Remove unneeded drop_in_place calls

[scottmcm]

Might as well pull this out from #144561 because this is still used in things like Vec::truncate where it'd be nice to allow it be removed if inlined enough to see that the type is Copy.

So long as perf says it's ok, at least 🤞

[rustbot]

r? @nnethercote

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[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[scottmcm]

@bors try @rust-timer queue

[rust-bors]

⌛ Trying commit 952f142 with merge 641adcb…

To cancel the try build, run the command @bors try cancel.

[rust-bors]

☀️ Try build successful (CI)
Build commit: 641adcb (641adcb8fe61a1a2f4cc317723476b9d171e2813, parent: 07b7dc90ee4df5815dbb91ef8e98cb93571230f5)

[rust-timer]

Finished benchmarking commit (641adcb): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

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

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results (secondary -2.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.4%	[-2.4%, -2.4%]	1
All ❌✅ (primary)	-	-	0

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 467.146s -> 468.977s (0.39%)
Artifact size: 377.00 MiB -> 377.01 MiB (0.00%)

[nnethercote]

Looks good. Feels like a brief explanatory comment mentioning the two cases would help, on the match. Or maybe the doc comment at the top of the file could be modified to mention the two cases?

r=me with that

[nnethercote]

@bors r+

[bors]

📌 Commit 4e81eca has been approved by nnethercote

It is now in the queue for this repository.