(exc->msg);
+    }
 }
 
 static void
-_sharedexception_free(_sharedexception *she)
+_sharedexception_free(_sharedexception *exc)
 {
-    _sharedexception_clear(she);
-    PyMem_Free(she);
+    _sharedexception_clear(exc);
+    PyMem_Free(exc);
 }
 
-#ifndef NDEBUG
-static int
-_sharedexception_is_clear(_sharedexception *she)
+static _sharedexception *
+_sharedexception_bind(PyObject *exctype, PyObject *exc, PyObject *tb)
 {
-    return 1
-        && _excsnapshot_is_clear(&she->snapshot)
-        && _rawstring_is_clear(&she->msg);
-}
-#endif
+    assert(exctype != NULL);
+    char *failure = NULL;
 
-static PyObject *
-_sharedexception_get_cause(_sharedexception *sharedexc)
-{
-    // FYI, "cause" is already normalized.
-    PyObject *cause = _excsnapshot_resolve(&sharedexc->snapshot);
-    if (cause == NULL) {
-        if (PyErr_Occurred()) {
-            IGNORE_FAILURE("could not deserialize exc snapshot");
-        }
-        return NULL;
+    _sharedexception *err = _sharedexception_new();
+    if (err == NULL) {
+        goto finally;
     }
-    // XXX Ensure "cause" has a traceback.
-    return cause;
-}
 
-static void
-_sharedexception_extract(_sharedexception *she, PyObject *exc)
-{
-    assert(_sharedexception_is_clear(she));
-    assert(exc != NULL);
+    PyObject *name = PyUnicode_FromFormat("%S", exctype);
+    if (name == NULL) {
+        failure = "unable to format exception type name";
+        goto finally;
+    }
+    err->name = _copy_raw_string(name);
+    Py_DECREF(name);
+    if (err->name == NULL) {
+        if (PyErr_ExceptionMatches(PyExc_MemoryError)) {
+            failure = "out of memory copying exception type name";
+        } else {
+            failure = "unable to encode and copy exception type name";
+        }
+        goto finally;
+    }
 
-    _excsnapshot_extract(&she->snapshot, exc);
+    if (exc != NULL) {
+        PyObject *msg = PyUnicode_FromFormat("%S", exc);
+        if (msg == NULL) {
+            failure = "unable to format exception message";
+            goto finally;
+        }
+        err->msg = _copy_raw_string(msg);
+        Py_DECREF(msg);
+        if (err->msg == NULL) {
+            if (PyErr_ExceptionMatches(PyExc_MemoryError)) {
+                failure = "out of memory copying exception message";
+            } else {
+                failure = "unable to encode and copy exception message";
+            }
+            goto finally;
+        }
+    }
 
-    // Compose the message.
-    const char *msg = NULL;
-    PyObject *msgobj = PyUnicode_FromFormat("%S", exc);
-    if (msgobj == NULL) {
-        IGNORE_FAILURE("unable to format exception message");
-    } else {
-        msg = PyUnicode_AsUTF8(msgobj);
-        if (PyErr_Occurred()) {
-            PyErr_Clear();
+finally:
+    if (failure != NULL) {
+        PyErr_Clear();
+        if (err->name != NULL) {
+            PyMem_Free(err->name);
+            err->name = NULL;
         }
+        err->msg = failure;
     }
-    _objsnapshot_summarize(&she->snapshot.es_object, &she->msg, msg);
-    Py_XDECREF(msgobj);
+    return err;
 }
 
-static PyObject *
-_sharedexception_resolve(_sharedexception *sharedexc, PyObject *wrapperclass)
+static void
+_sharedexception_apply(_sharedexception *exc, PyObject *wrapperclass)
 {
-    assert(!PyErr_Occurred());
-
-    // Get the exception object (already normalized).
-    PyObject *exc = _pyexc_create(wrapperclass, sharedexc->msg.data, NULL);
-    assert(exc != NULL);
-
-    // Set __cause__, is possible.
-    PyObject *cause = _sharedexception_get_cause(sharedexc);
-    if (cause != NULL) {
-        // Set __context__.
-        Py_INCREF(cause);  // PyException_SetContext() steals a reference.
-        PyException_SetContext(exc, cause);
-
-        // Set __cause__.
-        Py_INCREF(cause);  // PyException_SetCause() steals a reference.
-        PyException_SetCause(exc, cause);
+    if (exc->name != NULL) {
+        if (exc->msg != NULL) {
+            PyErr_Format(wrapperclass, "%s: %s",  exc->name, exc->msg);
+        }
+        else {
+            PyErr_SetString(wrapperclass, exc->name);
+        }
+    }
+    else if (exc->msg != NULL) {
+        PyErr_SetString(wrapperclass, exc->msg);
+    }
+    else {
+        PyErr_SetNone(wrapperclass);
     }
-
-    return exc;
 }
 
