aria-allowed-role
Explicit role must be permitted for its host element
Checks that an explicit role="" attribute is one of the roles the ARIA-in-HTML specification permits for the host element (e.g. role="tab" is not permitted on <nav>).
Applies to. Applies to elements with an explicit, valid, non-abstract role, where the host element/attribute combination has an asserted permitted-roles constraint in the ARIA-in-HTML table (src/core/aria-helpers.js ALLOWED_ROLES_BY_ELEMENT).
Expectation. The explicit role is one of the roles the ARIA-in-HTML specification permits for that host element. Reported at CANTTELL rather than FAIL: ARIA-in-HTML's permitted-roles table is an author conformance requirement with no ACT rule and no WCAG mapping in any source. The role the author asked for is still the role assistive technology exposes, so whether the combination harms anyone depends on the widget, not on the table.
Examples
<nav role="navigation">...</nav>
`role="navigation"` is permitted on `<nav>` by the ARIA-in-HTML spec (it's also the element's implicit role).
<nav role="tab">...</nav>
`role="tab"` is not one of the roles ARIA-in-HTML permits on `<nav>`.