LanguagesCEvidence
cp-fopen-hot — measured, still hint
Status
hint. Wall-clock JSONL: cp-fopen-hot.jsonl. Not corpus-triaged. The 2026-10-22 corpus verdict does not cover this slug.
Measurement
2000 opens of a one-byte file. After opens once and rewind/fgetc. This is syscall-bound, not a parse benchmark.
| role | case | median_ms | ops | ratio |
|---|---|---|---|---|
| after | fopen_once | 0.068000 | 2000 | 1 |
| before | fopen_each_iter | 28.792000 | 2000 | 423.413 |
The microbench shows a cost for this one shape. Default stays hint until the shape is corpus-triaged. This ratio is not a general speedup.
Unblock
Do not set the default to error from this file alone. A changing input, a cold path, or another ABI can erase the difference. Corpus triage is still required before any default change.