 
@@ -2756,9 +1869,11 @@ _ensure_not_running(PyInterpreterState *interp)
 
 static int
 _run_script(PyInterpreterState *interp, const char *codestr,
-            _sharedns *shared, _sharedexception **pexc)
+            _sharedns *shared, _sharedexception **exc)
 {
-    assert(!PyErr_Occurred());  // ...in the called interpreter.
+    PyObject *exctype = NULL;
+    PyObject *excval = NULL;
+    PyObject *tb = NULL;
 
     PyObject *main_mod = _PyInterpreterState_GetMainModule(interp);
     if (main_mod == NULL) {
@@ -2789,38 +1904,25 @@ _run_script(PyInterpreterState *interp, const char *codestr,
         Py_DECREF(result);  // We throw away the result.
     }
 
-    *pexc = NULL;
+    *exc = NULL;
     return 0;
 
-    PyObject *exctype = NULL, *exc = NULL, *tb = NULL;
 error:
-    PyErr_Fetch(&exctype, &exc, &tb);
-
-    // First normalize the exception.
-    PyErr_NormalizeException(&exctype, &exc, &tb);
-    assert(PyExceptionInstance_Check(exc));
-    if (tb != NULL) {
-        PyException_SetTraceback(exc, tb);
-    }
-
-    // Behave as though the exception was caught in this thread.
-    PyErr_SetExcInfo(exctype, exc, tb);  // Like entering "except" block.
+    PyErr_Fetch(&exctype, &excval, &tb);
 
-    // Serialize the exception.
-    _sharedexception *sharedexc = _sharedexception_new();
+    _sharedexception *sharedexc = _sharedexception_bind(exctype, excval, tb);
+    Py_XDECREF(exctype);
+    Py_XDECREF(excval);
+    Py_XDECREF(tb);
     if (sharedexc == NULL) {
-        IGNORE_FAILURE("script raised an uncaught exception");
-    } else {
-        _sharedexception_extract(sharedexc, exc);
+        fprintf(stderr, "RunFailedError: script raised an uncaught exception");
+        PyErr_Clear();
+        sharedexc = NULL;
+    }
+    else {
         assert(!PyErr_Occurred());
     }
-
-    // Clear the exception.
-    PyErr_SetExcInfo(NULL, NULL, NULL);  // Like leaving "except" block.
-    PyErr_Clear();  // Do not re-raise.
-
-    // "Return" the serialized exception.
-    *pexc = sharedexc;
+    *exc = sharedexc;
     return -1;
 }
 
@@ -2828,8 +1930,6 @@ static int
 _run_script_in_interpreter(PyInterpreterState *interp, const char *codestr,
                            PyObject *shareables)
 {
-    assert(!PyErr_Occurred());  // ...in the calling interpreter.
-
     if (_ensure_not_running(interp) < 0) {
         return -1;
     }
@@ -2863,8 +1963,8 @@ _run_script_in_interpreter(PyInterpreterState *interp, const char *codestr,
     }
 
     // Run the script.
-    _sharedexception *sharedexc = NULL;
-    int result = _run_script(interp, codestr, shared, &sharedexc);
+    _sharedexception *exc = NULL;
+    int result = _run_script(interp, codestr, shared, &exc);
 
     // Switch back.
     if (save_tstate != NULL) {
@@ -2873,14 +1973,9 @@ _run_script_in_interpreter(PyInterpreterState *interp, const char *codestr,
 #endif
 
     // Propagate any exception out to the caller.
-    if (sharedexc != NULL) {
-        assert(!PyErr_Occurred());
-        PyObject *exc = _sharedexception_resolve(sharedexc, RunFailedError);
-        // XXX This is not safe once interpreters no longer share allocators.
-        _sharedexception_free(sharedexc);
-        PyObject *exctype = (PyObject *)Py_TYPE(exc);
-        Py_INCREF(exctype);  // PyErr_Restore() steals a reference.
-        PyErr_Restore(exctype, exc, PyException_GetTraceback(exc));
+    if (exc != NULL) {
+        _sharedexception_apply(exc, RunFailedError);
+        _sharedexception_free(exc);
     }
     else if (result != 0) {
         // We were unable to allocate a shared exception.
diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
index cf6d7449ba..41baa45573 100644
--- a/Modules/clinic/posixmodule.c.h
+++ b/Modules/clinic/posixmodule.c.h
@@ -8388,18 +8388,24 @@ PyDoc_STRVAR(os_DirEntry_is_symlink__doc__,
 "Return True if the entry is a symbolic link; cached per entry.");
 
