Description

ionite34

opened on Feb 13, 2023

Issue body actions

Bug report

If the callable of a callable iterator (with sentinel) exhausts the iterator itself during the call, a SystemError occurs.

Example discovered by @chilaxan

def bug():
    if bug.clear:
        return 1
    else:
        bug.clear = True
        list(bug.iterator)
        return 0

bug.iterator = iter(bug, 1)
bug.clear = False
next(bug.iterator)

SystemError: Objects\object.c:722: bad argument to internal function

Likely cause

iterobject.calliter_iternext does not check whether it->it_sentinel is NULL after the _PyObject_CallNoArgs call
https://github.com/python/cpython/blob/main/Objects/iterobject.c#L207-L237

static PyObject *
calliter_iternext(calliterobject *it)
{
    PyObject *result;

    if (it->it_callable == NULL) {
        return NULL;
    }

+   result = _PyObject_CallNoArgs(it->it_callable);
    if (result != NULL) {
        int ok;

+       ok = PyObject_RichCompareBool(it->it_sentinel, result, Py_EQ);
        if (ok == 0) {
            return result; /* Common case, fast path */
        }
(...)

Your environment

Appears to affect 3.7-3.12

Linked PRs

• gh-101892: Fix SystemError when a callable iterator call exhausts the iterator #101896
• [3.11] gh-101892: Fix SystemError when a callable iterator call exhausts the iterator (GH-101896) #102418
• [3.10] gh-101892: Fix SystemError when a callable iterator call exhausts the iterator (GH-101896) #102422

Activity

1. ionite34

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Feb 13, 2023
2. arhadthedev

   added

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   on Feb 14, 2023
3. kumaraditya303

   added a commit that references this issue on Mar 4, 2023

   gh-101892: Fix `SystemError` when a callable iterator call exhausts t…

   705487c
4. miss-islington

   added 2 commits that reference this issue on Mar 4, 2023

   pythongh-101892: Fix `SystemError` when a callable iterator call exha…

   1d07066

   gh-101892: Fix `SystemError` when a callable iterator call exhausts t…

   06a3bb8
5. arhadthedev

   added a commit that references this issue on Mar 4, 2023

   pythongh-101892: Fix `SystemError` when a callable iterator call exha…

   5573d36
6. kumaraditya303

   added a commit that references this issue on Mar 4, 2023

   [3.10] gh-101892: Fix `SystemError` when a callable iterator call exh…

   fe36778
7. kumaraditya303

   closed this as completedon Mar 4, 2023
8. hugovk

   added a commit that references this issue on Mar 6, 2023

   pythongh-101892: Fix `SystemError` when a callable iterator call exha…

   bf01a62
9. carljm

   added 2 commits that reference this issue on Mar 6, 2023

   Merge branch 'main' into nodeaddict

   33dda2a

   Merge branch 'main' into inlinecomp2

   ecb313c

Issue actions