Respect timezone offset given after timezone name

Description

Hello 👋 With the following code:

<?php
$date = new DateTime('2024-11-03 01:30:00 America/Toronto -0500');

echo $date->format('Y-m-d H:i:s e O');

Resulted in this output:

2024-11-03 01:30:00 America/Toronto -0400

https://3v4l.org/qg4aN

But I expected this output instead:

2024-11-03 01:30:00 America/Toronto -0500

Both exist, and it's possible to obtain the first with:

$date = new DateTime('@1730611800');
$date->setTimezone(new DateTimeZone('America/Toronto'));

As per the test above, it sounds like whatever offset coming after a named timezone like "America/Toronto" is ignored, so we can have the timezone set by name or by offset but we cannot have both while it's actually needed to distinguish 2 possibly different moments during DST such as Nov 3rd 1:30 -0400 and Nov 3rd 1:30 -0500 which both exist in America/Toronto.

A possible implementation would to:

• Detect both named timezone and offset timezone,
• if only one is present:
  • no change: keep current behavior
• if both are present:
  • and the current date-time + timezone offset exist in the given timezone city
    • apply both
  • but the current date-time + timezone offset is invalid
    • ignore offset (i.e. current behavior)

Thanks 🙏

PHP Version

PHP 8.3.12 and also 8.4.0-dev (78767de197d1b2a6d2dd2757258b4c642bda8052)

Reproduce the behavior with the DateTime constructor using the America/Toronto name and -0500 offset, then compare it with the @timestamp and setTimezone example. Trace the date-time parsing entry point and add coverage for both valid November 3, 2024 offsets; done means the explicit offset is respected when it identifies an existing local time and current behavior remains for invalid combinations.