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Rollup merge of #126915 - SparkyPotato:fix-126903, r=compiler-errors

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Don't suggest awaiting in closure patterns

Fixes #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.
This commit is contained in:
Matthias Krüger 2024-06-25 18:03:01 +02:00 • committed by GitHub
commit dad39e8840
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3 changed files with 24 additions and 3 deletions
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6
compiler/rustc_infer/src/infer/error_reporting/suggest.rs
View file

@ -209,8 +209,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
}
(Some(ty), _) if self.same_type_modulo_infer(ty, exp_found.found) => match cause.code()
{
ObligationCauseCode::Pattern { span: Some(then_span), .. } => {
Some(ConsiderAddingAwait::FutureSugg { span: then_span.shrink_to_hi() })
ObligationCauseCode::Pattern { span: Some(then_span), origin_expr, .. } => {
origin_expr.then_some(ConsiderAddingAwait::FutureSugg {
span: then_span.shrink_to_hi(),
})
}
ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => {
let then_span = self.find_block_span_from_hir_id(*then_id);