[desrosj]

WordPress 7.2 (currently in beta) adds support for PHP 8.6. This PR adds PHP 8.6 variants so the ecosystem can test against them during the 7.2 pre-release cycle. In #986 there was some interest in exploring PHP pre-release support "assuming WordPress upstream supports the given pre-release version", and that's the case here.

Changes

• versions.sh / versions.json: 8.6-rc is added to phpVersions for the beta channel only, so the FROM values (php:8.6-rc-<variant>) and image tags (beta-php8.6-rc-*) are correct without any RC-specific logic. latest (7.1.x) and cli are unchanged.
• Dockerfile.template:
  • PHP 8.6 images no longer ship pear/pecl or a compiled-in mbstring (Drop --with-pear with PHP 8.6 php#1654), so for 8.6 mbstring is installed with docker-php-ext-install (plus libonig-dev / oniguruma-dev).
  • imagick is skipped for PHP 8.6. No imagick release compiles against 8.6: 3.8.1 still uses zval_dtor() and XtOffsetOf(), which were removed in 8.6 (php-src UPGRADING.INTERNALS). The XtOffsetOf fix (XtOffsetOf is removed in 8.6, use standard C offsetof Imagick/imagick#795) is merged but unreleased; the zval_dtor fix (The zval_dtor() alias of zval_ptr_dtor_nogc() has been removed in php 8.6 (master) Imagick/imagick#768) is still open. Installing imagick without pecl is also pending Migrate to pie for installing imagick #1001. WordPress falls back to GD for image processing in the meantime.

Rendered output for PHP 8.2–8.5 and cli is byte-identical to what's currently committed, and the generated tags for all existing entries are unchanged.

Notes

• PHP 8.6 base images are now ZTS for every variant (remove zts, instead all images are always built as zts (8.6+) php#1686), unlike 8.2–8.5.
• Follow-ups:
  • When PHP 8.6 is GA: rename 8.6-rc to 8.6 (images move to php:8.6-* and tags to php8.6).
  • When WordPress 7.2.0 is released: beta will match latest and be skipped by generate-stackbrew-library.sh, so 8.6 needs to move into the shared phpVersions list at that point or the 8.6 images will disappear.

Still to do

• Run ./apply-templates.sh and commit the generated beta/php8.6-rc/* directories
• Build and smoke-test apache, fpm and fpm-alpine on 8.6

AI Disclaimer

This PR was generated with Claude Opus 5.5 and manually reviewed by me.

Closes #1027

[tianon]

I think we end up with a lot of nice properties for "free" if we just embed "8.6-rc" here instead of handling RC-specific logic all over -- then we don't need the is_php_rc function at all, for example, and the FROM values and the image tags are automatically correct (php8.6-rc instead of just php8.6).

I think we also don't need the version gate, because we only support a single version of WordPress (#701). 🙇 👀

[desrosj]

Great call, thanks! Updated in 0ee2ef5:

• 8.6-rc is now embedded directly in phpVersions (so is_php_rc is gone and the FROM/tags come out as php:8.6-rc-* / beta-php8.6-rc-*)
• the WordPress version gate is replaced with a plain beta-only condition. I've noted the follow-ups in the description: renaming to 8.6 at GA, and moving it into the shared list once 7.2.0 ships (since beta gets skipped when it matches latest).

I think we also don't need the version gate, because we only support a single version of WordPress (#701).

Given how large the expanded matrix is, this seems reasonable. I'm afraid I don't really know how these images are used in practice. If these are used by folks in production environments it would be great to ship some security updates, even if only for the last handful of versions. I'll follow up over on #701!