Pyerr value bound

[LilyFoote]

Implements more of the Bound api from #3684.

Follows on from #3819.

[codspeed-hq]

CodSpeed Performance Report

Merging #3820 will degrade performances by 15.02%

_{Comparing LilyFoote:pyerr-value-bound (bb1701b) with main (c24478e)}

Summary

⚡ 1 improvements
❌ 2 regressions
✅ 76 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	LilyFoote:pyerr-value-bound	Change
❌	list_via_downcast	157.2 ns	185 ns	-15.02%
⚡	not_a_list_via_downcast	244.4 ns	216.7 ns	+12.82%
❌	sequence_from_tuple	232.8 ns	260.6 ns	-10.66%

[davidhewitt]

Thanks so much for continuing onto this and also the follow-on in #3826 .

I'll hold off on reviewing this just until it's rebased post merge of #3819. (I also have quite a few things I'm trying to finish up this evening...)

[davidhewitt]

Thanks again for picking this one up!

Quite a few comments here, mostly related to removing .clone() to avoid the reference counting cycles when we can, for efficiency wins 😄

[davidhewitt]

Whew, getting there, thanks for the iterations! This one has turned out to be quite fiddly.

I think the biggest thing remaining is whether from_value_bound should just take Bound instead of &Bound; I think if you agree with that idea then it'll lead to a few more changes 🙈

[davidhewitt]

I think we're there! There's just a few stylistic nits, and then let's merge this. Thank you for the several rounds of iteration on this one; turned out to have quite a few design points!

[davidhewitt]

🚀