Improve diagnostics for functions in `struct` definitions #76808

LeSeulArtichaut · 2020-09-16T21:24:07Z

Tries to implement #76421.
This is probably going to need unit tests, but I wanted to hear from review all the cases tests should cover.

I'd like to follow up with the "mechanically applicable suggestion here that adds an impl block" step, but I'd need guidance. My idea for now would be to try to parse a function, and if that succeeds, create a dummy ast::Item impl block to then format it using pprust. Would that be a viable approach? Is there a better alternative?

r? @matklad cc @estebank

jyn514 · 2020-09-16T22:55:06Z

It would be helpful to add a UI test for the example in #76421 - even if it doesn't hit all the cases, it helps show that the diagnostic looks roughly right.

LeSeulArtichaut · 2020-09-17T16:45:13Z

@jyn514 I pushed the test

Dylan-DPC-zz · 2020-11-13T19:57:09Z

@matklad any updates?

compiler/rustc_parse/src/parser/item.rs

Dylan-DPC-zz · 2021-01-31T15:51:55Z

r? @estebank

bors · 2021-03-17T20:07:17Z

☔ The latest upstream changes (presumably #83188) made this pull request unmergeable. Please resolve the merge conflicts.

jackh726

@LeSeulArtichaut Do you want to just try to get the the current suggestion merged and then make a followup PR with an even better error? If so, then r=me on this, with or without an additional comment on the test.

In future PRs, I would like to see tests for unions or enums too. Or feel free to add that to this PR if it works.

compiler/rustc_parse/src/parser/item.rs

src/test/ui/structs/struct-fn-in-definition.rs

jackh726 · 2021-05-03T21:38:59Z

r? @jackh726

jackh726 · 2021-05-03T21:46:43Z

@bors delegate+

bors · 2021-05-03T21:46:45Z

✌️ @LeSeulArtichaut can now approve this pull request

jackh726 · 2021-05-07T20:58:29Z

@bors r+

bors · 2021-05-07T20:58:30Z

📌 Commit 6717f81 has been approved by jackh726

LeSeulArtichaut · 2021-05-07T20:59:23Z

@jackh726 Enums did not work, I added a new commit to this PR. I also added a better test description as you requested.

Do you want to just try to get the the current suggestion merged and then make a followup PR with an even better error?

What would an "even better error" look like? Do you mean a machine-applicable suggestion that extracts the function to an impl block, as estebank suggested? If so I'd prefer that to be in a follow-up PR.

PS: you're too fast

LeSeulArtichaut · 2021-05-07T21:01:56Z

compiler/rustc_parse/src/parser/item.rs


                let struct_def = if this.check(&token::OpenDelim(token::Brace)) {
                    // Parse a struct variant.
-                    let (fields, recovered) = this.parse_record_struct_body()?;
+                    let (fields, recovered) = this.parse_record_struct_body("struct")?;


Note that this can give some slightly ankward results:

enum Foo { Variant { fn bar() {} } }

error: functions are not allowed in struct definitions --> test.rs:5:9 | 5 | fn bar() {} | ^^^^^^^^^^^ | = help: unlike in C++, Java, and C#, functions are declared in `impl` blocks = help: see https://doc.rust-lang.org/book/ch05-03-method-syntax.html for more information

Doesn't seem very important to me however

Hmm, I see. If it comes up, a fairly easy fix might be to add a struct flag that is true in an actual struct and false in a enum variant.

jackh726 · 2021-05-07T21:40:53Z

What would an "even better error" look like? Do you mean a machine-applicable suggestion that extracts the function to an impl block, as estebank suggested? If so I'd prefer that to be in a follow-up PR.

Yeah, the machine-applicable suggestion.

PS: you're too fast

Only sometimes :)

Rollup of 6 pull requests Successful merges: - rust-lang#76808 (Improve diagnostics for functions in `struct` definitions) - rust-lang#84887 (Remove SpanInterner::get) - rust-lang#85034 (fix null pointer error messages) - rust-lang#85038 (Don't stop running rustdoc-gui tests at first failure) - rust-lang#85044 (Use `path.exists()` instead of `fs::metadata(path).is_ok()`) - rust-lang#85052 (rustdoc: Link to the docs on namespaces when an unknown disambiguator is found) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

rust-highfive assigned matklad Sep 16, 2020

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jyn514 added A-diagnostics Area: Messages for errors, warnings, and lints T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 16, 2020

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LeSeulArtichaut added 3 commits May 7, 2021 21:44

Improve diagnostics for functions in struct definitions

cecb3be

Add basic test

1e642f0

Also take unions and enums into account

6717f81

LeSeulArtichaut force-pushed the diagnose-functions-struct branch from 644975f to 6717f81 Compare May 7, 2021 20:50

LeSeulArtichaut 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 May 7, 2021

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Dylan-DPC-zz mentioned this pull request May 7, 2021

Rollup of 6 pull requests #85057

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bors merged commit eb36bc6 into rust-lang:master May 8, 2021

rustbot added this to the 1.54.0 milestone May 8, 2021

LeSeulArtichaut deleted the diagnose-functions-struct branch May 8, 2021 10:54

dtolnay mentioned this pull request May 12, 2021

Allow struct and enum to contain inner attrs #84414

Closed

LingMan mentioned this pull request May 29, 2021

ICE: panicked at 'explicit panic', compiler/rustc_errors/src/diagnostic_builder.rs:424:13 #85794

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Improve diagnostics for functions in `struct` definitions #76808

Improve diagnostics for functions in `struct` definitions #76808

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Improve diagnostics for functions in struct definitions #76808

Improve diagnostics for functions in struct definitions #76808

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LeSeulArtichaut commented Sep 16, 2020

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Improve diagnostics for functions in `struct` definitions #76808

Improve diagnostics for functions in `struct` definitions #76808

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