Masafumi Koba

Oh, I forgot that the rule depends on the [`css-functions-list`](https://github.com/niksy/css-functions-list) package rather than our internal utils. 😅 https://github.com/stylelint/stylelint/blob/baf7c0e4448e6e1b1d472b53df8a3dd35291449a/lib/rules/function-no-unknown/index.mjs#L19 Can you open an issue or pull request to the `css-functions-list` repo...

I think `css-functions-list` scrapes MDN, so it may be better to wait for publising the `calc-size()` page: https://github.com/niksy/css-functions-list/blob/25b4fb4a50edd41041ff0194390a18d659f590e4/generate-list.js#L67

@azat-io Thank you for creating the PR to `css-functions-list` too. It was merged, and the new version was released quickly! So, I think this PR is no longer necessary. As...

> i.e. _Fix `function-calc-no-unspaced-operator` false negatives for `calc-size`_ Sounds good. 👍🏼 @azat-io If you're interested, can you please add or update test cases about `calc-size`? There should be some rules...

Personally, I'm curious about the fork background or context. Can you show it here if possible?

@nzakas Do you provide some resources for your decision to fork it if any, such as documents, issues, etc.? I do want to know the background and CSSTree author's thoughts...

@nzakas Thank you for providing the discussion and context. I now understand the ESLint team's decision. Indeed, there is a maintenance issue in CSSTree, and I think we worry about...

@romainmenke @nzakas Thank you so much for the comment. I now understand the context better than before. 👍🏼 I understand CSSTree maintainers' thoughts, but simultaneously, the ESLint team's decision also...

Sorry for the late response. I'm looking at this 👀

@Mouvedia Do you have any concerns still? If no, we can merge.