[php-src] Issue #11215: The Problem about Unixtime Convert

Issue: https://github.com/php/php-src/issues/11215 Author: stevennight ### Description # The following code: ```php <?php #date_default_timezone_set("PRC"); date_default_timezone_set("Asia/Shanghai"); echo strtotime('1988-04-18') . PHP_EOL; echo strtotime('1988-04-19') . PHP_EOL; echo strtotime('1988-04-19') - strtotime('1988-04-18') . PHP_EOL; echo strtotime('1988-04-17') . PHP_EOL; echo strtotime('1988-04-18') . PHP_EOL; echo strtotime('1988-04-18') - strtotime('1988-04-17') . PHP_EOL; echo strtotime('1988-04-11') . PHP_EOL; echo strtotime('1988-04-10') . PHP_EOL; echo strtotime('1988-04-11') - strtotime('1988-04-10') . PHP_EOL; ``` # Resulted in this output: 577292400 577378800 86400 **577209600 577292400 82800** 576691200 576604800 86400 # But I expected this output instead: The convert from '1988-04-18' to timestamp maybe wrong when I set the timezone to PRC or Asia/Shanghai.(Other timezone like 'Asia/Hong_kong', 'Asia/Tokyo', it seem running well with this test data) The interval between 1998-04-17 and 1998-04-18 only 82800 seconds(23 hours). I try to convert it with java or mysql are got the timestamp is '577296000' instead of '577292400'. When I try to convert with '2023-05-10', the result is correct, it's same to mysql result. I'm very confused, can you help me please? thanks. ### PHP Version 7.4.27 But it seem Other version with this problem too, I checked on https://onlinephp.io with 8.2.6 and other. ### Operating System _No response_