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Improve "associated type not found" diagnostics #115662

Merged
merged 2 commits into from
Sep 9, 2023
Merged

Improve "associated type not found" diagnostics #115662

merged 2 commits into from
Sep 9, 2023

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ShE3py
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@ShE3py ShE3py commented Sep 8, 2023 •
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use core::ops::Deref;

fn foo<T>() where T: Deref<Output = u32> {}

Before:

error[E0220]: associated type `Output` not found for `Deref`
 --> E0220.rs:5:28
  |
5 | fn foo<T>() where T: Deref<Output = u32> {}
  |                            ^^^^^^ associated type `Output` not found

After:

error[E0220]: associated type `Output` not found for `Deref`
 --> E0220.rs:5:28
  |
5 | fn foo<T>() where T: Deref<Output = u32> {}
  |                            ^^^^^^ help: `Deref` has the following associated type: `Target`

@rustbot label +A-diagnostics +D-papercut

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rustbot commented Sep 8, 2023

r? @compiler-errors

(rustbot has picked a reviewer for you, use r? to override)

@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. A-diagnostics Area: Messages for errors, warnings, and lints D-papercut Diagnostics: An error or lint that needs small tweaks. labels Sep 8, 2023
@ShE3py ShE3py changed the title Improve "associated type not defined" diagnostics Improve "associated type not found" diagnostics Sep 8, 2023
compiler-errors
compiler-errors requested changes Sep 8, 2023
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tests/ui/associated-type-bounds/missing-trait-bound-for-assoc-fails.stderr Outdated
| ^^^^ associated type `Item` not found
| ^^^^
|
= help: `M` has no associated type, try removing `Item`
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This suggestion doesn't make sense imo.

tests/ui/associated-types/associated-types-path-1.stderr Outdated Show resolved Hide resolved
tests/ui/associated-consts/assoc-const-eq-missing.stderr Outdated Show resolved Hide resolved
compiler-errors
compiler-errors reviewed Sep 8, 2023
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compiler/rustc_hir_analysis/src/astconv/errors.rs Outdated
return err.emit();
}

let msg = if all_candidate_names.len() > 1 {
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I don't think we should suggest anything if there's >1 candidate.

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trait Qux {
    type A;
    type B;
}

fn quux<T>() where T: Qux<A = u32, ZZ = u32> {}

gives

error[E0220]: associated type `ZZ` not found for `Qux`
  --> E0220.rs:14:36
   |
14 | fn quux<T>() where T: Qux<A = u32, ZZ = u32> {}
   |                                    ^^
   |
help: `Qux` has the following associated types
   |
14 | fn quux<T>() where T: Qux<A = u32, A = u32> {}
   |                                    ~
14 | fn quux<T>() where T: Qux<A = u32, B = u32> {}
   |                                    ~

I think this is still helpful?

compiler/rustc_hir_analysis/src/astconv/errors.rs Outdated Show resolved Hide resolved
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@bors r+

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bors commented Sep 8, 2023

📌 Commit a0e0a32 has been approved by compiler-errors

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 Sep 8, 2023
@matthiaskrgr matthiaskrgr mentioned this pull request Sep 8, 2023
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bors added a commit to rust-lang-ci/rust that referenced this pull request Sep 8, 2023
@bors
Auto merge of rust-lang#115685 - matthiaskrgr:rollup-t31gowy, r=matth…
b0b8c52 
…iaskrgr

Rollup of 5 pull requests

Successful merges:

 - rust-lang#113807 (Tests crash from inappropriate use of common linkage)
 - rust-lang#115358 (debuginfo: add compiler option to allow compressed debuginfo sections)
 - rust-lang#115630 (Dont suggest use between `use` and cfg attr)
 - rust-lang#115662 (Improve "associated type not found" diagnostics)
 - rust-lang#115673 (Fix sanitize/cfg.rs test)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 69044a1 into rust-lang:master Sep 9, 2023
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bors commented Sep 9, 2023

⌛ Testing commit a0e0a32 with merge b0b8c52...

@rustbot rustbot added this to the 1.74.0 milestone Sep 9, 2023
rust-timer added a commit to rust-lang-ci/rust that referenced this pull request Sep 9, 2023
@rust-timer
Unrolled build for rust-lang#115662
f156a05 
Rollup merge of rust-lang#115662 - ShE3py:E0220-note, r=compiler-errors

Improve "associated type not found" diagnostics

```rs
use core::ops::Deref;

fn foo<T>() where T: Deref<Output = u32> {}
```

Before:
```
error[E0220]: associated type `Output` not found for `Deref`
 --> E0220.rs:5:28
  |
5 | fn foo<T>() where T: Deref<Output = u32> {}
  |                            ^^^^^^ associated type `Output` not found
```

After:
```
error[E0220]: associated type `Output` not found for `Deref`
 --> E0220.rs:5:28
  |
5 | fn foo<T>() where T: Deref<Output = u32> {}
  |                            ^^^^^^ help: `Deref` has the following associated type: `Target`
```

---

`@rustbot` label +A-diagnostics +D-papercut
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A-diagnostics Area: Messages for errors, warnings, and lints D-papercut Diagnostics: An error or lint that needs small tweaks. 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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