Invalid suggestion to .await on a function argument pattern #126903
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theemathas
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SparkyPotato
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Jun 24, 2024
compiler-errors
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…r-errors Don't suggest awaiting in closure patterns Fixes rust-lang#126903. For ```rust async fn do_async() {} fn main() { Some(do_async()).map(|()| {}); } ``` the error is now ```rust error[E0308]: mismatched types --> src/main.rs:4:27 | 4 | Some(do_async()).map(|()| {}); | ^^ | | | expected future, found `()` | expected due to this | = note: expected opaque type `impl Future<Output = ()>` found unit type `()` ``` Ideally, if `main` were to be `async`, it should be ```rs error[E0308]: mismatched types --> src/main.rs:4:27 | 4 | Some(do_async()).map(|()| {}); | ^^ | | | expected future, found `()` | expected due to this | = note: expected opaque type `impl Future<Output = ()>` found unit type `()` help: consider `await`ing on the `Future` | 4 | Some(do_async().await).map(|()| {}); | ++++++ ``` However, this would mean `FnCtx::check_pat_top` would have to be called with an `origin_expr` in `rustc_hir_typeck::check::check_fn`, and that expr would have to be somehow plumbed through `FnCtxt::check_expr_closure` and closure signature deduction. I'm willing to work on the plumbing but unsure how to start.
workingjubilee
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Jun 25, 2024
…r-errors Don't suggest awaiting in closure patterns Fixes rust-lang#126903. For ```rust async fn do_async() {} fn main() { Some(do_async()).map(|()| {}); } ``` the error is now ```rust error[E0308]: mismatched types --> src/main.rs:4:27 | 4 | Some(do_async()).map(|()| {}); | ^^ | | | expected future, found `()` | expected due to this | = note: expected opaque type `impl Future<Output = ()>` found unit type `()` ``` Ideally, if `main` were to be `async`, it should be ```rs error[E0308]: mismatched types --> src/main.rs:4:27 | 4 | Some(do_async()).map(|()| {}); | ^^ | | | expected future, found `()` | expected due to this | = note: expected opaque type `impl Future<Output = ()>` found unit type `()` help: consider `await`ing on the `Future` | 4 | Some(do_async().await).map(|()| {}); | ++++++ ``` However, this would mean `FnCtx::check_pat_top` would have to be called with an `origin_expr` in `rustc_hir_typeck::check::check_fn`, and that expr would have to be somehow plumbed through `FnCtxt::check_expr_closure` and closure signature deduction. I'm willing to work on the plumbing but unsure how to start.
rust-timer
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Jun 26, 2024
Rollup merge of rust-lang#126915 - SparkyPotato:fix-126903, r=compiler-errors Don't suggest awaiting in closure patterns Fixes rust-lang#126903. For ```rust async fn do_async() {} fn main() { Some(do_async()).map(|()| {}); } ``` the error is now ```rust error[E0308]: mismatched types --> src/main.rs:4:27 | 4 | Some(do_async()).map(|()| {}); | ^^ | | | expected future, found `()` | expected due to this | = note: expected opaque type `impl Future<Output = ()>` found unit type `()` ``` Ideally, if `main` were to be `async`, it should be ```rs error[E0308]: mismatched types --> src/main.rs:4:27 | 4 | Some(do_async()).map(|()| {}); | ^^ | | | expected future, found `()` | expected due to this | = note: expected opaque type `impl Future<Output = ()>` found unit type `()` help: consider `await`ing on the `Future` | 4 | Some(do_async().await).map(|()| {}); | ++++++ ``` However, this would mean `FnCtx::check_pat_top` would have to be called with an `origin_expr` in `rustc_hir_typeck::check::check_fn`, and that expr would have to be somehow plumbed through `FnCtxt::check_expr_closure` and closure signature deduction. I'm willing to work on the plumbing but unsure how to start.
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Code
Current output
Desired output
Don't suggest awaiting.Rationale and extra context
No response
Other cases
No response
Rust Version
Playground's stable rust (1.79.0)Anything else?
Found by 0xbadbeef_60104 on the official rust discord.
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