aio-libs / multidict / 36312574728

86%

push

github

Build the C extension with -Wconversion actually enabled (#1611)

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

## What do these changes do?

`setup.py` passed `-Wconversion` followed by `-Wno-conversion`, so the
later flag won and conversion warnings were never reported. This drops
`-Wno-conversion` and adds the explicit casts the check then requires
across `htkeys.h`, `hashtable.h`, `bulk_update.h` and `identity.h`.
`tools/codegen_diff.py` against the merge base reports 0 changed
functions for the casts on both a GIL (3.13) and an FT (3.14t) build.
The optional Cython test module keeps building without `-Wconversion`,
since its generated code includes CPython's internal headers, which do
not pass it.

The check also found one real truncation: the items view `__contains__`
stored `PyObject_Length()` of a non-tuple, non-list operand in an `int`,
so a length of `2**32 + 2` read as 2 and the object was indexed as a
pair. It now uses the existing `Py_ssize_t len`. The pure-Python backend
rejects such operands up front and is unaffected.

## Are there changes in behavior for the user?

Only for the edge case above: `x in md.items()` returns `False` instead
of raising `TypeError` when `len(x)` is 2 modulo 2**32.

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

No. New code has to satisfy `-Wconversion` (including sign conversion
under GCC), which AGENTS.md already claimed was enforced.

## Related issue number

N/A

## Checklist

- [x] I think the code is well written
- [x] Unit tests for the changes exist
- [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 Code (Claude Opus 5.5); reviewed by @asvetlov.

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

Build: GC... (continued)

781 of 1562 branches covered (50.0%)

Branch coverage included in aggregate %.

7 of 7 new or added lines in 1 file covered. (100.0%)

8430 of 8999 relevant lines covered (93.68%)

1.87 hits per line