Make `derive(Trait)` suggestion more accurate #119362

estebank · 2023-12-27T21:15:57Z

Only suggest derive(PartialEq) when both LHS and RHS types are the same, otherwise the suggestion is not useful.

rustbot · 2023-12-27T21:16:05Z

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fmease · 2023-12-27T21:26:01Z

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -2322,7 +2323,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
            .iter()
            .map(|e| (e.obligation.predicate, None, Some(e.obligation.cause.clone())))
            .collect();
-        self.suggest_derive(err, &preds);
+        self.suggest_derive(err, &preds, suggest_derive);
    }

    pub fn suggest_derive(


I find it confusing that this method is called suggest_derive but apparently does more than suggesting #[derive]. It also adds the note the trait[…] […] must be implemented. Adding the flag suggest_derive to … suggest_derive makes it even more confusing. Could this method be renamed or even refactored into two methods potentially allowing us to get rid of the bool parameter altogether?

I wanted to make this as minimal a diff as possible :)

suggest_derive also emits some extra notes (that I didn't want to lose). I'm assuming we added that after the method was created and we didn't modify the method name then. I can either rename the method and keep the argument, or split the logic in two (or three?) methods and call them only when needed.

I see :) If you can find a good name for it, go for a rename. You can also do a refactor instead either in this PR or or in a follow-up one, larger diffs are fine by me.

What do you think of the change?

Thanks, it's an improvement. Although, the way it's split into two methods doesn't feel right: note_predicate_source_and_get_derives still does two things, it calculates traits and derives and only adds a note for traits but never for derive and we do a bunch of work formatting derives just to throw it away if !suggest_derive.

fmease

r=me with the actionable subset of my most recent suggestions applied or if you find a better way to split those two functions then go for it and re-request a review :)

compiler/rustc_hir_typeck/src/method/suggest.rs

fmease · 2023-12-29T11:38:27Z

compiler/rustc_hir_typeck/src/method/suggest.rs

        &self,
        err: &mut Diagnostic,
        unsatisfied_predicates: &[(
            ty::Predicate<'tcx>,
            Option<ty::Predicate<'tcx>>,
            Option<ObligationCause<'tcx>>,
        )],
-    ) {
+    ) -> Vec<(String, Span, String)> {


Hmm, it's only in the error path but I'd love to skip the entire if let Some(diagnostic_name) = self.tcx.get_diagnostic_name(trait_pred.def_id()) check if !suggest_derive but then we'd need to introduce suggested_derive: bool to note_pre_src_and_get_derives :(

compiler/rustc_hir_typeck/src/method/suggest.rs

Only suggest `derive(PartialEq)` when both LHS and RHS types are the same, otherwise the suggestion is not useful.

estebank · 2024-01-04T00:40:10Z

@bors r=fmease

bors · 2024-01-04T00:40:13Z

📌 Commit 2474b37 has been approved by fmease

It is now in the queue for this repository.

…n, r=fmease Make `derive(Trait)` suggestion more accurate Only suggest `derive(PartialEq)` when both LHS and RHS types are the same, otherwise the suggestion is not useful.

…mpiler-errors Rollup of 10 pull requests Successful merges: - rust-lang#118521 (Enable address sanitizer for MSVC targets using INFERASANLIBS linker flag) - rust-lang#119026 (std::net::bind using -1 for openbsd which in turn sets it to somaxconn.) - rust-lang#119195 (Make named_asm_labels lint not trigger on unicode and trigger on format args) - rust-lang#119204 (macro_rules: Less hacky heuristic for using `tt` metavariable spans) - rust-lang#119362 (Make `derive(Trait)` suggestion more accurate) - rust-lang#119397 (Recover parentheses in range patterns) - rust-lang#119414 (bootstrap: Move -Clto= setting from Rustc::run to rustc_cargo) - rust-lang#119417 (Uplift some miscellaneous coroutine-specific machinery into `check_closure`) - rust-lang#119540 (Don't synthesize host effect args inside trait object types) - rust-lang#119555 (Add codegen test for RVO on MaybeUninit) r? `@ghost` `@rustbot` modify labels: rollup

…iaskrgr Rollup of 10 pull requests Successful merges: - rust-lang#118521 (Enable address sanitizer for MSVC targets using INFERASANLIBS linker flag) - rust-lang#119026 (std::net::bind using -1 for openbsd which in turn sets it to somaxconn.) - rust-lang#119195 (Make named_asm_labels lint not trigger on unicode and trigger on format args) - rust-lang#119204 (macro_rules: Less hacky heuristic for using `tt` metavariable spans) - rust-lang#119362 (Make `derive(Trait)` suggestion more accurate) - rust-lang#119397 (Recover parentheses in range patterns) - rust-lang#119417 (Uplift some miscellaneous coroutine-specific machinery into `check_closure`) - rust-lang#119539 (Fix typos) - rust-lang#119540 (Don't synthesize host effect args inside trait object types) - rust-lang#119555 (Add codegen test for RVO on MaybeUninit) r? `@ghost` `@rustbot` modify labels: rollup

compiler-errors · 2024-01-04T22:25:23Z

@bors rollup

Rollup merge of rust-lang#119362 - estebank:restrict-derive-suggestion, r=fmease Make `derive(Trait)` suggestion more accurate Only suggest `derive(PartialEq)` when both LHS and RHS types are the same, otherwise the suggestion is not useful.

rustbot assigned wesleywiser Dec 27, 2023

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 Dec 27, 2023

estebank mentioned this pull request Dec 27, 2023

Emit better suggestions for &T == T and T == &T #118431

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fmease reviewed Dec 27, 2023

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fmease assigned fmease and unassigned wesleywiser Dec 28, 2023

fmease added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 28, 2023

estebank force-pushed the restrict-derive-suggestion branch from 105e206 to c9b0707 Compare December 28, 2023 20:26

estebank added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Dec 28, 2023

fmease approved these changes Dec 29, 2023

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fmease added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 29, 2023

estebank added 2 commits January 3, 2024 23:49

Make derive(Trait) suggestion more accurate

7f795a5

Only suggest `derive(PartialEq)` when both LHS and RHS types are the same, otherwise the suggestion is not useful.

review comments

2474b37

estebank force-pushed the restrict-derive-suggestion branch from c9b0707 to 2474b37 Compare January 4, 2024 00:12

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 4, 2024

compiler-errors mentioned this pull request Jan 4, 2024

Rollup of 10 pull requests #119565

Closed

matthiaskrgr mentioned this pull request Jan 4, 2024

Rollup of 10 pull requests #119569

Merged

bors merged commit 6526b16 into rust-lang:master Jan 4, 2024
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rustbot added this to the 1.77.0 milestone Jan 4, 2024

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Make `derive(Trait)` suggestion more accurate #119362

Make `derive(Trait)` suggestion more accurate #119362

estebank commented Dec 27, 2023

rustbot commented Dec 27, 2023

fmease Dec 27, 2023

estebank Dec 28, 2023 •

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fmease Dec 28, 2023 •

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estebank commented Jan 4, 2024

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compiler-errors commented Jan 4, 2024

Make derive(Trait) suggestion more accurate #119362

Make derive(Trait) suggestion more accurate #119362

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estebank commented Dec 27, 2023

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estebank commented Jan 4, 2024

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compiler-errors commented Jan 4, 2024

Make `derive(Trait)` suggestion more accurate #119362

Make `derive(Trait)` suggestion more accurate #119362

estebank Dec 28, 2023 •

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fmease Dec 28, 2023 •

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fmease Dec 29, 2023 •

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