[meta] Eliminate core .theme files [#3554670]

Problem/Motivation

Themes can now be OOP, let's convert what we can.

Then let's move remaining procedural functions. ⁷

Steps to reproduce

Open theme files.

Proposed resolution

Add procedural test coverage: #3579629: Add procedural hooks to test theme to test collection and invoking legacy hooks

Core themes
Convert the missed hooks and move the remaining functions to the correct hook class

claro.theme #3579899: Remove remaining claro.theme functions

_claro_convert_link_to_action_link
_claro_preprocess_file_and_image_widget
claro_system_module_invoked_library_info_alter
claro_system_module_invoked_theme_registry_alter

olivero.theme #3579903: Eliminate Olivero and three test .theme files

_olivero_hex_to_hsl

stable9.theme #3579903: Eliminate Olivero and three test .theme files

stable9_preprocess_item_list__search_results
stable9_preprocess_views_view

Test themes #3579903: Eliminate Olivero and three test .theme files

access_test.theme

Keep this file

test_installer_theme.theme

test_installer_theme_form_install_select_language_form_alter
Test converting this

test_missing_base_theme.theme

Delete this file

views_test_checkboxes_theme.theme

views_test_checkboxes_theme_form_views_exposed_form_alter
Convert this hook

Identify if there are any functions that cannot be in classes.

Remaining tasks

N/A

User interface changes

N/A

Introduced terminology

N/A

API changes

N/A

Data model changes

N/A

Release notes snippet

N/A

Comment	File	Size	Author
#28	3554670-nr-bot_tytw1vgd.txt	91 bytes	needs-review-queue-bot

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3554670-conversionv3

changes, plain diff MR !13992

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11.x

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3554670-meta-convert-themes

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3554670-conversionv2

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About issue forks

Comments

Comment #1

28 October 2025 at 02:08

nicxvan created an issue. See original summary.

Comment #2

nicxvan commented 28 October 2025 at 02:12

Issue summary:

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Comment #3

nicxvan commented 28 October 2025 at 03:45

Issue summary:

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Comment #4

28 October 2025 at 04:05

nicxvan opened merge request !13600

Comment #5

berdir

German

Switzerland

commented 28 October 2025 at 06:27

I'd really prefer to do the big themes properly grouped and not just one big hooks class. And those in a dedicated issue.

We know better now how to group them and otherwise it will result in another chain of follow ups

Comment #6

nicxvan commented 28 October 2025 at 13:08

At first I agreed with you, I was really just testing how this worked with themes for rector.

However, I think we should do this automatically for a few reasons.

1. Test rector on themes
2. We've seen how long even just simple organization can take in the queue, let's at least remove the .theme files I think followups will be simpler for themes
3. I think with the comment issue this is pretty much done and will be ready for testing

Comment #7

7 November 2025 at 14:47

nicxvan changed the visibility of the branch 11.x to hidden.

Comment #8

7 November 2025 at 14:51

nicxvan changed the visibility of the branch 3554670-meta-convert-themes to hidden.

Comment #9

7 November 2025 at 14:51

nicxvan closed merge request !13600

Comment #10

28 November 2025 at 21:55

nicxvan changed the visibility of the branch 3554670-conversionv2 to hidden.

Comment #11

28 November 2025 at 22:28

nicxvan opened merge request !13992

Comment #12

nicxvan commented 29 November 2025 at 03:13

Issue summary:

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Comment #13

nicxvan commented 29 November 2025 at 03:20

Issue summary:

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Comment #14

nicxvan commented 29 November 2025 at 03:37

Issue summary:

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Comment #15

nicxvan commented 29 November 2025 at 03:53

Issue summary:

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Comment #16

berdir

German

Switzerland

commented 29 November 2025 at 20:42

The fail in InstallerTranslationTest happens on /admin/config/regional/language and the exception backtrace is this:

