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ota-meshi / eslint-plugin-regexp

ESLint plugin for finding regex mistakes and style guide violations.

Home Page:https://ota-meshi.github.io/eslint-plugin-regexp/

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The order enforced by `sort-alternatives` depends on characters outside the sorted alternatives

RunDevelopment opened this issue · comments

commented

Description
Right now, alternatives are sorted 1) by the prefix returned by getLongestPrefix and 2) by raw source code. The bug is that getLongestPrefix will also possibly return one character after the alternatives, which means that the sort order of the alternatives depends not only on the alternatives but also on the characters after them. This has some surprising consequences. E.g. right now, sort-alternatives will sort as follows:

var foo = /^(?:a|ab)a/u;
var foo = /^(?:ab|a)c/u;

I would classify this as a bug.

Fixing this issue will be quite easy. The RAA version of getLongestPrefix in #415 has options that control its behavior. This includes an option to ensure that the prefix is only of the alternative and does not contain characters from after it.