Force the inner coroutine of an async closure to move if the outer closure is move and FnOnce
#125306
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…closure is `move` and `FnOnce`
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May 20, 2024
| // in a way that forces a move. See the test: | ||
| // `async-await/async-closures/force-move-due-to-inferred-kind.rs`. | ||
| // | ||
| // 2. If the coroutine-closure is forced to be `FnOnce` due to the way it |
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(2.) is the new addition here, since we were already doing (1.) since 55e4661.
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@bors r+ rollup great documentation! |
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…cy, r=oli-obk Force the inner coroutine of an async closure to `move` if the outer closure is `move` and `FnOnce` See the detailed comment in `upvar.rs`. Fixes rust-lang#124867. Fixes rust-lang#124487. r? oli-obk
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…iaskrgr Rollup of 7 pull requests Successful merges: - rust-lang#124227 (Make sure that the method resolution matches in `note_source_of_type_mismatch_constraint`) - rust-lang#124896 (miri: rename intrinsic_fallback_checks_ub to intrinsic_fallback_is_spec) - rust-lang#125015 (Pattern types: Prohibit generic args on const params) - rust-lang#125043 (reference type safety invariant docs: clarification) - rust-lang#125259 (An async closure may implement `FnMut`/`Fn` if it has no self-borrows) - rust-lang#125306 (Force the inner coroutine of an async closure to `move` if the outer closure is `move` and `FnOnce`) - rust-lang#125378 (remove tracing tree indent lines) r? `@ghost` `@rustbot` modify labels: rollup
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…cy, r=oli-obk Force the inner coroutine of an async closure to `move` if the outer closure is `move` and `FnOnce` See the detailed comment in `upvar.rs`. Fixes rust-lang#124867. Fixes rust-lang#124487. r? oli-obk
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Rollup of 7 pull requests Successful merges: - rust-lang#125043 (reference type safety invariant docs: clarification) - rust-lang#125306 (Force the inner coroutine of an async closure to `move` if the outer closure is `move` and `FnOnce`) - rust-lang#125355 (Use Backtrace::force_capture instead of Backtrace::capture in rustc_log) - rust-lang#125378 (remove tracing tree indent lines) - rust-lang#125391 (Minor serialize/span tweaks) - rust-lang#125395 (Remove unnecessary `.md` from the documentation sidebar) - rust-lang#125399 (Stop using `to_hir_binop` in codegen) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup of 7 pull requests Successful merges: - rust-lang#125043 (reference type safety invariant docs: clarification) - rust-lang#125306 (Force the inner coroutine of an async closure to `move` if the outer closure is `move` and `FnOnce`) - rust-lang#125355 (Use Backtrace::force_capture instead of Backtrace::capture in rustc_log) - rust-lang#125382 (rustdoc: rename `issue-\d+.rs` tests to have meaningful names (part 7)) - rust-lang#125391 (Minor serialize/span tweaks) - rust-lang#125395 (Remove unnecessary `.md` from the documentation sidebar) - rust-lang#125399 (Stop using `to_hir_binop` in codegen) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup of 7 pull requests Successful merges: - rust-lang#125043 (reference type safety invariant docs: clarification) - rust-lang#125306 (Force the inner coroutine of an async closure to `move` if the outer closure is `move` and `FnOnce`) - rust-lang#125355 (Use Backtrace::force_capture instead of Backtrace::capture in rustc_log) - rust-lang#125382 (rustdoc: rename `issue-\d+.rs` tests to have meaningful names (part 7)) - rust-lang#125391 (Minor serialize/span tweaks) - rust-lang#125395 (Remove unnecessary `.md` from the documentation sidebar) - rust-lang#125399 (Stop using `to_hir_binop` in codegen) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#125306 - compiler-errors:closure-incongruency, r=oli-obk Force the inner coroutine of an async closure to `move` if the outer closure is `move` and `FnOnce` See the detailed comment in `upvar.rs`. Fixes rust-lang#124867. Fixes rust-lang#124487. r? oli-obk
