https://github.com/python/cpython/commit/8ad6067bd4556afddc86004f8e350aa672fda217
commit: 8ad6067bd4556afddc86004f8e350aa672fda217
branch: main
author: Mark Shannon <[email protected]>
committer: markshannon <[email protected]>
date: 2024-07-08T14:20:13+01:00
summary:
GH-121012: Set index to -1 when list iterators become exhausted in tier 2
(GH-121483)
files:
A Misc/NEWS.d/next/Core and
Builtins/2024-07-08-10-31-08.gh-issue-121012.M5hHk-.rst
M Lib/test/test_list.py
M Python/bytecodes.c
M Python/executor_cases.c.h
diff --git a/Lib/test/test_list.py b/Lib/test/test_list.py
index 4d2d54705fc894..ad7accf2099f43 100644
--- a/Lib/test/test_list.py
+++ b/Lib/test/test_list.py
@@ -299,6 +299,15 @@ def __eq__(self, other):
lst = [X(), X()]
X() in lst
+ def test_tier2_invalidates_iterator(self):
+ # GH-121012
+ for _ in range(100):
+ a = [1, 2, 3]
+ it = iter(a)
+ for _ in it:
+ pass
+ a.append(4)
+ self.assertEqual(list(it), [])
if __name__ == "__main__":
unittest.main()
diff --git a/Misc/NEWS.d/next/Core and
Builtins/2024-07-08-10-31-08.gh-issue-121012.M5hHk-.rst b/Misc/NEWS.d/next/Core
and Builtins/2024-07-08-10-31-08.gh-issue-121012.M5hHk-.rst
new file mode 100644
index 00000000000000..7b04eb68b03752
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and
Builtins/2024-07-08-10-31-08.gh-issue-121012.M5hHk-.rst
@@ -0,0 +1,2 @@
+Tier 2 execution now ensures that list iterators remain exhausted, once they
+become exhausted.
diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index 76587a4f0dc695..84241c64ffae88 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -2967,7 +2967,10 @@ dummy_func(
assert(Py_TYPE(iter_o) == &PyListIter_Type);
PyListObject *seq = it->it_seq;
EXIT_IF(seq == NULL);
- EXIT_IF((size_t)it->it_index >= (size_t)PyList_GET_SIZE(seq));
+ if ((size_t)it->it_index >= (size_t)PyList_GET_SIZE(seq)) {
+ it->it_index = -1;
+ EXIT_IF(1);
+ }
}
op(_ITER_NEXT_LIST, (iter -- iter, next)) {
diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
index 3b999465aac815..8f6bc75b528d9b 100644
--- a/Python/executor_cases.c.h
+++ b/Python/executor_cases.c.h
@@ -3055,8 +3055,11 @@
JUMP_TO_JUMP_TARGET();
}
if ((size_t)it->it_index >= (size_t)PyList_GET_SIZE(seq)) {
- UOP_STAT_INC(uopcode, miss);
- JUMP_TO_JUMP_TARGET();
+ it->it_index = -1;
+ if (1) {
+ UOP_STAT_INC(uopcode, miss);
+ JUMP_TO_JUMP_TARGET();
+ }
}
break;
}
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