New lint: empty_enum_variants_with_brackets

[ARandomDev99]

This lint checks for enum variants that don't have any fields but are declared using brackets.

Closes #12007

changelog: new lint: [empty_enum_variants_with_brackets]

[rustbot]

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[J-ZhengLi]

Hello~ 😄

Since this code logic shares a lot common with [empty_struct_with_brackets], for example those functions are exactly the same, I think you can merge these two files together, but keep them as separated lints.

That means have the declare_lint_pass! change to something like... :

declare_lint_pass!(EmptyWithBrackets => [
    EMPTY_ENUM_VARIANTS_WITH_BRACKETS,
    EMPTY_STRUCTS_WITH_BRACKETS,
]);

and in that EarlyLintPass impl, move your lint logic there:

impl EarlyLintPass for EmptyWithBrackes {
    /// code for empty_structs_with_brackets... bla bla
    fn check_item()

   /// your logic...
    fn check_variant()
}

reduces repeating code

[ARandomDev99]

That makes sense. I shall make these changes.

[rustbot]

There are merge commits (commits with multiple parents) in your changes. We have a no merge policy so these commits will need to be removed for this pull request to be merged.

You can start a rebase with the following commands:

$ # rebase
$ git rebase -i master
$ # delete any merge commits in the editor that appears
$ git push --force-with-lease

The following commits are merge commits:

• 4191258

[ARandomDev99]

I'll be opening another PR after making the suggested changes.

[bors]

☔ The latest upstream changes (presumably #10283) made this pull request unmergeable. Please resolve the merge conflicts.

[llogiq]

Feel free to add r? @llogiq to the description so I get to review it, as I already have the relevant context.

[ARandomDev99]

@llogiq another PR I've opened regarding this issue has already been merged. :)