From e5335b984b79508c7d644fb77a0bd407a4feaa45 Mon Sep 17 00:00:00 2001
From: Domenic Denicola <d@domenic.me>
Date: Tue, 31 Oct 2023 17:14:48 +0900
Subject: [PATCH] Fix PromiseRejectionEvent's promise attribute

As discovered in https://github.com/whatwg/streams/issues/1298#issuecomment-1774668957, Promise<T> is actually not an appropriate type for it.
---
 source | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/source b/source
index 093339b50c2..b728736a4e4 100644
--- a/source
+++ b/source
@@ -105721,12 +105721,12 @@ dictionary <dfn dictionary>ErrorEventInit</dfn> : <span>EventInit</span> {
 interface <dfn interface>PromiseRejectionEvent</dfn> : <span>Event</span> {
   <span data-x="dom-Event-constructor">constructor</span>(DOMString type, <span>PromiseRejectionEventInit</span> eventInitDict);
 
-  readonly attribute Promise&lt;any&gt; <span data-x="dom-PromiseRejectionEvent-promise">promise</span>;
+  readonly attribute <span data-x="idl-object">object</span> <span data-x="dom-PromiseRejectionEvent-promise">promise</span>;
   readonly attribute any <span data-x="dom-PromiseRejectionEvent-reason">reason</span>;
 };
 
 dictionary <dfn dictionary>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
-  required Promise&lt;any&gt; promise;
+  required <span data-x="idl-object">object</span> promise;
   any reason;
 };</code></pre>
 
@@ -105734,6 +105734,12 @@ dictionary <dfn dictionary>PromiseRejectionEventInit</dfn> : <span>EventInit</sp
   data-x="dom-PromiseRejectionEvent-promise">promise</code></dfn> attribute must return the value it
   was initialized to. It represents the promise which this notification is about.</p>
 
+  <p class="note">Because of how Web IDL conversion rules for <code
+  data-x="">Promise&lt;<var>T</var>></code> types always wrap the input into a new promise, the
+  <code data-x="dom-PromiseRejectionEvent-promise">promise</code> attribute is of type <code
+  data-x="idl-object">object</code> instead, which is more appropriate for representing an opaque
+  handle to the original promise object.</p>
+
   <p>The <dfn attribute for="PromiseRejectionEvent"><code
   data-x="dom-PromiseRejectionEvent-reason">reason</code></dfn> attribute must return the value it
   was initialized to. It represents the rejection reason for the promise.</p>