New Rule: no-reference-like-url

[TKDev7]

Rule details

Warn when URLs are also defined identifiers.

What type of rule is this?

Warns about a potential problem

Example code

[Mercury](mercury) is the first planet from the sun.

[mercury]: https://example.com/mercury/

Prior Art

[remark-lint-no-reference-like-url](https://github.com/remarkjs/remark-lint/tree/main/packages/remark-lint-no-reference-like-url)

Participation

• I am willing to submit a pull request to implement this rule.

Additional comments

While full URLs for definition identifiers are okay ([https://example.com]: https://example.com), and what looks like an identifier could be an actual URL (text), the more common case is that, assuming a definition [alpha]: https://example.com, then a link text should instead have been [text][alpha].

[lumirlumir]

Thanks for opening an issue. I would like to confirm that my understanding is correct. Could you take a look?

If we write a Markdown document like below, it is recognized as a valid Link node and Definition node.

AST

[**Mercury**](mercury) is the first planet from the sun.

[mercury]: https://example.com/mercury/

However, since we use a Definition node [mercury]: https://example.com/mercury/ with the identifier mercury, this rule assumes that the user's original intention was to use a LinkReference node like [**Mercury**][mercury], not a Link node like [**Mercury**](mercury). So, it raises a warning because a Link node was incorrectly used instead of a LinkReference node.

[nzakas]

@lumirlumir just a reminder: when you start triaging and issue, please move it into the "Triaging" column in the Triage board.

[TKDev7]

@lumirlumir Yes exactly.

[lumirlumir]

@nzakas Thanks for pointing that out — I’ll keep it in mind.

---

@TKDev7 Thanks for your response.

I’d love to hear more thoughts from the @eslint/eslint-team, as I see both pros and cons to this.

Pros: There’s prior art remark-lint-no-reference-like-url, so adopting this rule could help users transition to ESLint — similar to how we've incorporated rules from Markdownlint and Remark-lint.

Cons: I’m not sure how broadly useful this rule would be. It seems to address only a few edge cases.

[Tanujkanti4441]

Reporting the use of reference labels in link syntax makes sense to me. If this is really an edge case, I would say we can create a rule that will report this case, and also, if the reference label is not used anywhere?

[lumirlumir]

if the reference label is not used anywhere?

@Tanujkanti4441 I’ve created a separate issue for it: #424 👍

[nzakas]

Makes sense to me. 👍