 #define OS_DIRENTRY_IS_SYMLINK_METHODDEF    \
-    {"is_symlink", (PyCFunction)os_DirEntry_is_symlink, METH_NOARGS, os_DirEntry_is_symlink__doc__},
+    {"is_symlink", (PyCFunction)(void(*)(void))os_DirEntry_is_symlink, METH_METHOD|METH_FASTCALL|METH_KEYWORDS, os_DirEntry_is_symlink__doc__},
 
 static int
-os_DirEntry_is_symlink_impl(DirEntry *self);
+os_DirEntry_is_symlink_impl(DirEntry *self, PyTypeObject *defining_class);
 
 static PyObject *
-os_DirEntry_is_symlink(DirEntry *self, PyObject *Py_UNUSED(ignored))
+os_DirEntry_is_symlink(DirEntry *self, PyTypeObject *defining_class, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
+    static const char * const _keywords[] = { NULL};
+    static _PyArg_Parser _parser = {":is_symlink", _keywords, 0};
     int _return_value;
 
-    _return_value = os_DirEntry_is_symlink_impl(self);
+    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser
+        )) {
+        goto exit;
+    }
+    _return_value = os_DirEntry_is_symlink_impl(self, defining_class);
     if ((_return_value == -1) && PyErr_Occurred()) {
         goto exit;
     }
@@ -8416,34 +8422,25 @@ PyDoc_STRVAR(os_DirEntry_stat__doc__,
 "Return stat_result object for the entry; cached per entry.");
 
 #define OS_DIRENTRY_STAT_METHODDEF    \
-    {"stat", (PyCFunction)(void(*)(void))os_DirEntry_stat, METH_FASTCALL|METH_KEYWORDS, os_DirEntry_stat__doc__},
+    {"stat", (PyCFunction)(void(*)(void))os_DirEntry_stat, METH_METHOD|METH_FASTCALL|METH_KEYWORDS, os_DirEntry_stat__doc__},
 
 static PyObject *
-os_DirEntry_stat_impl(DirEntry *self, int follow_symlinks);
+os_DirEntry_stat_impl(DirEntry *self, PyTypeObject *defining_class,
+                      int follow_symlinks);
 
 static PyObject *
-os_DirEntry_stat(DirEntry *self, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+os_DirEntry_stat(DirEntry *self, PyTypeObject *defining_class, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
     static const char * const _keywords[] = {"follow_symlinks", NULL};
-    static _PyArg_Parser _parser = {NULL, _keywords, "stat", 0};
-    PyObject *argsbuf[1];
-    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
+    static _PyArg_Parser _parser = {"|$p:stat", _keywords, 0};
     int follow_symlinks = 1;
 
-    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 0, 0, argsbuf);
-    if (!args) {
-        goto exit;
-    }
-    if (!noptargs) {
-        goto skip_optional_kwonly;
-    }
-    follow_symlinks = PyObject_IsTrue(args[0]);
-    if (follow_symlinks < 0) {
+    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
+        &follow_symlinks)) {
         goto exit;
     }
-skip_optional_kwonly:
-    return_value = os_DirEntry_stat_impl(self, follow_symlinks);
+    return_value = os_DirEntry_stat_impl(self, defining_class, follow_symlinks);
 
 exit:
     return return_value;
@@ -8456,35 +8453,26 @@ PyDoc_STRVAR(os_DirEntry_is_dir__doc__,
 "Return True if the entry is a directory; cached per entry.");
 
 #define OS_DIRENTRY_IS_DIR_METHODDEF    \
-    {"is_dir", (PyCFunction)(void(*)(void))os_DirEntry_is_dir, METH_FASTCALL|METH_KEYWORDS, os_DirEntry_is_dir__doc__},
+    {"is_dir", (PyCFunction)(void(*)(void))os_DirEntry_is_dir, METH_METHOD|METH_FASTCALL|METH_KEYWORDS, os_DirEntry_is_dir__doc__},
 
 static int
-os_DirEntry_is_dir_impl(DirEntry *self, int follow_symlinks);
+os_DirEntry_is_dir_impl(DirEntry *self, PyTypeObject *defining_class,
+                        int follow_symlinks);
 
 static PyObject *
-os_DirEntry_is_dir(DirEntry *self, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+os_DirEntry_is_dir(DirEntry *self, PyTypeObject *defining_class, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
     static const char * const _keywords[] = {"follow_symlinks", NULL};
-    static _PyArg_Parser _parser = {NULL, _keywords, "is_dir", 0};
-    PyObject *argsbuf[1];
-    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
+    static _PyArg_Parser _parser = {"|$p:is_dir", _keywords, 0};
     int follow_symlinks = 1;
     int _return_value;
 
