Implement needs_async_drop in rustc and optimize async drop glue

[zetanumbers]

This PR expands on #121801 and implements Ty::needs_async_drop which works almost exactly the same as Ty::needs_drop, which is needed for #123948.

Also made compiler's async drop code to look more like compiler's regular drop code, which enabled me to write an optimization where types which do not use AsyncDrop can simply forward async drop glue to drop_in_place. This made size of the async block from the async_drop test to decrease by 12%.

[rustbot]

r? @wesleywiser

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[rustbot]

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[bors]

☔ The latest upstream changes (presumably #125150) made this pull request unmergeable. Please resolve the merge conflicts.

[lcnr]

r? @oli-obk

[bors]

☔ The latest upstream changes (presumably #125335) made this pull request unmergeable. Please resolve the merge conflicts.

[oli-obk]

Please add some MIR tests or at least size tests for affected async drop glue examples (ideally before the commits of this PR, so we can see the effect of them on the tests)

[rustbot]

The Miri subtree was changed

cc @rust-lang/miri

[zetanumbers]

The Miri subtree was changed

Somehow rebase triggered this check again, but I didn't change anything there from the last time.

[zetanumbers]

Please add some MIR tests or at least size tests for affected async drop glue examples (ideally before the commits of this PR, so we can see the effect of them on the tests)

Yep, see the improvements in 74df792

Please don't be scared of these sizes tho 👀

[lqd]

The Miri subtree was changed

Somehow rebase triggered this check again, but I didn't change anything there from the last time.

it's this added test https://github.com/rust-lang/rust/pull/124662/files#diff-fae422507110acd4267c8af94b7552bd0ca7e0900015521f7e511160a05ea4a8

[bors]

☔ The latest upstream changes (presumably #125665) made this pull request unmergeable. Please resolve the merge conflicts.

[oli-obk]

@bors r+

[bors]

📌 Commit 4903cf4 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit 4903cf4 with merge 99cb42c...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 99cb42c to master...

[rust-timer]

Finished benchmarking commit (99cb42c): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

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Binary size

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Bootstrap: 668.018s -> 667.778s (-0.04%)
Artifact size: 318.82 MiB -> 318.79 MiB (-0.01%)