InvalidArgumentException: Class "Drupal\test_theme\Hook\TestThemeHooks" does not exist. in /var/www/html/core/lib/Drupal/Core/DependencyInjection/ClassResolver.php:32
Stack trace:
#0 /var/www/html/core/lib/Drupal/Core/Utility/CallableResolver.php(100): Drupal\Core\DependencyInjection\ClassResolver->getInstanceFromDefinition()
#1 /var/www/html/core/lib/Drupal/Core/Theme/ThemeManager.php(592): Drupal\Core\Utility\CallableResolver->getCallableFromDefinition()
#2 /var/www/html/core/lib/Drupal/Core/Theme/ThemeManager.php(552): Drupal\Core\Theme\ThemeManager->getImplementationsForTheme()
#3 /var/www/html/core/lib/Drupal/Core/Theme/ThemeManager.php(620): Drupal\Core\Theme\ThemeManager->alterForTheme()
#4 /var/www/html/core/lib/Drupal/Core/Render/ElementInfoManager.php(135): Drupal\Core\Theme\ThemeManager->alter()
#5 /var/www/html/core/lib/Drupal/Core/Render/ElementInfoManager.php(71): Drupal\Core\Render\ElementInfoManager->buildInfo()
#6 /var/www/html/core/lib/Drupal/Core/Form/FormBuilder.php(865): Drupal\Core\Render\ElementInfoManager->getInfo()
#7 /var/www/html/core/lib/Drupal/Core/Form/FormBuilder.php(305): Drupal\Core\Form\FormBuilder->prepareForm()
#8 /var/www/html/core/lib/Drupal/Core/Form/FormBuilder.php(244): Drupal\Core\Form\FormBuilder->buildForm()
#9 /var/www/html/core/lib/Drupal/Core/Entity/DraggableListBuilderTrait.php(121): Drupal\Core\Form\FormBuilder->getForm()
#10 /var/www/html/core/lib/Drupal/Core/Entity/Controller/EntityListController.php(23): Drupal\Core\Config\Entity\DraggableListBuilder->render()
#11 [internal function]: Drupal\Core\Entity\Controller\EntityListController->listing()
#12 /var/www/html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array()
#13 /var/www/html/core/lib/Drupal/Core/Render/Renderer.php(634): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#14 [internal function]: Drupal\Core\Render\Renderer::Drupal\Core\Render\{closure}()
#15 /var/www/html/core/lib/Drupal/Core/Render/Renderer.php(635): Fiber->start()
#16 /var/www/html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(121): Drupal\Core\Render\Renderer->executeInRenderContext()
#17 /var/www/html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext()
#18 /var/www/html/vendor/symfony/http-kernel/HttpKernel.php(183): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#19 /var/www/html/vendor/symfony/http-kernel/HttpKernel.php(76): Symfony\Component\HttpKernel\HttpKernel->handleRaw()
#20 /var/www/html/core/lib/Drupal/Core/StackMiddleware/Session.php(53): Symfony\Component\HttpKernel\HttpKernel->handle()
#21 /var/www/html/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle()
#22 /var/www/html/core/lib/Drupal/Core/StackMiddleware/ContentLength.php(28): Drupal\Core\StackMiddleware\KernelPreHandle->handle()
#23 /var/www/html/core/modules/page_cache/src/StackMiddleware/PageCache.php(118): Drupal\Core\StackMiddleware\ContentLength->handle()
#24 /var/www/html/core/modules/page_cache/src/StackMiddleware/PageCache.php(92): Drupal\page_cache\StackMiddleware\PageCache->pass()
#25 /var/www/html/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(48): Drupal\page_cache\StackMiddleware\PageCache->handle()
#26 /var/www/html/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle()
#27 /var/www/html/core/lib/Drupal/Core/StackMiddleware/AjaxPageState.php(53): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle()
#28 /var/www/html/core/lib/Drupal/Core/StackMiddleware/StackedHttpKernel.php(54): Drupal\Core\StackMiddleware\AjaxPageState->handle()
#29 /var/www/html/core/lib/Drupal/Core/DrupalKernel.php(745): Drupal\Core\StackMiddleware\StackedHttpKernel->handle()
#30 /var/www/html/index.php(19): Drupal\Core\DrupalKernel->handle()
#31 {main}

The test has protected $defaultTheme = 'test_theme'; but on that page, \Drupal::getContainer()->getParameter('container.themes') only has stark. Changing the test to use stark gets the test passed that line but fails later due to theme specific checks.

I'm guessing installer tests don't set up the theme properly, they set it as the active one without properly installing it.

Comment #17

nicxvan commented 30 November 2025 at 01:11

Thank you!

// Ensure the default theme is installed.
$container->get('theme_installer')->install([$this->defaultTheme], TRUE);

Is in the installerTestBase and adding the install during the test doesn't fix it either. I'll have to investigate further.

Edit, just to see where this was going wrong I added:
$themes = \Drupal::getContainer()->getParameter('container.themes');
Right before where the test dies and I see:

stark
stable9
starterkit_theme
test_theme

I'll try reviewing from the other direction.

