Apparent discrepancy in the definition of a block between rules

Environment

Node version: 16.14.1 npm version: 8.5.0 Local ESLint version: 7.32.0 Global ESLint version: N/A Operating System: OS X

What parser are you using?

@babel/eslint-parser

What did you do?

For the lines-around-comment rule, setting allowBlockStart: true is not respected for switch statements.

According to this issue: https://github.com/eslint/eslint/issues/9653, that is because switch statement curly braces are not considered “blocks”. See comment: https://github.com/eslint/eslint/issues/9653#issuecomment-347386313

However, the padded-blocks rule appears to interpret switch statement curly braces as blocks which results in a discrepancy that can only be remedied by never including a comment inside a switch statement’s opening curly brace.

Relevant rule configurations:

'lines-around-comment': [
    2,
    {
        allowArrayStart: true,
        allowBlockStart: true,
        allowObjectStart: true,
        beforeBlockComment: true,
        beforeLineComment: true,
    },
],
'padded-blocks': ['error', 'never'],

Sample code

let someValue = "a";

switch (someValue) {
    // some comment
  case 'a':
    someValue = "b";
    break;
  
  default:
    someValue = "c";
}

Link to reproduction of issue: https://eslint.org/play/#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

What did you expect to happen?

I expected that setting allowBlockStart: true would preclude a violation of beforeLineComment: true in the lines-around-comment rule.

Given the discussion in issue 9653, I would then expect 'padded-blocks': ['error', 'never'] to not result in an error inside a switch statement’s opening curly brace.

What actually happened?

To visualize, visit the reproduction and add a line break before the comment. Note that the lines-around-comment error becomes a padded-blocks error because the two rules do not consistently interpret switch case curly braces as blocks.

https://eslint.org/play/#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

Participation

• I am willing to submit a pull request for this issue.

Additional comments

No response

[snitin315]

@kboucher the next release is scheduled on 29th July.

[snitin315]

I’ll prepare a fix for it.