Don't suggest doc(hidden) or unstable variants in wildcard lint #7407

m-ou-se · 2021-06-26T13:26:10Z

Clippy's wildcard lint would suggest doc(hidden) and unstable variants for non_exhaustive enums, even though those aren't part of the public interface (yet) and should only be matched on using a _, just like potential future additions to the enum. There was already some logic to exclude a single doc(hidden) variant. This extends that to all hidden variants, and also hides #[unstable] variants.

See rust-lang/rust#85746 (comment)

This PR includes #7406 as the first commit.

Here's the diff that this PR adds on top of that PR: m-ou-se/fork@std-errorkind...m-ou-se:doc-hidden-variants

Please write a short comment explaining your change (or "none" for internal only changes)

changelog: No longer suggest unstable and doc(hidden) variants in wildcard lint. wildcard_enum_match_arm, match_wildcard_for_single_variants

Every time we add something to this enum in std, this test breaks.

rust-highfive · 2021-06-26T13:26:13Z

r? @phansch

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xFrednet

Could you update the changelog message to mention the specific lints that are effected by this change? That makes writing the change log easier in the end. In this case, it should be the lint wildcard_enum_match_arm

The rest looks good to me.

Hey @flip1995, I would take over the review of this PR if that works for you :)

xFrednet · 2021-06-28T19:25:09Z

clippy_lints/src/matches.rs

@@ -1033,7 +1033,7 @@ fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>])

    // Accumulate the variants which should be put in place of the wildcard because they're not
    // already covered.
-    let mut missing_variants: Vec<_> = adt_def.variants.iter().collect();
+    let mut missing_variants: Vec<_> = adt_def.variants.iter().filter(|x| !is_hidden(cx, x)).collect();


I think here it would be good to differentiate between the enums origin. It would make sense to me to also cover hidden/unstable variations if they originate from the same crate. (I couldn't find a check for that in the current implementation)

I'm also debating if that should be configurable, but I believe there is no real reason for that.

I don't think this has to be done in this PR. I like this idea though. Can you open a good-first-issue issue for this, please?

clippy_lints/src/matches.rs

flip1995 · 2021-06-29T08:58:01Z

(Un-assigning from phansch, since he's taking a break, thanks for taking over the review @xFrednet!)

xFrednet · 2021-06-30T08:06:44Z

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

This fixes a bug where match_wildcard_for_single_variants produced a bad suggestion where besides the missing variant, one or more hidden variants were left. This also adds tests to the ui-tests match_wildcard_for_single_variants and wildcard_enum_match_arm to make sure that the correct suggestion is produced.

flip1995 · 2021-07-01T10:49:40Z

@xFrednet can you review my changes, please? If any changes should be required I'll do them in a follow-up PR, I want to get this merged, so I can sync Clippy to Rust.

@bors r+

Don't suggest doc(hidden) or unstable variants in wildcard lint Clippy's wildcard lint would suggest doc(hidden) and unstable variants for non_exhaustive enums, even though those aren't part of the public interface (yet) and should only be matched on using a `_`, just like potential future additions to the enum. There was already some logic to exclude a *single* doc(hidden) variant. This extends that to all hidden variants, and also hides `#[unstable]` variants. See rust-lang/rust#85746 (comment) This PR includes #7406 as the first commit. Here's the diff that this PR adds on top of that PR: m-ou-se/fork@std-errorkind...m-ou-se:doc-hidden-variants --- *Please write a short comment explaining your change (or "none" for internal only changes)* changelog: - No longer suggest unstable and doc(hidden) variants in wildcard lint.

flip1995 · 2021-07-01T15:02:18Z

@bors retry

bors · 2021-07-01T15:02:25Z

⌛ Testing commit fae7a09 with merge 753bce3...

bors · 2021-07-01T15:16:54Z

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: flip1995
Pushing 753bce3 to master...

xFrednet

The rest looks good to me 👍

xFrednet · 2021-07-01T17:04:35Z

tests/ui/wildcard_enum_match_arm.stderr

+  --> $DIR/wildcard_enum_match_arm.rs:101:13
+   |
+LL |             _ => (),
+   |             ^ help: try this: `Enum::B | _`


I find it confusing that the lint suggests here to use the enum value in the same arm as the wildcard. That would mean that future additions would also run into this branch.

It would be good to either add a note to explain why a wildcard has to be present here or to make the suggestion to have two arms like this:

Enum::B => {}, _ => { /* Hidden values */ }

Adding a note that the enum includes hidden, or unstable values would still be good.

A X | _ pattern is already caught by another lint, so this shouldn't be an issue.

Don't use exact definition of std's ErrorKind in test.

3e59563

Every time we add something to this enum in std, this test breaks.

rust-highfive assigned phansch Jun 26, 2021

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties label Jun 26, 2021

Don't suggest unstable and doc(hidden) variants.

38569c0

m-ou-se force-pushed the doc-hidden-variants branch from 94470ff to 38569c0 Compare June 26, 2021 13:28

m-ou-se mentioned this pull request Jun 26, 2021

Redefine ErrorKind::Other and stop using it in std. rust-lang/rust#85746

Merged

xFrednet requested changes Jun 28, 2021

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flip1995 assigned flip1995 and unassigned phansch Jun 29, 2021

rustbot added S-waiting-on-author Status: This is awaiting some action from the author. (Use `@rustbot ready` to update this status) and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties labels Jun 30, 2021

flip1995 added 2 commits July 1, 2021 11:47

Simplify wildcard_enum_match_arm test

0ffba7a

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bors merged commit 753bce3 into rust-lang:master Jul 1, 2021

xFrednet mentioned this pull request Jul 1, 2021

Improve wildcard_enum_match_arm lints to take the enums origin into account #7419

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xFrednet reviewed Jul 1, 2021

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m-ou-se deleted the doc-hidden-variants branch July 2, 2021 18:31

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Don't suggest doc(hidden) or unstable variants in wildcard lint #7407

Don't suggest doc(hidden) or unstable variants in wildcard lint #7407

m-ou-se commented Jun 26, 2021 •

edited by flip1995

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Don't suggest doc(hidden) or unstable variants in wildcard lint #7407

Don't suggest doc(hidden) or unstable variants in wildcard lint #7407

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m-ou-se commented Jun 26, 2021 •

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