Streamline iterator chaining when computing successors. #148054
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There are numerous unnecessary `into_iter` calls. Also add a comment explaining why the code looks like this, because it's non-obvious at first glance.
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Huh. Neat. I agree that the iterator chaining thing is subtle, I was very confused by the type the first time I worked on this module. @bors r+ rollup |
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Rollup of 5 pull requests Successful merges: - #148016 (Revert constification of `Borrow` and `Deref for Cow` due to inference failure) - #148021 ([rustdoc] Simplify module rendering and HTML tags handling) - #148039 (Add myself to the review rotation) - #148042 (test(frontmatter): Cover spaces between infostring parts) - #148054 (Streamline iterator chaining when computing successors.) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of #148054 - nnethercote:chain, r=saethlin Streamline iterator chaining when computing successors. There are numerous unnecessary `into_iter` calls. Also add a comment explaining why the code looks like this, because it's non-obvious at first glance. r? `@saethlin`
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Bors hasn't noticed that this was merged. @bors r- |
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This appears to have somehow caused a bunch of perf regressions: #148059 (comment) Assuming the regression is real and not some weird noise, the only possible explanation I can think of is that this PR does slightly change the shape of the iterator, and maybe that's enough to cause measurably worse codegen despite giving equivalent results? |
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There are numerous unnecessary
into_itercalls.Also add a comment explaining why the code looks like this, because it's non-obvious at first glance.
r? @saethlin