fix(template-no-aria-label-misuse): specificity tiers, pre-indexed elementRoles, valueless-label, fixable meta (Copilot review)

- scoreMatch now uses three tiers: exact value (3) > set (2) > undefined (1).
  Previously set and undefined both added +1, so a stricter 'set' constraint
  could lose to a looser 'undefined' when both matched. Exact-value entries
  still win over 'set' (e.g. <img alt=''> → presentation still beats the
  generic alt-set entry).
- Pre-index elementRoles by tag name at module load (same pattern as PR #52's
  template-no-unsupported-role-attributes). Turns a ~80-key scan per call
  into a 1–5-key lookup.
- hasNonEmptyLabelAttr returns false when attr.value == null — a valueless
  aria-label / aria-labelledby carries no accessible name, so it shouldn't
  be treated as a non-empty (author-declared) label.
- Add meta.fixable: null — rule is not autofixable, be explicit.

Author: johanrd

lib/rules/template-no-aria-label-misuse.js

@@ -29,18 +29,24 @@ function scoreMatch(entry, node) {
     const isPresent = Boolean(nodeAttr);
     const staticValue = getStaticAttrString(node, spec.name);
 
+    // Specificity tiers: exact value match is strictest (3), "set" presence
+    // is stricter than "undefined" absence (2 vs 1). Previously `set` and
+    // `undefined` both scored 1, so a constraints-match on either tied; the
+    // tier split ensures a more specific "set" entry beats a looser
+    // "undefined" entry when both match — and an exact-value entry (e.g.
+    // <img alt=""> → presentation) still beats a plain "set" entry.
     if (spec.value !== undefined) {
       if (staticValue === null || staticValue.toLowerCase() !== spec.value) {
         return null;
       }
-      score += 2;
+      score += 3;
       continue;
     }
     if (spec.constraints?.includes('set')) {
       if (!isPresent) {
         return null;
       }
-      score += 1;
+      score += 2;
       continue;
     }
     if (spec.constraints?.includes('undefined')) {
@@ -55,20 +61,38 @@ function scoreMatch(entry, node) {
   return score;
 }
 
+// Pre-index elementRoles by tag name at module load. aria-query's Map is
+// static data; bucketing by tag turns the per-call scan (~80 keys) into a
+// 1–5 key lookup per tag. Mirrors the optimization landed on PR #52's
+// template-no-unsupported-role-attributes rule.
+const ELEMENT_ROLES_KEYS_BY_TAG = buildElementRolesIndex();
+
+function buildElementRolesIndex() {
+  const index = new Map();
+  for (const key of elementRoles.keys()) {
+    if (!index.has(key.name)) {
+      index.set(key.name, []);
+    }
+    index.get(key.name).push(key);
+  }
+  return index;
+}
+
 function getImplicitRole(node) {
+  const keys = ELEMENT_ROLES_KEYS_BY_TAG.get(node.tag);
+  if (!keys) {
+    return null;
+  }
   let best = null;
   let bestScore = -1;
-  for (const [key, roleList] of elementRoles.entries()) {
-    if (key.name !== node.tag) {
-      continue;
-    }
+  for (const key of keys) {
     const score = scoreMatch(key, node);
     if (score === null) {
       continue;
     }
     if (score > bestScore) {
       bestScore = score;
-      best = roleList[0];
+      best = elementRoles.get(key)[0];
     }
   }
   return best;
@@ -106,8 +130,11 @@ function hasNonEmptyLabelAttr(node, name) {
   if (!attr) {
     return false;
   }
-  if (!attr.value) {
-    return true;
+  // A valueless attribute (e.g. `<div aria-label>`) carries no accessible
+  // name. Treat it as empty — not as non-empty — so downstream checks don't
+  // mistake it for an author-declared label.
+  if (attr.value == null) {
+    return false;
   }
   if (attr.value.type === 'GlimmerTextNode') {
     return attr.value.chars !== '';
@@ -145,6 +172,7 @@ module.exports = {
       url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/template-no-aria-label-misuse.md',
       templateMode: 'both',
     },
+    fixable: null,
     schema: [
       {
         type: 'object',