From 2cb36cab728faa4e10a06e7fb4ed02179f4b05ab Mon Sep 17 00:00:00 2001
From: Dion Hulse <dd32@git.wordpress.org>
Date: Thu, 18 Jan 2018 05:17:23 +0000
Subject: [PATCH] General: Allow `wp_list_pluck()` to operate on arrays of
 references without overwriting the referenced items.

Fixes #16895.


git-svn-id: https://develop.svn.wordpress.org/trunk@42527 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/class-wp-list-util.php       | 10 ++--
 tests/phpunit/tests/functions/listFilter.php | 50 ++++++++++++++++++++
 2 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/src/wp-includes/class-wp-list-util.php b/src/wp-includes/class-wp-list-util.php
index 0fbefd08e4..da2a897987 100644
--- a/src/wp-includes/class-wp-list-util.php
+++ b/src/wp-includes/class-wp-list-util.php
@@ -140,6 +140,8 @@ class WP_List_Util {
 	 *               `$list` will be preserved in the results.
 	 */
 	public function pluck( $field, $index_key = null ) {
+		$newlist = array();
+
 		if ( ! $index_key ) {
 			/*
 			 * This is simple. Could at some point wrap array_column()
@@ -147,11 +149,14 @@ class WP_List_Util {
 			 */
 			foreach ( $this->output as $key => $value ) {
 				if ( is_object( $value ) ) {
-					$this->output[ $key ] = $value->$field;
+					$newlist[ $key ] = $value->$field;
 				} else {
-					$this->output[ $key ] = $value[ $field ];
+					$newlist[ $key ] = $value[ $field ];
 				}
 			}
+
+			$this->output = $newlist;
+
 			return $this->output;
 		}
 
@@ -159,7 +164,6 @@ class WP_List_Util {
 		 * When index_key is not set for a particular item, push the value
 		 * to the end of the stack. This is how array_column() behaves.
 		 */
-		$newlist = array();
 		foreach ( $this->output as $value ) {
 			if ( is_object( $value ) ) {
 				if ( isset( $value->$index_key ) ) {
diff --git a/tests/phpunit/tests/functions/listFilter.php b/tests/phpunit/tests/functions/listFilter.php
index 364b31d99d..a736d62b3f 100644
--- a/tests/phpunit/tests/functions/listFilter.php
+++ b/tests/phpunit/tests/functions/listFilter.php
@@ -210,6 +210,56 @@ class Tests_Functions_ListFilter extends WP_UnitTestCase {
 		);
 	}
 
+	/**
+	 * @ticket 16895
+	 */
+	function test_wp_list_pluck_containing_references() {
+		$ref_list = array(
+			& $this->object_list['foo'],
+			& $this->object_list['bar'],
+		);
+
+		$this->assertInstanceOf( 'stdClass', $ref_list[0] );
+		$this->assertInstanceOf( 'stdClass', $ref_list[1] );
+
+		$list = wp_list_pluck( $ref_list, 'name' );
+		$this->assertEquals(
+			array(
+				'foo',
+				'bar',
+			),
+			$list
+		);
+
+		$this->assertInstanceOf( 'stdClass', $ref_list[0] );
+		$this->assertInstanceOf( 'stdClass', $ref_list[1] );
+	}
+
+	/**
+	 * @ticket 16895
+	 */
+	function test_wp_list_pluck_containing_references_keys() {
+		$ref_list = array(
+			& $this->object_list['foo'],
+			& $this->object_list['bar'],
+		);
+
+		$this->assertInstanceOf( 'stdClass', $ref_list[0] );
+		$this->assertInstanceOf( 'stdClass', $ref_list[1] );
+
+		$list = wp_list_pluck( $ref_list, 'name', 'id' );
+		$this->assertEquals(
+			array(
+				'f' => 'foo',
+				'b' => 'bar',
+			),
+			$list
+		);
+
+		$this->assertInstanceOf( 'stdClass', $ref_list[0] );
+		$this->assertInstanceOf( 'stdClass', $ref_list[1] );
+	}
+
 	function test_filter_object_list_nested_array_and() {
 		$list = wp_filter_object_list( $this->object_list, array( 'field4' => array( 'blue' ) ), 'AND' );
 		$this->assertEquals( 1, count( $list ) );