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Remove confusing 'while checking' note from opaque future type mismatches #107201

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merged 1 commit into from
Feb 2, 2023

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Maybe I'm just misinterpreting the wording of the note. The only value I can see in this note is that it points out where the async's opaque future is coming from, but the way it's doing it is misleading IMO.

For example:

note: while checking the return type of the `async fn`
  --> $DIR/dont-suggest-missing-await.rs:7:24
   |
LL | async fn make_u32() -> u32 {
   |                        ^^^ checked the `Output` of this `async fn`, found opaque type

We point at the type u32 in the HIR, but then say "found opaque type". We also say "while checking"... but we're typechecking a totally different function when we get this type mismatch!

r? @estebank but feel free to reassign and/or take your time reviewing this. I'd be inclined to also discuss reworking the presentation of this type mismatch to restore some of these labels in a way that makes it more clear what it's trying to point out.

@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 Jan 22, 2023
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@compiler-errors compiler-errors force-pushed the confusing-async-fn-note branch from c7be912 to a63f5dc Compare January 22, 2023 17:03
@estebank
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I'm not entirely convinced that removing the span is an unambiguous improvement, but the current output isn't great either.

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@estebank - I agree, but I think the current wording is bordering on actively confusing.

I'm open to suggestions for a wording, but getting it to fit into the existing machinery might be hard.

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I can't further review this now, but I think r=me.

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@bors r=estebank rollup

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bors commented Feb 1, 2023

📌 Commit a63f5dc has been approved by estebank

It is now in the queue for this repository.

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bors commented Feb 1, 2023

🌲 The tree is currently closed for pull requests below priority 50. This pull request will be tested once the tree is reopened.

@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 Feb 1, 2023
compiler-errors added a commit to compiler-errors/rust that referenced this pull request Feb 2, 2023
…-note, r=estebank

Remove confusing 'while checking' note from opaque future type mismatches

Maybe I'm just misinterpreting the wording of the note. The only value I can see in this note is that it points out where the async's opaque future is coming from, but the way it's doing it is misleading IMO.

For example:

```rust
note: while checking the return type of the `async fn`
  --> $DIR/dont-suggest-missing-await.rs:7:24
   |
LL | async fn make_u32() -> u32 {
   |                        ^^^ checked the `Output` of this `async fn`, found opaque type
```

We point at the type `u32` in the HIR, but then say "found opaque type". We also say "while checking"... but we're typechecking a totally different function when we get this type mismatch!

r? `@estebank` but feel free to reassign and/or take your time reviewing this. I'd be inclined to also discuss reworking the presentation of this type mismatch to restore some of these labels in a way that makes it more clear what it's trying to point out.
bors added a commit to rust-lang-ci/rust that referenced this pull request Feb 2, 2023
…iaskrgr

Rollup of 5 pull requests

Successful merges:

 - rust-lang#107201 (Remove confusing 'while checking' note from opaque future type mismatches)
 - rust-lang#107312 (Add Style Guide rules for let-else statements)
 - rust-lang#107488 (Fix syntax in `-Zunpretty-expanded` output for derived `PartialEq`.)
 - rust-lang#107531 (Inline CSS background images directly into the CSS)
 - rust-lang#107576 (Add proc-macro boilerplate to crt-static test)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 480c4a1 into rust-lang:master Feb 2, 2023
@rustbot rustbot added this to the 1.69.0 milestone Feb 2, 2023
@compiler-errors compiler-errors deleted the confusing-async-fn-note branch August 11, 2023 19:57
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5 participants