[ty] Gate protocol compatibility on member count

[charliermarsh]

Summary

This is a small optimization in the manner of 93a16bd. Codex reports that for protocol with a large number of members (Small), and then another with one more member (Big), and def check_i(value: Small) -> Big: return value repeated many times, we get a 39% speedup.

[astral-sh-bot]

Typing conformance results

No changes detected ✅

Current numbers

The percentage of diagnostics emitted that were expected errors held steady at 87.94%. The percentage of expected errors that received a diagnostic held steady at 83.36%. The number of fully passing files held steady at 79/133.

[astral-sh-bot]

Memory usage report

Memory usage unchanged ✅

[astral-sh-bot]

ecosystem-analyzer results

No diagnostic changes detected ✅

Full report with detailed diff (timing results)

[AlexWaygood]

If this fixes a case where we previously had pathological (or much worse) performance, can we add that case as a microbenchmark in a separate PR and then rebase this PR on top of that to see the performance improvement in CI?

If we don't add benchmarks for this kind of thing and the improvement isn't reflected in codspeed or the ecosystem-analyzer timings, I think it'll be very easy for us to accidentally regress on performance in the future

[charliermarsh]

Good call

[codspeed-hq]

Merging this PR will improve performance by 91.11%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
✅ 48 untouched benchmarks
⏩ 60 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	ty_micro[many_protocol_members_mismatch]	337 ms	176.4 ms	+91.11%

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_{Comparing charlie/member-count (0a460bb) with main (1ab0ba3)}

Footnotes

1. 60 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