1--TEST-- 2Bug GH-10583 (DateTime modify with tz pattern should not update linked timezone) 3--FILE-- 4<?php 5 6$dt = new DateTime('2015-01-01 00:00:00+00:00'); 7var_dump($dt->format('c')); 8var_dump($dt->modify('+1 s')->format('c')); 9 10$dt = new DateTimeImmutable('2015-01-01 00:00:00+00:00'); 11var_dump($dt->format('c')); 12var_dump($dt->modify('+1 s')->format('c')); 13?> 14--EXPECT-- 15string(25) "2015-01-01T00:00:00+00:00" 16string(25) "2015-01-01T00:00:00+00:00" 17string(25) "2015-01-01T00:00:00+00:00" 18string(25) "2015-01-01T00:00:00+00:00" 19