Problem/Motivation
Drupal 9's maximum PHP version is PHP 8.1.
Drupal 10's minimum PHP version is PHP 8.1, maximum is PHP 8.2 (so far).
PHP 8.1 has security support until 25 Nov 2024
PHP 8.2 has active support until 8 December 2024 and security support until 8 Dec 2025.
Assuming Drupal 10 is released in the second half of 2024 (see #3330791: Policy: target Drupal 11 for August 2024 with a December 2024 fallback), then PHP 8.1 will be close to the end of security support, and PHP 8.2 will be actively supported (just).
At the moment, dependencies have only just added PHP 8.2 support, so it's too early for any of them to require it, but this could change in the next year, for example Symfony could decide to require PHP 8.2 in Symfony 7.
I think it will be too early to require PHP 8.3, given we'd only be adding support for that at the end of 2023.
I don't think we have a technical reason to require PHP 8.2, it would just be about aligning with dependencies and PHP's release cycle, and having less PHP versions to support as Drupal 11 gets older.
Steps to reproduce
Proposed resolution
Either:
1. Decide to keep the minimum version on PHP 8.1 for now, but be prepared to raise it in the next 12 months if a dependency does. This runs the risk of a dependency raising their minimum after we're six months to release, but if they don't it would allow someone whose just installed Drupal 10 on PHP 8.1 to update to Drupal 11 without having to update their hosting first.
2. Decide pre-emptively to make the minimum version PHP 8.2 to give hosting providers and site owners the longest possible notice.