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…ce-move, r=BoxyUwU Skip over args when determining if async-closure's inner coroutine consumes its upvars rust-lang#125306 implements a strategy for when we have an `async move ||` async-closure that is inferred to be `async FnOnce`, it will force the inner coroutine to also be `move`, since we cannot borrow any upvars from the parent async-closure (since `FnOnce` is not lending): https://github.com/rust-lang/rust/blob/8e86c9567154dc5a9ada15ab196d23eae2bd7d89/compiler/rustc_hir_typeck/src/upvar.rs#L211-L229 However, when this strategy was implemented, it reused the `ExprUseVisitor` data from visiting the whole coroutine, which includes additional statements due to `async`-specific argument desugaring: https://github.com/rust-lang/rust/blob/8e86c9567154dc5a9ada15ab196d23eae2bd7d89/compiler/rustc_ast_lowering/src/item.rs#L1197-L1228 Well, it turns out that we don't care about these argument desugaring parameters, because arguments to the async-closure are not the *async-closure*'s captures -- they exist for only one invocation of the closure, and they're always consumed by construction (see the argument desugaring above), so they will force the coroutine's inferred kind to `FnOnce`. (Unless they're `Copy`, because we never consider `Copy` types to be consumed): https://github.com/rust-lang/rust/blob/8e86c9567154dc5a9ada15ab196d23eae2bd7d89/compiler/rustc_hir_typeck/src/expr_use_visitor.rs#L60-L66 However, since we *were* visiting these arg exprs, this resulted in us too-aggressively applying `move` to the inner coroutine, resulting in regressions. For example, this PR fixes rust-lang#128516. Fascinatingly, the note above about how we never consume `Copy` types is why this only regressed when the argument types weren't all `Copy`. I tried to leave some comments inline to make this more clear :)
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Rollup merge of rust-lang#128520 - compiler-errors:more-precisely-force-move, r=BoxyUwU Skip over args when determining if async-closure's inner coroutine consumes its upvars rust-lang#125306 implements a strategy for when we have an `async move ||` async-closure that is inferred to be `async FnOnce`, it will force the inner coroutine to also be `move`, since we cannot borrow any upvars from the parent async-closure (since `FnOnce` is not lending): https://github.com/rust-lang/rust/blob/8e86c9567154dc5a9ada15ab196d23eae2bd7d89/compiler/rustc_hir_typeck/src/upvar.rs#L211-L229 However, when this strategy was implemented, it reused the `ExprUseVisitor` data from visiting the whole coroutine, which includes additional statements due to `async`-specific argument desugaring: https://github.com/rust-lang/rust/blob/8e86c9567154dc5a9ada15ab196d23eae2bd7d89/compiler/rustc_ast_lowering/src/item.rs#L1197-L1228 Well, it turns out that we don't care about these argument desugaring parameters, because arguments to the async-closure are not the *async-closure*'s captures -- they exist for only one invocation of the closure, and they're always consumed by construction (see the argument desugaring above), so they will force the coroutine's inferred kind to `FnOnce`. (Unless they're `Copy`, because we never consider `Copy` types to be consumed): https://github.com/rust-lang/rust/blob/8e86c9567154dc5a9ada15ab196d23eae2bd7d89/compiler/rustc_hir_typeck/src/expr_use_visitor.rs#L60-L66 However, since we *were* visiting these arg exprs, this resulted in us too-aggressively applying `move` to the inner coroutine, resulting in regressions. For example, this PR fixes rust-lang#128516. Fascinatingly, the note above about how we never consume `Copy` types is why this only regressed when the argument types weren't all `Copy`. I tried to leave some comments inline to make this more clear :)
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See the detailed comment in
upvar.rs.Fixes #124867.
Fixes #124487.
r? oli-obk