Suggest using type args directly instead of equality constraint #122591

gurry · 2024-03-16T12:02:03Z

When type arguments are written erroneously using an equality constraint we suggest specifying them directly without the equality constraint.

Fixes #122162

Changes the diagnostic in the issue from:

error[E0229]: associated type bindings are not allowed here
9 | impl std::cmp::PartialEq<Rhs = T> for S {
  |                          ^^^^^^^ associated type not allowed here
  |

to

error[E0229]: associated type bindings are not allowed here
9 | impl std::cmp::PartialEq<Rhs = T> for S {
  |                          ^^^^^^^ associated type not allowed here
  |
help: to use `T` as a generic argument specify it directly
  |
  |      impl std::cmp::PartialEq<T> for S {
  |                               ~

rustbot · 2024-03-16T12:02:11Z

r? @lcnr

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tests/ui/associated-type-bounds/issue-102335-ty.stderr

compiler/rustc_hir_analysis/src/astconv/errors.rs

bors · 2024-03-21T09:00:30Z

☔ The latest upstream changes (presumably #121123) made this pull request unmergeable. Please resolve the merge conflicts.

gurry · 2024-03-22T02:07:27Z

@rustbot label -S-waiting-on-review +S-waiting-on-author

lcnr · 2024-03-22T11:01:13Z

r? @fmease

bors · 2024-03-22T13:14:38Z

☔ The latest upstream changes (presumably #120926) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot · 2024-03-22T14:20:15Z

HIR ty lowering was modified

cc @fmease

gurry · 2024-03-23T07:35:38Z

@rustbot label +S-waiting-on-review -S-waiting-on-author

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

tests/rustdoc-ui/invalid_associated_const.stderr

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

tests/ui/associated-types/associated-types-eq-2.stderr

gurry · 2024-04-01T05:05:37Z

@fmease I have updated the code as per your review comments. The main thing to note is that I have changed the approach such that we make the "use directly" suggestion only there is a type param with a matching name. If not, we suggest removal.
@rustbot label -S-waiting-on-author +S-waiting-on-review

gurry · 2024-04-03T12:02:41Z

☔ The latest upstream changes (presumably #123396) made this pull request unmergeable. Please resolve the merge conflicts.

Rebased

fmease

Sorry for taking so long again! I should have more time for review now.
I have a couple of suggestions.

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

tests/ui/associated-consts/issue-102335-const.stderr

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

tests/ui/associated-types/associated-types-eq-2.rs

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

fmease · 2024-04-12T15:13:42Z

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

+
+        // Check if the type has a generic param with the
+        // same name as the assoc type name in type binding
+        let generics = tcx.generics_of(def_id);


generics_of can panic if the definition (identified by the def_id) can't have generic parameters. Could you check if we can indeed panic here, e.g. if the definition is a type parameter:

fn f<T>() { let _: T<X = ()>; }

If it does, we need to add some checks before trying to use generics_of.

No, this does not ICE

fmease · 2024-04-12T15:15:46Z

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

+        && let hir::TypeBindingKind::Equality { term } = binding.kind
+    {
+        // Suggests removal of the offending binding
+        let suggest_removal = |e: &mut Diag<'_>| {


Note to self: I still need to review this function. I suspect it can be simplified by a lot but let's see.

gurry · 2024-04-13T06:14:45Z

Sorry for taking so long again! I should have more time for review now. I have a couple of suggestions.

No worries @fmease.

I'll incorporate your suggestions.

gurry · 2024-04-19T01:37:26Z

@fmease please review

gurry · 2024-04-21T03:14:20Z

@rustbot label -S-waiting-on-author +S-waiting-on-review

fmease · 2024-04-21T14:36:07Z

I've left some comments here (linking this from here for visibility).

gurry · 2024-04-22T05:55:55Z

I've left some comments here (linking this from here for visibility).

Thanks for all the suggestions. They have made the PR so much better.

If you're okay, we can merge this PR and take up the problems around macros in a later PR.

@rustbot label -S-waiting-on-author +S-waiting-on-review

fmease · 2024-04-23T10:42:41Z

If you're okay, we can merge this PR and take up the problems around macros in a later PR.

👍

@bors r+ rollup

bors · 2024-04-23T10:42:43Z

📌 Commit f7ebad4 has been approved by fmease

It is now in the queue for this repository.

Rollup of 7 pull requests Successful merges: - rust-lang#120929 (Wrap dyn type with parentheses in suggestion) - rust-lang#122591 (Suggest using type args directly instead of equality constraint) - rust-lang#122598 (deref patterns: lower deref patterns to MIR) - rust-lang#123048 (alloc::Layout: explicitly document size invariant on the type level) - rust-lang#123993 (Do `check_coroutine_obligations` once per typeck root) - rust-lang#124218 (Allow nesting subdiagnostics in #[derive(Subdiagnostic)]) - rust-lang#124285 (Mark ``@RUSTC_BUILTIN`` search path usage as unstable) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#122591 - gurry:122162-impl-type-binding-suggestion, r=fmease Suggest using type args directly instead of equality constraint When type arguments are written erroneously using an equality constraint we suggest specifying them directly without the equality constraint. Fixes rust-lang#122162 Changes the diagnostic in the issue from: ```rust error[E0229]: associated type bindings are not allowed here 9 | impl std::cmp::PartialEq<Rhs = T> for S { | ^^^^^^^ associated type not allowed here | ``` to ```rust error[E0229]: associated type bindings are not allowed here 9 | impl std::cmp::PartialEq<Rhs = T> for S { | ^^^^^^^ associated type not allowed here | help: to use `T` as a generic argument specify it directly | | impl std::cmp::PartialEq<T> for S { | ~ ```

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Emit suggestions when equality constraints are wrongly used

f7ebad4

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Rollup of 7 pull requests #124295

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Suggest using type args directly instead of equality constraint #122591

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Suggest using type args directly instead of equality constraint #122591

Suggest using type args directly instead of equality constraint #122591

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