From 5d043915fe6c1d6f3f8ce040eb27e4143be8ccdb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Go=C5=82e=CC=A8biowski-Owczarek?=
 <m.goleb@gmail.com>
Date: Mon, 28 Apr 2025 11:37:48 +0200
Subject: [PATCH] Deferred: Don't warn on setting getStackHook to the
 getErrorHook value

Don't warn if `jQuery.Deferred.getStackHook` is set to the value of
`jQuery.Deferred.getErrorHook`. This is to facilitate plugins supporting both
jQuery <3.7 and older without triggering Migrate warnings and without requiring
complex logic parsing `jQuery.fn.jquery`.

Ref gh-577
---
 src/jquery/deferred.js       | 10 +++++++---
 test/unit/jquery/deferred.js |  7 ++++++-
 warnings.md                  |  4 ++--
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/jquery/deferred.js b/src/jquery/deferred.js
index bb78cd3e..4fb22844 100644
--- a/src/jquery/deferred.js
+++ b/src/jquery/deferred.js
@@ -88,10 +88,14 @@ Object.defineProperty( jQuery.Deferred, "getStackHook", {
 	},
 	set: function( newValue ) {
 		if ( jQuery.migrateIsPatchEnabled( "deferred-getStackHook" ) ) {
-			migrateWarn( "deferred-getStackHook",
-				"jQuery.Deferred.getStackHook is deprecated; " +
+
+			// Only warn if `getErrorHook` wasn't set to the same value first.
+			if ( jQuery.Deferred.getErrorHook !== newValue ) {
+				migrateWarn( "deferred-getStackHook",
+					"jQuery.Deferred.getStackHook is deprecated; " +
 					"use jQuery.Deferred.getErrorHook" );
-			jQuery.Deferred.getErrorHook = newValue;
+				jQuery.Deferred.getErrorHook = newValue;
+			}
 		} else {
 			unpatchedGetStackHookValue = newValue;
 		}
diff --git a/test/unit/jquery/deferred.js b/test/unit/jquery/deferred.js
index 07a0ec9a..86ae218e 100644
--- a/test/unit/jquery/deferred.js
+++ b/test/unit/jquery/deferred.js
@@ -77,7 +77,7 @@ QUnit.test( "jQuery.Deferred.getStackHook - getter, no getErrorHook", function(
 } );
 
 QUnit.test( "jQuery.Deferred.getStackHook - setter", function( assert ) {
-	assert.expect( 5 );
+	assert.expect( 6 );
 
 	var exceptionHookSpy,
 		done = assert.async();
@@ -91,6 +91,11 @@ QUnit.test( "jQuery.Deferred.getStackHook - setter", function( assert ) {
 			"getStackHook mirrors getErrorHook (setter)" );
 	} );
 
+	expectNoWarning( assert, "jQuery.Deferred.getStackHook - setter", 1, function() {
+		var mockFn = function() {};
+		jQuery.Deferred.getStackHook = jQuery.Deferred.getErrorHook = mockFn;
+	} );
+
 	expectWarning( assert, "asyncHook from jQuery.Deferred.getStackHook reported",
 			1, function() {
 		jQuery.Deferred.getStackHook = function() {
diff --git a/warnings.md b/warnings.md
index e6979b68..f3adecbf 100644
--- a/warnings.md
+++ b/warnings.md
@@ -319,6 +319,6 @@ See jQuery-ui [commit](https://github.com/jquery/jquery-ui/commit/c0093b599fcd58
 
 ### \[deferred-getStackHook\] JQMIGRATE: jQuery.Deferred.getStackHook is deprecated; use jQuery.Deferred.getErrorHook
 
-**Cause:** `jQuery.Deferred.getStackHook` was originally created to pass the stack trace from before an async barrier to report when a user error (like calling a non-existing function) causes a promise to be rejected. However, passing a stack trace doesn't take source maps into account, so we started advising to pass the whole error object. To make it clearer, we also renamed the API to `jQuery.Deferred.getErrorHook`. The legacy alias will be removed in jQuery 4.0.0
+**Cause:** `jQuery.Deferred.getStackHook` was originally created to pass the stack trace from before an async barrier to report when a user error (like calling a non-existing function) causes a promise to be rejected. However, passing a stack trace doesn't take source maps into account, so we started advising to pass the whole error object. To make it clearer, we also renamed the API to `jQuery.Deferred.getErrorHook`. The legacy alias will be removed in jQuery 4.0.0.
 
-**Solution:** Rename all usage of `jQuery.Deferred.getStackHook` to `jQuery.Deferred.getErrorHook`. If you previously assigned a function returning an error stack to `jQuery.Deferred.getStackHook` or `jQuery.Deferred.getErrorHook`, change it to return a full error object.
+**Solution:** Rename all usage of `jQuery.Deferred.getStackHook` to `jQuery.Deferred.getErrorHook`. If you previously assigned a function returning an error stack to `jQuery.Deferred.getStackHook` or `jQuery.Deferred.getErrorHook`, change it to return a full error object. If you aim to still support jQuery <3.7, assign the hook to `jQuery.Deferred.getErrorHook` first and only later to `jQuery.Deferred.getStackHook` to avoid a Migrate warning.