What minimal example or steps are needed to reproduce the bug?

[data-cursor] {
	cursor: attr(data-cursor type(<custom-ident>), default);
}

[data-anchor] {
	anchor-name: attr(data-anchor type(<custom-ident>));
}

[data-landmark] {
	view-transition-name: attr(data-landmark type(<custom-ident>));
}

What minimal configuration is needed to reproduce the bug?

{
    "rules": {
        "declaration-property-value-no-unknown": true
    }
}

How did you run Stylelint?

Demo

Which Stylelint-related dependencies are you using?

{
	"stylelint": "16.24.0"
}

What did you expect to happen?

No problems to be reported.

What actually happened?

The following problems were reported:

example.css
2:10-57 error Cannot parse property value "attr(data-cursor type(<custom-ident>), default)" for property "cursor" (declaration-property-value-no-unknown)
6:15-53 error Cannot parse property value "attr(data-anchor type(<custom-ident>))" for property "anchor-name" (declaration-property-value-no-unknown)
10:24-64 error Cannot parse property value "attr(data-landmark type(<custom-ident>))" for property "view-transition-name" (declaration-property-value-no-unknown)

Additional Info

For content property, it only supports the fallback value and the unit, but does not support the type. For example:

::after {
	/* The following rules are valid. */
	content: attr(data-content, "fallback");
	content: attr(data-content raw-string);

	/* The following rules will report errors. */
	content: attr(data-content type(<string>));
	content: attr(data-content type(*));
}

Do you have a proposal to fix the bug?

Update syntax in CSSTree.

Sorry, I don't know how to extend the syntax myself using the languageOptions configuration property to support new syntax of attr() of every properties. Can you help me?