WP-CLI 3.0.0 / PHP version requirement tracking issue

[swissspidy]

Right now we have a few issues scattered across multiple repositories, so I figured I'd create one to combine them all.

To-do

• Update requirements on the wp-cli.org website.

Expected breaking changes in v3.0.0

• Current issues in the 3.0.0 milestone

PHP version bump

In our next release, we’ll bump the minimum PHP version to 7.2.24+.

Previous groundwork for that in v2.12.0

• PHP 8.4 Compatibility #5946
  • The mustache/mustache library remains a blocker. A PR exists to ensure PHP 8.4 compatibility, but there is no activity. -> We should consider forking or look for an alternative.
    • Alternatives often require newer PHP versions
• Require Behat v3.15.0+ wp-cli-tests#228
  • The new Behat version works on 8.4 without warnings, but requires PHP 7.2
• Tests: Failing install on PHP 5.6 due to conflict with symfony/process #6018
  • A dependency of wp-cli/package-command can no longer be installed on 5.6 because of security advisories
• Smarter auto-updating re. PHP requirements #6004
  • We need to harden the updater so that older PHP versions can still update to the latest possible compatible version. This obviously needs to happen before 3.0.0.

With this bump we can:

• Drop support for older WordPress versions, likely WordPress 4.8 and below
  • According to https://make.wordpress.org/core/handbook/references/php-compatibility-and-wordpress-versions/, WordPress 4.9 is the first version to support PHP 7.2
  • We can check whether older versions like WordPress 4.7 still work ok with that version though. There might be some wiggle room.
  • Most notably, we'll stop testing the WordPress 3.7 & PHP 5.6 combination
  • Consider increasing minimum supported WordPress version #5705
• Remove a lot of old compatibility code throughout the codebase
  • For example the wp-settings-cli.php file in wp-cli/wp-cli, which is for WP < 4.6
• Slowly adopt new language features such as new type declarations, null coalescing operator, and much more
  • Keep public APIs as-is to avoid unnecessary breaking changes
  • Do this only where it makes sense
• Remove the https://github.com/wp-cli/process fork again
• Use PHPStan 1.x
  • Add PHPStan support wp-cli-tests#203
• Use the oldest still maintained PHPUnit version, PHPUnit 8, requires PHP 7.2, so we'll be able to use that
• Re-Add roave/security-advisories after PHP requirement bump #6087

To do this bump:

1. Update test matrix in https://github.com/wp-cli/.github to remove anything below PHP 7.2. Add new entries with PHP 7.2 & WP 4.9 or so.
2. Bump requirement in wp-cli/wp-cli-bundle
   • https://github.com/wp-cli/wp-cli-bundle/blob/44e61272f9deaa0825165dd5472d6c601d0ec85c/composer.json#L11
   • https://github.com/wp-cli/wp-cli-bundle/blob/44e61272f9deaa0825165dd5472d6c601d0ec85c/composer.json#L53
   • ... and many more places
3. Bump requirement in wp-cli/wp-cli

   • wp-cli/composer.json

     Line 11 in 3ca317a

     "php": "^5.6 || ^7.0 || ^8.0",

   • wp-cli/manifest.json

     Line 2 in 3ca317a

     "requires_php": "5.6.0"

     • With this, wp cli update will not show you the new version if you're not on PHP 7.2+

   • wp-cli/php/boot-fs.php

     Line 10 in 3ca317a

     if ( version_compare( PHP_VERSION, '5.6.0', '<' ) ) {

   • ... and many more places
4. Bump requirements in all the packages
5. ... and probably many more steps

[swissspidy]

Regarding the Mustache library, we'll probably just fork it for now.

But I'm still wondering why WP_CLI\Dispatcher\Subcommand->validate_args -> WP_CLI\Dispatcher\CompositeCommand->get_longdesc() -> WP_CLI\Dispatcher\CompositeCommand->get_global_params() actually needs Mustache just to get the global params for args validation. I think that could be done differently/simpler.
Then those PHP warnings would only really be shown in Help_Command, making them a lot less annoying.

[swissspidy]

WP-CLI v2.12.0 is now out of the door 🎉

https://make.wordpress.org/cli/2025/05/07/wp-cli-v2-12-0-release-notes/

We had to add some workarounds like forking https://github.com/wp-cli/process to have issue-free installation on PHP 5.6 still. With the next release, we’ll bump the minimum PHP version to 7.2.24+, which will allow us to get rid of all these workarounds again.

[schlessera]

Given that WP 4.9 would be the lowest WordPress version to officially support PHP 7.2 and given that I would not want to put ourselves in the position where we need to test even more functionality from outside of the scope of WP-CLI itself, I'd say we raise the WP minimum version to 4.9+ with release 3.0.0.

This will drastically simplify our testing setup, allow us to remove a lot of polyfills/compat code and random cruft and make it smoother to work on new features.