Prereq1 for async drop - drop & async_fut fields in Drop terminator

[azhogin]

This is subpart 1 PR of #123948, just for review purposes.

Added Option drop and async_fut fields in Drop terminator for use when Drop terminator is async drop.

drop field has the same meaning as drop field in Yield terminator. We need it because async drop is a hidden Yield, expanded into yield-point in StateTransform (later commits).

async_fut contains local for async drop future, generated by async_fut = async_drop_in_place(droppee) in drop elaboration (later commits).

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

Some changes occurred to the CTFE / Miri engine

cc @rust-lang/miri

This PR changes MIR

cc @oli-obk, @RalfJung, @JakobDegen, @davidtwco, @celinval, @vakaras

[RalfJung]

It might be worth also discussing async drop in the MirPhase docs. And if any new MIR phase restrictions are added, please make sure to update the MIR validator.

[azhogin]

Comment about async drops added in MirPhase:

///  - Async drops: after drop elaboration some drops may become async (`drop`, `async_fut` fields).
///    StateTransform pass will expand those async drops or reset to sync.

Could you, pls, be more specific about "update the MIR validator"? Async drop terminators live from ElaborateDrops to StateTransform pass in transition to MirPhase::Runtime(..). What MIR validator changes do you recommend?

[bors]

☔ The latest upstream changes (presumably #130724) made this pull request unmergeable. Please resolve the merge conflicts.

[davidtwco]

r? @nikomatsakis is going to look into this

[bors]

☔ The latest upstream changes (presumably #136751) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #137030) made this pull request unmergeable. Please resolve the merge conflicts.

[rust-log-analyzer]

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info: removing rustup binaries
info: rustup is uninstalled
##[group]Image checksum input
mingw-check-tidy
# We use the ghcr base image because ghcr doesn't have a rate limit
# and the mingw-check-tidy job doesn't cache docker images in CI.
FROM ghcr.io/rust-lang/ubuntu:22.04
ARG DEBIAN_FRONTEND=noninteractive
RUN apt-get update && apt-get install -y --no-install-recommends \
  g++ \
  make \
---

COPY host-x86_64/mingw-check/validate-toolstate.sh /scripts/
COPY host-x86_64/mingw-check/validate-error-codes.sh /scripts/

# NOTE: intentionally uses python2 for x.py so we can test it still works.
# validate-toolstate only runs in our CI, so it's ok for it to only support python3.
ENV SCRIPT TIDY_PRINT_DIFF=1 python2.7 ../x.py test \
           --stage 0 src/tools/tidy tidyselftest --extra-checks=py,cpp
# This file is autogenerated by pip-compile with Python 3.10
# by the following command:
#
#    pip-compile --allow-unsafe --generate-hashes reuse-requirements.in
---
#12 3.067 Building wheels for collected packages: reuse
#12 3.068   Building wheel for reuse (pyproject.toml): started
#12 3.283   Building wheel for reuse (pyproject.toml): finished with status 'done'
#12 3.284   Created wheel for reuse: filename=reuse-4.0.3-cp310-cp310-manylinux_2_35_x86_64.whl size=132720 sha256=0c2fd2aaf7b0bf8d6e131220aff14712a774c2ca462f3204d25460cbcf610b63
#12 3.284   Stored in directory: /tmp/pip-ephem-wheel-cache-4mte__nf/wheels/3d/8d/0a/e0fc6aba4494b28a967ab5eaf951c121d9c677958714e34532
#12 3.286 Installing collected packages: boolean-py, binaryornot, tomlkit, reuse, python-debian, markupsafe, license-expression, jinja2, chardet, attrs
#12 3.690 Successfully installed attrs-23.2.0 binaryornot-0.4.4 boolean-py-4.0 chardet-5.2.0 jinja2-3.1.4 license-expression-30.3.0 markupsafe-2.1.5 python-debian-0.1.49 reuse-4.0.3 tomlkit-0.13.0
#12 3.691 WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv
#12 4.228 Collecting virtualenv
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#12 4.270   Downloading virtualenv-20.29.2-py3-none-any.whl (4.3 MB)
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#12 4.405 Collecting distlib<1,>=0.3.7
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#12 4.449 Collecting platformdirs<5,>=3.9.1
#12 4.453   Downloading platformdirs-4.3.6-py3-none-any.whl (18 kB)
#12 4.492 Collecting filelock<4,>=3.12.2
#12 4.495   Downloading filelock-3.17.0-py3-none-any.whl (16 kB)
#12 4.577 Installing collected packages: distlib, platformdirs, filelock, virtualenv
#12 4.760 Successfully installed distlib-0.3.9 filelock-3.17.0 platformdirs-4.3.6 virtualenv-20.29.2
#12 DONE 4.8s

#13 [7/8] COPY host-x86_64/mingw-check/validate-toolstate.sh /scripts/
#13 DONE 0.0s
---
DirectMap4k:      137152 kB
DirectMap2M:     9299968 kB
DirectMap1G:     9437184 kB
##[endgroup]
Executing TIDY_PRINT_DIFF=1 python2.7 ../x.py test            --stage 0 src/tools/tidy tidyselftest --extra-checks=py,cpp
+ TIDY_PRINT_DIFF=1 python2.7 ../x.py test --stage 0 src/tools/tidy tidyselftest --extra-checks=py,cpp
    Finished `dev` profile [unoptimized] target(s) in 0.05s
##[endgroup]
WARN: currently no CI rustc builds have rustc debug assertions enabled. Please either set `rust.debug-assertions` to `false` if you want to use download CI rustc or set `rust.download-rustc` to `false`.
downloading https://static.rust-lang.org/dist/2025-02-18/rustfmt-nightly-x86_64-unknown-linux-gnu.tar.xz