-    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 0, 0, argsbuf);
-    if (!args) {
-        goto exit;
-    }
-    if (!noptargs) {
-        goto skip_optional_kwonly;
-    }
-    follow_symlinks = PyObject_IsTrue(args[0]);
-    if (follow_symlinks < 0) {
+    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
+        &follow_symlinks)) {
         goto exit;
     }
-skip_optional_kwonly:
-    _return_value = os_DirEntry_is_dir_impl(self, follow_symlinks);
+    _return_value = os_DirEntry_is_dir_impl(self, defining_class, follow_symlinks);
     if ((_return_value == -1) && PyErr_Occurred()) {
         goto exit;
     }
@@ -8501,35 +8489,26 @@ PyDoc_STRVAR(os_DirEntry_is_file__doc__,
 "Return True if the entry is a file; cached per entry.");
 
 #define OS_DIRENTRY_IS_FILE_METHODDEF    \
-    {"is_file", (PyCFunction)(void(*)(void))os_DirEntry_is_file, METH_FASTCALL|METH_KEYWORDS, os_DirEntry_is_file__doc__},
+    {"is_file", (PyCFunction)(void(*)(void))os_DirEntry_is_file, METH_METHOD|METH_FASTCALL|METH_KEYWORDS, os_DirEntry_is_file__doc__},
 
 static int
-os_DirEntry_is_file_impl(DirEntry *self, int follow_symlinks);
+os_DirEntry_is_file_impl(DirEntry *self, PyTypeObject *defining_class,
+                         int follow_symlinks);
 
 static PyObject *
-os_DirEntry_is_file(DirEntry *self, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+os_DirEntry_is_file(DirEntry *self, PyTypeObject *defining_class, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
     static const char * const _keywords[] = {"follow_symlinks", NULL};
-    static _PyArg_Parser _parser = {NULL, _keywords, "is_file", 0};
-    PyObject *argsbuf[1];
-    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
+    static _PyArg_Parser _parser = {"|$p:is_file", _keywords, 0};
     int follow_symlinks = 1;
     int _return_value;
 
-    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 0, 0, argsbuf);
-    if (!args) {
-        goto exit;
-    }
-    if (!noptargs) {
-        goto skip_optional_kwonly;
-    }
-    follow_symlinks = PyObject_IsTrue(args[0]);
-    if (follow_symlinks < 0) {
+    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
+        &follow_symlinks)) {
         goto exit;
     }
-skip_optional_kwonly:
-    _return_value = os_DirEntry_is_file_impl(self, follow_symlinks);
+    _return_value = os_DirEntry_is_file_impl(self, defining_class, follow_symlinks);
     if ((_return_value == -1) && PyErr_Occurred()) {
         goto exit;
     }
@@ -9417,4 +9396,4 @@ exit:
 #ifndef OS_WAITSTATUS_TO_EXITCODE_METHODDEF
     #define OS_WAITSTATUS_TO_EXITCODE_METHODDEF
 #endif /* !defined(OS_WAITSTATUS_TO_EXITCODE_METHODDEF) */
-/*[clinic end generated code: output=be90d3aba972098b input=a9049054013a1b77]*/
+/*[clinic end generated code: output=005919eaaef3f8e6 input=a9049054013a1b77]*/
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 60a60e9aed..2ddf30de89 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -2101,48 +2101,50 @@ statresult_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 static int
 _posix_clear(PyObject *module)
 {
-    Py_CLEAR(get_posix_state(module)->billion);
-    Py_CLEAR(get_posix_state(module)->DirEntryType);
-    Py_CLEAR(get_posix_state(module)->ScandirIteratorType);
+    _posixstate *state = get_posix_state(module);
+    Py_CLEAR(state->billion);
+    Py_CLEAR(state->DirEntryType);
+    Py_CLEAR(state->ScandirIteratorType);
 #if defined(HAVE_SCHED_SETPARAM) || defined(HAVE_SCHED_SETSCHEDULER) || defined(POSIX_SPAWN_SETSCHEDULER) || defined(POSIX_SPAWN_SETSCHEDPARAM)
-    Py_CLEAR(get_posix_state(module)->SchedParamType);
+    Py_CLEAR(state->SchedParamType);
 #endif
-    Py_CLEAR(get_posix_state(module)->StatResultType);
-    Py_CLEAR(get_posix_state(module)->StatVFSResultType);
-    Py_CLEAR(get_posix_state(module)->TerminalSizeType);
-    Py_CLEAR(get_posix_state(module)->TimesResultType);
-    Py_CLEAR(get_posix_state(module)->UnameResultType);
+    Py_CLEAR(state->StatResultType);
+    Py_CLEAR(state->StatVFSResultType);
+    Py_CLEAR(state->TerminalSizeType);
+    Py_CLEAR(state->TimesResultType);
+    Py_CLEAR(state->UnameResultType);
 #if defined(HAVE_WAITID) && !defined(__APPLE__)
-    Py_CLEAR(get_posix_state(module)->WaitidResultType);
+    Py_CLEAR(state->WaitidResultType);
 #endif
 #if defined(HAVE_WAIT3) || defined(HAVE_WAIT4)
-    Py_CLEAR(get_posix_state(module)->struct_rusage);
+    Py_CLEAR(state->struct_rusage);
 #endif
-    Py_CLEAR(get_posix_state(module)->st_mode);
+    Py_CLEAR(state->st_mode);
     return 0;
 }
 
 static int
 _posix_traverse(PyObject *module, visitproc visit, void *arg)
 {
-    Py_VISIT(get_posix_state(module)->billion);
-    Py_VISIT(get_posix_state(module)->DirEntryType);
-    Py_VISIT(get_posix_state(module)->ScandirIteratorType);
+    _posixstate *state = get_posix_state(module);
+    Py_VISIT(state->billion);
+    Py_VISIT(state->DirEntryType);
+    Py_VISIT(state->ScandirIteratorType);
 #if defined(HAVE_SCHED_SETPARAM) || defined(HAVE_SCHED_SETSCHEDULER) || defined(POSIX_SPAWN_SETSCHEDULER) || defined(POSIX_SPAWN_SETSCHEDPARAM)
-    Py_VISIT(get_posix_state(module)->SchedParamType);
+    Py_VISIT(state->SchedParamType);
 #endif
-    Py_VISIT(get_posix_state(module)->StatResultType);
-    Py_VISIT(get_posix_state(module)->StatVFSResultType);
-    Py_VISIT(get_posix_state(module)->TerminalSizeType);
-    Py_VISIT(get_posix_state(module)->TimesResultType);
-    Py_VISIT(get_posix_state(module)->UnameResultType);
+    Py_VISIT(state->StatResultType);
+    Py_VISIT(state->StatVFSResultType);
+    Py_VISIT(state->TerminalSizeType);
+    Py_VISIT(state->TimesResultType);
+    Py_VISIT(state->UnameResultType);
 #if defined(HAVE_WAITID) && !defined(__APPLE__)
-    Py_VISIT(get_posix_state(module)->WaitidResultType);
+    Py_VISIT(state->WaitidResultType);
 #endif
 #if defined(HAVE_WAIT3) || defined(HAVE_WAIT4)
-    Py_VISIT(get_posix_state(module)->struct_rusage);
+    Py_VISIT(state->struct_rusage);
 #endif
-    Py_VISIT(get_posix_state(module)->st_mode);
+    Py_VISIT(state->st_mode);
     return 0;
 }
 
@@ -12747,17 +12749,20 @@ DirEntry_dealloc(DirEntry *entry)
 
 /* Forward reference */
 static int
-DirEntry_test_mode(DirEntry *self, int follow_symlinks, unsigned short mode_bits);
+DirEntry_test_mode(PyTypeObject *defining_class, DirEntry *self,
+                   int follow_symlinks, unsigned short mode_bits);
 
 /*[clinic input]
 os.DirEntry.is_symlink -> bool
+    defining_class: defining_class
+    /
 
 Return True if the entry is a symbolic link; cached per entry.
 [clinic start generated code]*/
 
 static int
-os_DirEntry_is_symlink_impl(DirEntry *self)
-/*[clinic end generated code: output=42244667d7bcfc25 input=1605a1b4b96976c3]*/
+os_DirEntry_is_symlink_impl(DirEntry *self, PyTypeObject *defining_class)
+/*[clinic end generated code: output=293096d589b6d47c input=e9acc5ee4d511113]*/
 {
 #ifdef MS_WINDOWS
     return (self->win32_lstat.st_mode & S_IFMT) == S_IFLNK;
@@ -12766,21 +12771,15 @@ os_DirEntry_is_symlink_impl(DirEntry *self)
     if (self->d_type != DT_UNKNOWN)
         return self->d_type == DT_LNK;
     else
-        return DirEntry_test_mode(self, 0, S_IFLNK);
+        return DirEntry_test_mode(defining_class, self, 0, S_IFLNK);
 #else
     /* POSIX without d_type */
-    return DirEntry_test_mode(self, 0, S_IFLNK);
+    return DirEntry_test_mode(defining_class, self, 0, S_IFLNK);
 #endif
 }
 
