aio-libs / multidict / 38391036861

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Fold _md_del_identity() into md_del() (#1790)

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## What do these changes do?

Folds `_md_del_identity()`, the single-caller helper behind `del
d[key]`, into `md_del()` in `_multilib/hashtable.h`. A failed hash now
releases the identity and returns early, as in `md_replace()` after
#1788, with both error checks marked `UNLIKELY()` as #1791 did there.
The pure-Python backend has no equivalent helper and is unaffected.

The return value is still computed with an explicit `ret`: collapsing it
to `found > 0 ? 0 : -1` made GCC lay out `md_del()` differently and cost
GIL `del d[key]` 3 instructions per call (+1.0..1.2%). With `ret`,
callgrind shows no row moving by 0.2% or more on either build, and `del
d[key]` matches master exactly.

## Are there changes in behavior for the user?

No.

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

No; it removes a helper.

## Related issue number

N/A

## Checklist

- [x] I think the code is well written
- [ ] Unit tests for the changes exist: N/A, a refactor covered by the
existing suite
- [ ] Documentation reflects the changes: N/A
- [ ] 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`

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

Tests: `pytest -q` passed on 3.11.13 GIL C extension (4274 passed),
3.14.7t C extension (4255 passed), and 3.11.13 pure Python with
`MULTIDICT_NO_EXTENSIONS=1 --no-c-extensions` (1697 passed).
Inlining: `tools/check_inlining.py` ok on 3.14.7 and 3.14.7t.
Docs: `make doc-spelling` passed.
Callgrind: `benchmarks/callgrind_driver.py --include-multidict-only`,
3.14.7 and 3.14.7t, against master 6b62c220. The only other row past
0.2% is FT `update`, +/-0.22% in opposite directions for the two
classes, which does not rea... (continued)

842 of 1684 branches covered (50.0%)

Branch coverage included in aggregate %.

9799 of 10709 relevant lines covered (91.5%)

1.83 hits per line