Avoid predecessors having Drop impls

[Mark-Simulacrum]

Should be a simple win - but let's make sure with perf.

[rust-highfive]

r? @jackh726

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[Mark-Simulacrum]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[bors]

⌛ Trying commit 0367e24 with merge e3407ab7a490155d6a4afa07bfc13c60b79aa1f1...

[bors]

☀️ Try build successful - checks-actions
Build commit: e3407ab7a490155d6a4afa07bfc13c60b79aa1f1 (e3407ab7a490155d6a4afa07bfc13c60b79aa1f1)

[rust-timer]

Queued e3407ab7a490155d6a4afa07bfc13c60b79aa1f1 with parent 467253f, future comparison URL.

[rust-timer]

Finished benchmarking try commit (e3407ab7a490155d6a4afa07bfc13c60b79aa1f1): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

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

[Mark-Simulacrum]

Seems like either a small improvement or almost no change, but also seems likely to have larger effects if we start calling predecessors more. Intuitively this should be a little better; I'm inclined to merge.

[jackh726]

@bors r+

[bors]

📌 Commit 0367e24 has been approved by jackh726

[bors]

⌛ Testing commit 0367e24 with merge ca82264...

[bors]

☀️ Test successful - checks-actions
Approved by: jackh726
Pushing ca82264 to master...