-static inline PyObject*
-DirEntry_get_module(DirEntry *self)
-{
-    return PyType_GetModule(Py_TYPE(self));
-}
-
 static PyObject *
-DirEntry_fetch_stat(DirEntry *self, int follow_symlinks)
+DirEntry_fetch_stat(PyObject *module, DirEntry *self, int follow_symlinks)
 {
     int result;
     STRUCT_STAT st;
@@ -12816,18 +12815,18 @@ DirEntry_fetch_stat(DirEntry *self, int follow_symlinks)
     if (result != 0)
         return path_object_error(self->path);
 
-    return _pystat_fromstructstat(DirEntry_get_module(self), &st);
+    return _pystat_fromstructstat(module, &st);
 }
 
 static PyObject *
-DirEntry_get_lstat(DirEntry *self)
+DirEntry_get_lstat(PyTypeObject *defining_class, DirEntry *self)
 {
     if (!self->lstat) {
+        PyObject *module = PyType_GetModule(defining_class);
 #ifdef MS_WINDOWS
-        self->lstat = _pystat_fromstructstat(DirEntry_get_module(self),
-                                             &self->win32_lstat);
+        self->lstat = _pystat_fromstructstat(module, &self->win32_lstat);
 #else /* POSIX */
-        self->lstat = DirEntry_fetch_stat(self, 0);
+        self->lstat = DirEntry_fetch_stat(module, self, 0);
 #endif
     }
     Py_XINCREF(self->lstat);
@@ -12836,6 +12835,8 @@ DirEntry_get_lstat(DirEntry *self)
 
 /*[clinic input]
 os.DirEntry.stat
+    defining_class: defining_class
+    /
     *
     follow_symlinks: bool = True
 
@@ -12843,20 +12844,26 @@ Return stat_result object for the entry; cached per entry.
 [clinic start generated code]*/
 
 static PyObject *
-os_DirEntry_stat_impl(DirEntry *self, int follow_symlinks)
-/*[clinic end generated code: output=008593b3a6d01305 input=280d14c1d6f1d00d]*/
+os_DirEntry_stat_impl(DirEntry *self, PyTypeObject *defining_class,
+                      int follow_symlinks)
+/*[clinic end generated code: output=23f803e19c3e780e input=e816273c4e67ee98]*/
 {
-    if (!follow_symlinks)
-        return DirEntry_get_lstat(self);
+    if (!follow_symlinks) {
+        return DirEntry_get_lstat(defining_class, self);
+    }
 
     if (!self->stat) {
-        int result = os_DirEntry_is_symlink_impl(self);
-        if (result == -1)
+        int result = os_DirEntry_is_symlink_impl(self, defining_class);
+        if (result == -1) {
             return NULL;
-        else if (result)
-            self->stat = DirEntry_fetch_stat(self, 1);
-        else
-            self->stat = DirEntry_get_lstat(self);
+        }
+        if (result) {
+            PyObject *module = PyType_GetModule(defining_class);
+            self->stat = DirEntry_fetch_stat(module, self, 1);
+        }
+        else {
+            self->stat = DirEntry_get_lstat(defining_class, self);
+        }
     }
 
     Py_XINCREF(self->stat);
@@ -12865,7 +12872,8 @@ os_DirEntry_stat_impl(DirEntry *self, int follow_symlinks)
 
 /* Set exception and return -1 on error, 0 for False, 1 for True */
 static int
-DirEntry_test_mode(DirEntry *self, int follow_symlinks, unsigned short mode_bits)
+DirEntry_test_mode(PyTypeObject *defining_class, DirEntry *self,
+                   int follow_symlinks, unsigned short mode_bits)
 {
     PyObject *stat = NULL;
     PyObject *st_mode = NULL;
@@ -12890,7 +12898,7 @@ DirEntry_test_mode(DirEntry *self, int follow_symlinks, unsigned short mode_bits
 #if defined(MS_WINDOWS) || defined(HAVE_DIRENT_D_TYPE)
     if (need_stat) {
 #endif
-        stat = os_DirEntry_stat_impl(self, follow_symlinks);
+        stat = os_DirEntry_stat_impl(self, defining_class, follow_symlinks);
         if (!stat) {
             if (PyErr_ExceptionMatches(PyExc_FileNotFoundError)) {
                 /* If file doesn't exist (anymore), then return False
@@ -12900,7 +12908,8 @@ DirEntry_test_mode(DirEntry *self, int follow_symlinks, unsigned short mode_bits
             }
             goto error;
         }
-        st_mode = PyObject_GetAttr(stat, get_posix_state(DirEntry_get_module(self))->st_mode);
+        _posixstate* state = get_posix_state(PyType_GetModule(defining_class));
+        st_mode = PyObject_GetAttr(stat, state->st_mode);
         if (!st_mode)
             goto error;
 
