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bpo-39829: Fix __len__() is called twice in list() constructor (GH-31816)

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(cherry picked from commit 2153daf0a0)

This patch fixes gh-87740 too.

Co-authored-by: Crowthebird <78076854+thatbirdguythatuknownot@users.noreply.github.com>
This commit is contained in:
Miss Islington (bot) 2022-05-17 21:16:58 -07:00 • committed by GitHub
parent add8820df8
commit 009aeb6bb6
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3 changed files with 14 additions and 17 deletions
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29
Objects/listobject.c
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@ -863,7 +863,6 @@ list_extend(PyListObject *self, PyObject *iterable)
PyObject *it; /* iter(v) */
Py_ssize_t m; /* size of self */
Py_ssize_t n; /* guess for size of iterable */
Py_ssize_t mn; /* m + n */
Py_ssize_t i;
PyObject *(*iternext)(PyObject *);
@ -887,7 +886,13 @@ list_extend(PyListObject *self, PyObject *iterable)
/* It should not be possible to allocate a list large enough to cause
an overflow on any relevant platform */
assert(m < PY_SSIZE_T_MAX - n);
if (list_resize(self, m + n) < 0) {
if (self->ob_item == NULL) {
if (list_preallocate_exact(self, n) < 0) {
return NULL;
}
Py_SET_SIZE(self, n);
}
else if (list_resize(self, m + n) < 0) {
Py_DECREF(iterable);
return NULL;
}
@ -926,10 +931,13 @@ list_extend(PyListObject *self, PyObject *iterable)
* eventually run out of memory during the loop.
*/
}
else if (self->ob_item == NULL) {
if (n && list_preallocate_exact(self, n) < 0)
goto error;
}
else {
mn = m + n;
/* Make room. */
if (list_resize(self, mn) < 0)
if (list_resize(self, m + n) < 0)
goto error;
/* Make the list sane again. */
Py_SET_SIZE(self, m);
@ -2717,19 +2725,6 @@ list___init___impl(PyListObject *self, PyObject *iterable)
(void)_list_clear(self);
}
if (iterable != NULL) {
if (_PyObject_HasLen(iterable)) {
Py_ssize_t iter_len = PyObject_Size(iterable);
if (iter_len == -1) {
if (!PyErr_ExceptionMatches(PyExc_TypeError)) {
return -1;
}
PyErr_Clear();
}
if (iter_len > 0 && self->ob_item == NULL
&& list_preallocate_exact(self, iter_len)) {
return -1;
}
}
PyObject *rv = list_extend(self, iterable);
if (rv == NULL)
return -1;