feat: add template-anchor-has-content

[johanrd]

Note

This is part of a series where Claude has audited eslint-plugin-ember against jsx-a11y, vuejs-accessibility, angular-eslint, lit-a11y and html-validate, ember-template-lint, and the HTML and WCAG specs.

Every <a href> rendered to the DOM is exposed as a link to assistive tech. Per ACCNAME 1.2 §4.3.2, the accessible name is computed from: aria-labelledby → aria-label → descendant text content → title. An anchor with none of these has no accessible name; a screen reader announces "link" with nothing else. Authoring basis: WCAG 2.1 SC 2.4.4 Link Purpose.

Adds template-anchor-has-content: flags <a href> with no text, no accessible-name attribute (aria-label / aria-labelledby / title), and no child that contributes an accessible name. Dynamic cases (mustache-only content) stay accepted — we can't know at lint time whether they resolve to a non-empty name.

aria-hidden treatment

The question "what does <span aria-hidden> (bare), aria-hidden="" (empty), or aria-hidden={{false}} mean?" has no single authoritative answer. We lean toward fewer false positives: treat a child with valueless / empty aria-hidden as NOT hidden — if someone writes <a href="/x"><span aria-hidden>X</span></a>, the child's content likely still contributes a name, so we don't flag the anchor. Only explicit aria-hidden="true" / {{true}} hides the child subtree from the name computation.

Flags

<a href="/x" />
<a href="/x"><span aria-hidden="true">X</span></a>
<a href="/x"><img aria-hidden="true" alt="Nope" /></a>
<a href="/x"><img /></a>
<a href="/x" aria-label="" />
<a href="/x">   </a>

Allows

<a href="/x">link text</a>
<a href="/x"><span aria-hidden>X</span></a>        {{! valueless — child content counts }}
<a href="/x"><img aria-hidden alt="Nope" /></a>    {{! same }}
<a href="/x" aria-label="Close" />
<a href="/x">{{@label}}</a>
<a href="/x"><img alt="Search" /></a>
<Link href="/x" />

Prior art

Plugin	Rule	Behavior
jsx-a11y	anchor-has-content	Flags <a> without text content or a recognized accessible-name attribute.
vuejs-accessibility	anchor-has-content	Flags <a> lacking content and aria-label; configurable accessibleChildren / accessibleDirectives.
lit-a11y	—	No anchor-has-content equivalent (anchor-is-valid covers href validity, not accessible-name content).
@angular-eslint/template	—	No equivalent rule.