@@ -12943,6 +12952,8 @@ error:
 
 /*[clinic input]
 os.DirEntry.is_dir -> bool
+    defining_class: defining_class
+    /
     *
     follow_symlinks: bool = True
 
@@ -12950,14 +12961,17 @@ Return True if the entry is a directory; cached per entry.
 [clinic start generated code]*/
 
 static int
-os_DirEntry_is_dir_impl(DirEntry *self, int follow_symlinks)
-/*[clinic end generated code: output=ad2e8d54365da287 input=0135232766f53f58]*/
+os_DirEntry_is_dir_impl(DirEntry *self, PyTypeObject *defining_class,
+                        int follow_symlinks)
+/*[clinic end generated code: output=0cd453b9c0987fdf input=1a4ffd6dec9920cb]*/
 {
-    return DirEntry_test_mode(self, follow_symlinks, S_IFDIR);
+    return DirEntry_test_mode(defining_class, self, follow_symlinks, S_IFDIR);
 }
 
 /*[clinic input]
 os.DirEntry.is_file -> bool
+    defining_class: defining_class
+    /
     *
     follow_symlinks: bool = True
 
@@ -12965,10 +12979,11 @@ Return True if the entry is a file; cached per entry.
 [clinic start generated code]*/
 
 static int
-os_DirEntry_is_file_impl(DirEntry *self, int follow_symlinks)
-/*[clinic end generated code: output=8462ade481d8a476 input=0dc90be168b041ee]*/
+os_DirEntry_is_file_impl(DirEntry *self, PyTypeObject *defining_class,
+                         int follow_symlinks)
+/*[clinic end generated code: output=f7c277ab5ba80908 input=0a64c5a12e802e3b]*/
 {
-    return DirEntry_test_mode(self, follow_symlinks, S_IFREG);
+    return DirEntry_test_mode(defining_class, self, follow_symlinks, S_IFREG);
 }
 
 /*[clinic input]
@@ -13496,6 +13511,8 @@ static PyType_Spec ScandirIteratorType_spec = {
     MODNAME ".ScandirIterator",
     sizeof(ScandirIterator),
     0,
+    // bpo-40549: Py_TPFLAGS_BASETYPE should not be used, since
+    // PyType_GetModule(Py_TYPE(self)) doesn't work on a subclass instance.
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_FINALIZE,
     ScandirIteratorType_slots
 };
@@ -14785,12 +14802,10 @@ static const char * const have_functions[] = {
 static int
 posixmodule_exec(PyObject *m)
 {
-    PyObject *v;
-    PyObject *list;
-    const char * const *trace;
+    _posixstate *state = get_posix_state(m);
 
     /* Initialize environ dictionary */
-    v = convertenviron();
+    PyObject *v = convertenviron();
     Py_XINCREF(v);
     if (v == NULL || PyModule_AddObject(m, "environ", v) != 0)
         return -1;
@@ -14813,7 +14828,7 @@ posixmodule_exec(PyObject *m)
     }
     Py_INCREF(WaitidResultType);
     PyModule_AddObject(m, "waitid_result", WaitidResultType);
-    get_posix_state(m)->WaitidResultType = WaitidResultType;
+    state->WaitidResultType = WaitidResultType;
 #endif
 
     stat_result_desc.name = "os.stat_result"; /* see issue #19209 */
@@ -14826,7 +14841,7 @@ posixmodule_exec(PyObject *m)
     }
     Py_INCREF(StatResultType);
     PyModule_AddObject(m, "stat_result", StatResultType);
-    get_posix_state(m)->StatResultType = StatResultType;
+    state->StatResultType = StatResultType;
     structseq_new = ((PyTypeObject *)StatResultType)->tp_new;
     ((PyTypeObject *)StatResultType)->tp_new = statresult_new;
 
