From f584b5755ad66c5017fbf003ba98bd529afba9da Mon Sep 17 00:00:00 2001
From: John Blackbourn <johnbillion@git.wordpress.org>
Date: Thu, 5 Jul 2018 23:10:01 +0000
Subject: [PATCH] Date/Time: Add support for the `c` and `r` shorthand formats
 in `date_i18n()`.

Props Rarst, pbearne

Fixes #20973


git-svn-id: https://develop.svn.wordpress.org/trunk@43434 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/functions.php         |  3 +++
 tests/phpunit/tests/date/dateI18n.php | 22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index 9fba7917d6..8ae58299d6 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -107,6 +107,9 @@ function date_i18n( $dateformatstring, $timestamp_with_offset = false, $gmt = fa
 	 */
 	$req_format = $dateformatstring;
 
+	$dateformatstring = preg_replace( "/(?<!\\\\)c/", DATE_W3C, $dateformatstring );
+	$dateformatstring = preg_replace( "/(?<!\\\\)r/", DATE_RFC2822, $dateformatstring );
+
 	if ( ( ! empty( $wp_locale->month ) ) && ( ! empty( $wp_locale->weekday ) ) ) {
 		$datemonth            = $wp_locale->get_month( date( 'm', $i ) );
 		$datemonth_abbrev     = $wp_locale->get_month_abbrev( $datemonth );
diff --git a/tests/phpunit/tests/date/dateI18n.php b/tests/phpunit/tests/date/dateI18n.php
index 283d82adbd..c3dc1a6e77 100644
--- a/tests/phpunit/tests/date/dateI18n.php
+++ b/tests/phpunit/tests/date/dateI18n.php
@@ -83,4 +83,26 @@ class Tests_Date_I18n extends WP_UnitTestCase {
 
 		$this->assertEquals( $datetime->format( $timezone_formats ), date_i18n( $timezone_formats ) );
 	}
+
+	/**
+	 * @dataProvider data_formats
+	 * @ticket 20973
+	 */
+	public function test_date_i18n_handles_shorthand_formats( $short, $full ) {
+		$this->assertEquals( date_i18n( $full ), date_i18n( $short ) );
+		$this->assertEquals( $short, date_i18n( '\\' . $short ) );
+	}
+
+	public function data_formats() {
+		return array(
+			array(
+				'c',
+				'Y-m-d\TH:i:sP',
+			),
+			array(
+				'r',
+				'D, d M Y H:i:s O',
+			),
+		);
+	}
 }