inline next() on &mut Iterator impl

[the8472]

In #87431 I found that (&mut range).fold doesn't optimize well because the default impl for for fold on &mut Iterator doesn't inline next. In that particular case it was worked around by using try_fold which takes a &mut self instead of self.

Let's see if this can be fixed more broadly.

[rust-highfive]

r? @m-ou-se

(rust-highfive has picked a reviewer for you, use r? to override)

[the8472]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit a398b6b with merge eb61fdba9cf2f7d6351ac9958b767cff681af8fc...

[bors]

☀️ Try build successful - checks-actions
Build commit: eb61fdba9cf2f7d6351ac9958b767cff681af8fc (eb61fdba9cf2f7d6351ac9958b767cff681af8fc)

[rust-timer]

Queued eb61fdba9cf2f7d6351ac9958b767cff681af8fc with parent 6ae8912, future comparison URL.

[rust-timer]

Finished benchmarking commit (eb61fdba9cf2f7d6351ac9958b767cff681af8fc): comparison url.

Summary: This benchmark run did not return any relevant changes.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR led to changes in compiler perf.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf -perf-regression

[the8472]

This now addresses the FIXME from #87431 since #[inline] works just as well as the original workaround, without disturbing perf.

[m-ou-se]

Thanks!

@bors r+

[bors]

📌 Commit f1c588f has been approved by m-ou-se

[bors]

⌛ Testing commit f1c588f with merge 989cc355cd00e5b9b66575f8c30a9176d10dc2b5...

[bors]

💥 Test timed out

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[the8472]

That may have been due to sccache invalidation caused by the github runner upgrade. Let's wait and see how the next PR in the queue fares.

[the8472]

@bors retry

[bors]

⌛ Testing commit f1c588f with merge ef4b306...

[bors]

☀️ Test successful - checks-actions
Approved by: m-ou-se
Pushing ef4b306 to master...

[rust-timer]

Finished benchmarking commit (ef4b306): comparison url.

Summary: This benchmark run did not return any relevant changes.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression