aio-libs / multidict / 35603248557

87%

push

github

Drop -I from the ASan test command so PYTHONMALLOC takes effect (#1499)

<!-- Thank you for your contribution! -->

## What do these changes do?

The ASan test command in `AGENTS.md` and in the CI `asan` job ran
`python -Im pytest` with `PYTHONMALLOC=malloc`. `-I` implies `-E`, so
Python ignored `PYTHONMALLOC` and kept serving small allocations from
pymalloc arenas. Most `htkeys_t` tables are 512 bytes or less, so ASan
could not detect use-after-free on them. This drops `-I` in both places
and adds a short note explaining why it must stay out. The TSan command
and job, and the `Makefile`, do not combine `-I`/`-E` with
`PYTHONMALLOC` and are unchanged.

## Are there changes in behavior for the user?

No. Contributor-facing only.

## Is it a substantial burden for the maintainers to support this?

No.

## Related issue number

N/A

## Checklist

- [x] I think the code is well written
- [ ] Unit tests for the changes exist: N/A, docs and CI invocation only
- [x] Documentation reflects the changes
- [ ] If you provide code modification, please add yourself to
`CONTRIBUTORS.txt`: N/A
- [x] Add a new news fragment into the `CHANGES/` folder
- [x] `make doc-spelling` passes and any new technical words are added
to `docs/spelling_wordlist.txt`

Drafted with Claude Opus 5 (Claude Code); reviewed by @asvetlov.

<details>
<summary>Agent run details (optional, for reviewers)</summary>

Allocator check on CPython 3.13.2: `PYTHONMALLOC=malloc python -c
...pymem_getallocatorsname()` reports `malloc`; with `-I` it reports
`pymalloc`.

Earlier manual check:
`tests/test_multidict.py::test_items_iter_key_str_reinits` (from #1496)
hits a heap-use-after-free on the pre-fix code under `python -m pytest`,
but passes under `python -Im pytest`.

Corrected command on current master, ASan+UBSan build, isolated 3.13.2
venv: `LD_PRELOAD=$ASAN_SO ASAN_OPTIONS=detect_leaks=0:halt_on_error=1
PYTHONMALLOC=malloc python -m pytest tests -q --no-cov -k "not
test_leak"` gave 2048 passed,... (continued)

762 of 1524 branches covered (50.0%)

Branch coverage included in aggregate %.

6455 of 6727 relevant lines covered (95.96%)

1.92 hits per line