feat: no-useless-escape support v flag

[ota-meshi]

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What is the purpose of this pull request? (put an "X" next to an item)

[X] Changes an existing rule (template)

What changes did you make? (Give an overview)

Refs #17223

This PR modifies the no-useless-escape rule and adds support for regexp v flag.

Is there anything you'd like reviewers to focus on?

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[nzakas]

LGTM, thanks! Would like @mdjermanovic to review before merging.

[mdjermanovic]

When the useless escape is an operand of -- or &&, the "escapeBackslash" suggestion is wrong and therefore shouldn't be offered.

For example:

/* eslint no-useless-escape: "error" */

/[\p{ASCII}--\.]/v;

After applying "Replace the \ with \\ to include the actual backslash character":

/* eslint no-useless-escape: "error" */

/[\p{ASCII}--\\.]/v; // parsing error

validateRegExp could pass an additional boolean argument to function report to exclude this suggestion.

[ota-meshi]

Oh... Thank you for finding that issue. I didn't notice that.
Do you think it should be an auto-fix instead of a suggestion?

[mdjermanovic]

Do you think it should be an auto-fix instead of a suggestion?

No, it still could be some other kind of mistake in writing the pattern that just happened to manifest as a useless escape, so it seems better to report the problem and let the user choose whether to apply the suggestion to remove \ or fix the pattern in another way. I'd just remove the other, invalid suggestion (in this special case only).

[ota-meshi]

I got it! Thank you for letting me know your thoughts. I will fix that.

[ota-meshi]

I fixed that. Could you check it again?

[mdjermanovic]

LGTM, thanks!