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Fix for async drop inside async gen fn#141932

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azhogin:azhogin/async-drop-inside-asyncgen-fix
Jun 5, 2025
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Fix for async drop inside async gen fn#141932
bors merged 1 commit intorust-lang:masterfrom
azhogin:azhogin/async-drop-inside-asyncgen-fix

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@azhogin azhogin commented Jun 2, 2025 •
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Return value (for yield) is corrected for async drop inside async gen function.
In CFG, when internal async drop future is polled and returned Poll<()>::Pending, then async gen resume function returns Poll<(OptRet)>::Pending.

Fixes #140530

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rustbot commented Jun 2, 2025

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rustbot commented Jun 2, 2025

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jun 2, 2025
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azhogin commented Jun 2, 2025

r? oli-obk

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@azhogin azhogin force-pushed the azhogin/async-drop-inside-asyncgen-fix branch from 8e0c3d0 to 8e20c56 Compare June 2, 2025 21:08
oli-obk
oli-obk reviewed Jun 3, 2025
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compiler/rustc_mir_transform/src/coroutine.rs Outdated
Comment on lines 327 to 328
// yield (const false) is used for async drop yields inside AsyncGen
// We need to convert value to Poll<OptRet>::Pending
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Can we directly generate the right yield in the async drop logic?

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@azhogin azhogin Jun 3, 2025

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TerminatorKind::Yield value is Operand, but we need Rvalue::Aggregate (make_aggregate_adt).

As far as I understand, we can do Operand with an additional local variable.
So, instead of 'return Poll::Pending;', the generated code will be 'x = Poll::Pending; return x;'

Value for Yield is generated here:

rust/compiler/rustc_mir_transform/src/coroutine/drop.rs

Line 386 in b17dba4

let value = Operand::Constant(Box::new(ConstOperand {
.

Does it cost additional temporary local?

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We can generate a const operand directly for a value of Poll::Pending(()), so that would not be the issue.

@azhogin azhogin force-pushed the azhogin/async-drop-inside-asyncgen-fix branch from 8e20c56 to d5a9a00 Compare June 4, 2025 11:45
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oli-obk commented Jun 4, 2025

Oh heh that works, nice

@bors r+ rollup

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bors commented Jun 4, 2025

📌 Commit d5a9a00 has been approved by oli-obk

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 4, 2025
@matthiaskrgr matthiaskrgr mentioned this pull request Jun 4, 2025
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bors added a commit that referenced this pull request Jun 5, 2025
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Auto merge of #142033 - matthiaskrgr:rollup-99lvg0j, r=matthiaskrgr
81a964c 
Rollup of 11 pull requests

Successful merges:

 - #141890 (Add link to correct documentation in htmldocck.py)
 - #141932 (Fix for async drop inside async gen fn)
 - #141960 (Use non-2015 edition paths in tests that do not test for their resolution)
 - #141968 (Run wfcheck in one big loop instead of per module)
 - #141969 (Triagebot: Remove `assign.users_on_vacation`)
 - #141985 (Ensure query keys are printed with reduced queries)
 - #141999 (Visit the ident in `PreciseCapturingNonLifetimeArg`.)
 - #142005 (Change `tag_field` to `FieldIdx` in `Variants::Multiple`)
 - #142017 (Fix incorrect use of "recommend" over "recommended")
 - #142024 (Don't refer to 'this tail expression' in expansion.)
 - #142025 (Don't refer to 'local binding' in extern macro.)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 9ec41bc into rust-lang:master Jun 5, 2025
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@rustbot rustbot added this to the 1.89.0 milestone Jun 5, 2025
rust-timer added a commit that referenced this pull request Jun 5, 2025
@rust-timer
Unrolled build for #141932
a323f18 
Rollup merge of #141932 - azhogin:azhogin/async-drop-inside-asyncgen-fix, r=oli-obk

Fix for async drop inside async gen fn

Return value (for yield) is corrected for async drop inside async gen function.
In CFG, when internal async drop future is polled and returned `Poll<()>::Pending`, then async gen resume function returns `Poll<(OptRet)>::Pending`.

Fixes #140530
@petrochenkov petrochenkov added the F-async_drop `#![feature(async_drop)]` label Jun 6, 2025
christian-schilling pushed a commit to christian-schilling/rustc_codegen_cranelift that referenced this pull request Jan 27, 2026
@bors
Auto merge of #142033 - matthiaskrgr:rollup-99lvg0j, r=matthiaskrgr
bd1ff92 
Rollup of 11 pull requests

Successful merges:

 - rust-lang/rust#141890 (Add link to correct documentation in htmldocck.py)
 - rust-lang/rust#141932 (Fix for async drop inside async gen fn)
 - rust-lang/rust#141960 (Use non-2015 edition paths in tests that do not test for their resolution)
 - rust-lang/rust#141968 (Run wfcheck in one big loop instead of per module)
 - rust-lang/rust#141969 (Triagebot: Remove `assign.users_on_vacation`)
 - rust-lang/rust#141985 (Ensure query keys are printed with reduced queries)
 - rust-lang/rust#141999 (Visit the ident in `PreciseCapturingNonLifetimeArg`.)
 - rust-lang/rust#142005 (Change `tag_field` to `FieldIdx` in `Variants::Multiple`)
 - rust-lang/rust#142017 (Fix incorrect use of "recommend" over "recommended")
 - rust-lang/rust#142024 (Don't refer to 'this tail expression' in expansion.)
 - rust-lang/rust#142025 (Don't refer to 'local binding' in extern macro.)

r? `@ghost`
`@rustbot` modify labels: rollup
christian-schilling pushed a commit to christian-schilling/rustc_codegen_cranelift that referenced this pull request Jan 27, 2026
@bors
Auto merge of #142033 - matthiaskrgr:rollup-99lvg0j, r=matthiaskrgr
99c29ec 
Rollup of 11 pull requests

Successful merges:

 - rust-lang/rust#141890 (Add link to correct documentation in htmldocck.py)
 - rust-lang/rust#141932 (Fix for async drop inside async gen fn)
 - rust-lang/rust#141960 (Use non-2015 edition paths in tests that do not test for their resolution)
 - rust-lang/rust#141968 (Run wfcheck in one big loop instead of per module)
 - rust-lang/rust#141969 (Triagebot: Remove `assign.users_on_vacation`)
 - rust-lang/rust#141985 (Ensure query keys are printed with reduced queries)
 - rust-lang/rust#141999 (Visit the ident in `PreciseCapturingNonLifetimeArg`.)
 - rust-lang/rust#142005 (Change `tag_field` to `FieldIdx` in `Variants::Multiple`)
 - rust-lang/rust#142017 (Fix incorrect use of "recommend" over "recommended")
 - rust-lang/rust#142024 (Don't refer to 'this tail expression' in expansion.)
 - rust-lang/rust#142025 (Don't refer to 'local binding' in extern macro.)

r? `@ghost`
`@rustbot` modify labels: rollup
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F-async_drop `#![feature(async_drop)]` S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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