@@ -14837,7 +14852,7 @@ posixmodule_exec(PyObject *m)
     }
     Py_INCREF(StatVFSResultType);
     PyModule_AddObject(m, "statvfs_result", StatVFSResultType);
-    get_posix_state(m)->StatVFSResultType = StatVFSResultType;
+    state->StatVFSResultType = StatVFSResultType;
 #ifdef NEED_TICKS_PER_SECOND
 #  if defined(HAVE_SYSCONF) && defined(_SC_CLK_TCK)
     ticks_per_second = sysconf(_SC_CLK_TCK);
@@ -14856,7 +14871,7 @@ posixmodule_exec(PyObject *m)
     }
     Py_INCREF(SchedParamType);
     PyModule_AddObject(m, "sched_param", SchedParamType);
-    get_posix_state(m)->SchedParamType = SchedParamType;
+    state->SchedParamType = SchedParamType;
     ((PyTypeObject *)SchedParamType)->tp_new = os_sched_param;
 #endif
 
@@ -14867,14 +14882,14 @@ posixmodule_exec(PyObject *m)
     }
     Py_INCREF(TerminalSizeType);
     PyModule_AddObject(m, "terminal_size", TerminalSizeType);
-    get_posix_state(m)->TerminalSizeType = TerminalSizeType;
+    state->TerminalSizeType = TerminalSizeType;
 
     /* initialize scandir types */
     PyObject *ScandirIteratorType = PyType_FromModuleAndSpec(m, &ScandirIteratorType_spec, NULL);
     if (ScandirIteratorType == NULL) {
         return -1;
     }
-    get_posix_state(m)->ScandirIteratorType = ScandirIteratorType;
+    state->ScandirIteratorType = ScandirIteratorType;
 
     PyObject *DirEntryType = PyType_FromModuleAndSpec(m, &DirEntryType_spec, NULL);
     if (DirEntryType == NULL) {
@@ -14882,7 +14897,7 @@ posixmodule_exec(PyObject *m)
     }
     Py_INCREF(DirEntryType);
     PyModule_AddObject(m, "DirEntry", DirEntryType);
-    get_posix_state(m)->DirEntryType = DirEntryType;
+    state->DirEntryType = DirEntryType;
 
     times_result_desc.name = MODNAME ".times_result";
     PyObject *TimesResultType = (PyObject *)PyStructSequence_NewType(&times_result_desc);
@@ -14891,7 +14906,7 @@ posixmodule_exec(PyObject *m)
     }
     Py_INCREF(TimesResultType);
     PyModule_AddObject(m, "times_result", TimesResultType);
-    get_posix_state(m)->TimesResultType = TimesResultType;
+    state->TimesResultType = TimesResultType;
 
     PyTypeObject *UnameResultType = PyStructSequence_NewType(&uname_result_desc);
     if (UnameResultType == NULL) {
@@ -14899,7 +14914,7 @@ posixmodule_exec(PyObject *m)
     }
     Py_INCREF(UnameResultType);
     PyModule_AddObject(m, "uname_result", (PyObject *)UnameResultType);
-    get_posix_state(m)->UnameResultType = (PyObject *)UnameResultType;
+    state->UnameResultType = (PyObject *)UnameResultType;
 
 #ifdef __APPLE__
     /*
@@ -14939,15 +14954,15 @@ posixmodule_exec(PyObject *m)
 
 #endif /* __APPLE__ */
 
-    if ((get_posix_state(m)->billion = PyLong_FromLong(1000000000)) == NULL)
+    if ((state->billion = PyLong_FromLong(1000000000)) == NULL)
         return -1;
 #if defined(HAVE_WAIT3) || defined(HAVE_WAIT4)
-    get_posix_state(m)->struct_rusage = PyUnicode_InternFromString("struct_rusage");
-    if (get_posix_state(m)->struct_rusage == NULL)
+    state->struct_rusage = PyUnicode_InternFromString("struct_rusage");
+    if (state->struct_rusage == NULL)
         return -1;
 #endif
-    get_posix_state(m)->st_mode = PyUnicode_InternFromString("st_mode");
-    if (get_posix_state(m)->st_mode == NULL)
+    state->st_mode = PyUnicode_InternFromString("st_mode");
+    if (state->st_mode == NULL)
         return -1;
 
     /* suppress "function not used" warnings */
@@ -14964,10 +14979,11 @@ posixmodule_exec(PyObject *m)
      * provide list of locally available functions
      * so os.py can populate support_* lists
      */
-    list = PyList_New(0);
-    if (!list)
+    PyObject *list = PyList_New(0);
+    if (!list) {
         return -1;
-    for (trace = have_functions; *trace; trace++) {
+    }
+    for (const char * const *trace = have_functions; *trace; trace++) {
         PyObject *unicode = PyUnicode_DecodeASCII(*trace, strlen(*trace), NULL);
         if (!unicode)
             return -1;