Fix accessible name calculation bug related to nested <label>s

.changeset/little-pets-shave.md

@@ -0,0 +1,5 @@
+---
+"@siteimprove/alfa-aria": patch
+---
+
+**Fixed:** A bug in the accessible name computation where nested labels would cause a crash or incorrect name has been fixed.

packages/alfa-aria/src/feature.ts

@@ -194,12 +194,12 @@ const nameFromLabel = (element: Element, device: Device, state: State) => {
       ),
     );
 
-  const names = references.collect((element) =>
+  const names = references.collect((label) =>
     Name.fromNode(
-      element,
+      label,
       device,
-      state.reference(element, element).recurse(true).descend(false),
-    ).map((name) => [name, element] as const),
+      state.reference(element, label).recurse(true).descend(false),
+    ).map((name) => [name, label] as const),
   );
 
   const name = names

packages/alfa-aria/src/name/state.ts

@@ -51,15 +51,17 @@ export class State implements Equatable, Serializable<State.JSON> {
 
   /**
    * The element that referenced the name computation.
-   * (this is the element on which aria-labelledby is set)
+   * E.g the element on which aria-labelledby is set
+   * or the <input> element being labelled by a <label> element.
    */
   public get referrer(): Option<Element> {
     return this._referrer;
   }
 
   /**
    * The element that is referenced during the name computation.
-   * (this is the target of the aria-labelledby attribute)
+   * E.g the target of the aria-labelledby attribute
+   * or the <label> element that labels an <input> element.
    */
   public get referred(): Option<Element> {
     return this._referred;
@@ -126,6 +128,13 @@ export class State implements Equatable, Serializable<State.JSON> {
    * @remarks
    * We currently have no way to clear references since we currently have no
    * use for it.
+   *
+   * @param referrer The element that is source of a labelled-by relation,
+   * e.g. an <input> element or an element with an aria-labelledby attribute.
+   *
+   * @param referred The element that is target of a labelled-by relation,
+   * e.g. a <label> element or an element referenced by an aria-labelled-by attribute
+   * on some other element.
    */
   public reference(referrer: Element, referred: Element): State {
     if (