Comment #18

nicxvan commented 30 November 2025 at 04:16

Ok I dug in more to the Theme settings failure, and it's a weird one, it's because test_theme_theme isn't the admin theme so the hook adding the field doesn't run.

Setting it to the admin theme works manually testing, I tried:

    $edit['admin_theme'] = $theme;
    $this->drupalGet('admin/appearance');
    $this->submitForm($edit, 'Save configuration');

and

    \Drupal::configFactory()
      ->getEditable('system.theme')
      ->set('admin', $theme)
      ->save();

Neither work in the test.

Reverting the hook does work though.

Comment #19

nicxvan commented 1 December 2025 at 15:11

I found the theme settings failure, we call it directly:

 // Call theme-specific settings.
        $function = $theme . '_form_system_theme_settings_alter';
        if (function_exists($function)) {
          $function($form, $form_state);
        }

I'll revert that one conversion for now and create a follow up.

Comment #20

nicxvan commented 1 December 2025 at 15:14

#3560833: Create better way to manage theme setting alters I'm going to revert that conversion here.

Comment #21

nicxvan commented 1 December 2025 at 15:33

Also reverted starterkit in favor of: #3560844: Update starterkit and GenerateThemeTests to handle OOP hooks

Comment #22

nicxvan commented 1 December 2025 at 15:41

Title:

[meta] Convert themes to OOP

» Convert themes to OOP

I also reverted test theme for #3560851: Convert test_theme to OOP

Comment #23

nicxvan commented 1 December 2025 at 15:53

Issue summary:

View changes

Comment #24

phenaproxima

he/him

English

Massachusetts

commented 1 December 2025 at 20:36

Status:

Active

» Needs review

I am not entirely qualified to sign off on this, but I do like how the actual change is like 10 lines long, and the rest of this is just removing .theme files in favor of classes. That's really nice to see.

Maybe a comment in the theme registry, to clarify what it's doing, would be nice? It's hard to grok without a lot of background context loaded into one's brain.

Comment #25

nicxvan commented 2 December 2025 at 04:53

Status:

Needs review

» Active

Thank you, I addressed all of your feedback.

I think it's actually better to keep the change in #3556794: preprocess_HOOK__candidates in themes can be assigned to module invoke maps since several of the conversions here test that better than the test in that dedicated issue.

This should be ready for review again.

Comment #26

catch

he/him

English

commented 5 January 2026 at 06:29

Status:

Active

» Needs review

Comment #27

5 January 2026 at 06:29

Version:

11.x-dev

» main

Drupal core is now using the main branch as the primary development branch. New developments and disruptive changes should now be targeted to the main branch.

Comment #28

needs-review-queue-bot commented 23 January 2026 at 12:40

Status:

Needs review

» Needs work

Status	File	Size
new	3554670-nr-bot_tytw1vgd.txt	91 bytes

The Needs Review Queue Bot tested this issue. It no longer applies to Drupal core. Therefore, this issue status is now "Needs work".

This does not mean that the patch necessarily needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

Consult the Drupal Contributor Guide to find step-by-step guides for working with issues.

Comment #29

nicxvan commented 25 February 2026 at 03:53

Title:	Convert themes to OOP	» [meta] Eliminate core .theme files
Issue summary:	View changes

Comment #30

nicxvan commented 25 February 2026 at 03:54

Issue summary:

View changes

Comment #31

25 February 2026 at 05:04

nicxvan changed the visibility of the branch 3554670-conversionv3 to hidden.

Comment #32

nicxvan commented 25 February 2026 at 05:04

Converted this to a meta, I created three issues for the remaining core themes.

I'll create follow ups for the .theme files once those are all committed.

Comment #33

28 February 2026 at 04:40

nicxvan closed merge request !13992

Comment #34

nicxvan commented 5 March 2026 at 15:22

Just a couple more!

Comment #35

nicxvan commented 17 March 2026 at 03:44

Comment #36

nicxvan commented 17 March 2026 at 03:47

Issue summary:

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Comment #37

nicxvan commented 17 March 2026 at 04:02

Issue summary:

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Comment #38

nicxvan commented 17 March 2026 at 04:06

Issue summary:

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Comment #39

berdir

German

Switzerland

commented 17 March 2026 at 09:47

The claro_system functions I think shouldn't be in claro at all I think, they are currently called by system module, but all of that and the related helpers should be moved to toolbar, which is moving to contrib, it's overlapping with the system.module function removal issue. I think it makes sense to do them together.