fix(template-no-redundant-role): valueless <select size> stays combobox (Copilot review)

Per HTML boolean-attr semantics, a missing-value attribute's value is the
empty string — Number('') is 0; 0 is not > 1, so the implicit role of a
<select size> (no value) stays combobox. Previously we bailed out to
'unknown' for any sizeAttr.value that wasn't a GlimmerTextNode, conflating
valueless with dynamic. Split the two: valueless → combobox (static),
dynamic (mustache / concat) → unknown (skip).

Add an invalid test: <select role='combobox' size> flags as redundant
combobox.

Author: johanrd

lib/rules/template-no-redundant-role.js

@@ -61,9 +61,16 @@ function getSelectImplicitRole(node) {
   }
   const sizeAttr = attrs.find((a) => a.name === 'size');
   if (sizeAttr) {
-    if (!sizeAttr.value || sizeAttr.value.type !== 'GlimmerTextNode') {
-      // Dynamic `size` — can't tell whether implicit role is combobox or
-      // listbox, so bail out instead of risking a false positive.
+    // Valueless `size` (e.g. `<select size>`) — per HTML boolean-attr
+    // semantics the attribute value is an empty string, which Number()
+    // parses as 0. Per HTML's default size (>1 → listbox), 0 leaves the
+    // implicit role as combobox. Treat the same as the static-0 case.
+    if (!sizeAttr.value) {
+      return 'combobox';
+    }
+    if (sizeAttr.value.type !== 'GlimmerTextNode') {
+      // Dynamic `size={{...}}` / concat — can't tell whether the runtime
+      // value is >1 or not, so bail out instead of risking a false positive.
       return 'unknown';
     }
     const sizeValue = Number(sizeAttr.value.chars);

tests/lib/rules/template-no-redundant-role.js

@@ -87,6 +87,19 @@ ruleTester.run('template-no-redundant-role', rule, {
         },
       ],
     },
+    {
+      // Valueless `<select size>` — per HTML boolean-attr semantics, the
+      // attribute value is an empty string; Number('') is 0; 0 is NOT > 1,
+      // so the implicit role stays combobox. `role="combobox"` is therefore
+      // redundant and must be flagged.
+      code: '<template><select role="combobox" size></select></template>',
+      output: '<template><select size></select></template>',
+      errors: [
+        {
+          message: 'Use of redundant or invalid role: combobox on <select> detected.',
+        },
+      ],
+    },
     {
       // Role-fallback: unknown leading token is skipped per ARIA §4.1.
       // `role="xxyxyz button"` resolves to `button`, which IS redundant on