Reset plugin discovery when a module/theme is installed

The Needs Review Queue Bot → tested this issue. It either no longer applies to Drupal core, or fails the Drupal core commit checks. Therefore, this issue status is now "Needs work".

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Attached patch against Drupal 10.1.x

Patch #34 is not applied for Drupal 10.1.x so Inter-diff file is not added.

Checking patch core/lib/Drupal/Core/Entity/EntityTypeManager.php...
Checking patch core/lib/Drupal/Core/Extension/ThemeInstaller.php...
Hunk #1 succeeded at 300 (offset -4 lines).
Checking patch core/lib/Drupal/Core/Plugin/DefaultPluginManager.php...
Hunk #1 succeeded at 198 (offset 6 lines).
Checking patch core/modules/breakpoint/tests/src/Kernel/BreakpointDiscoveryTest.php...
error: while searching for:

  protected function setUp(): void {
    parent::setUp();
    \Drupal::service('theme_installer')->install(['breakpoint_theme_test']);
  }


error: patch failed: core/modules/breakpoint/tests/src/Kernel/BreakpointDiscoveryTest.php:24
error: core/modules/breakpoint/tests/src/Kernel/BreakpointDiscoveryTest.php: patch does not apply

1. +++ b/core/lib/Drupal/Core/Extension/ThemeInstaller.php
   @@ -300,6 +300,13 @@ public function uninstall(array $theme_list) {
   +    // Clear plugin manager caches.
   +    \Drupal::getContainer()
   +      ->get('plugin.cache_clearer')
   +      ->clearCachedDefinitions();
   

   This dependency should be injected - all the others are in class already.

2. +++ b/core/lib/Drupal/Core/Extension/ThemeInstaller.php
   @@ -300,6 +300,13 @@ public function uninstall(array $theme_list) {
   +
   +    $this->themeHandler->refreshInfo();
   

   Why is this necessary? Both install and uninstall are already calling $this->themeHandler->reset();

#34 states that #19 was addressed in #21, but it is not actually clear whether #21 meant that in a context of initially provided patch or in general:

That will clear the cache of definitions, which is fine. But that already happens due to a call to \Drupal::service('plugin.cache_clearer')->clearCachedDefinitions();.
This issue is about the actual discovery object itself.

So #19 is not actually addressed if the patch is not applied and it can be an easier solution.

https://www.drupal.org/node/3204271 → has a similar issue that is possible caused by already cached definitions.

For example, for LayoutPluginManager, adding of the cache tag based on the installed extensions resolves the issue

$this->setCacheBackend($cache_backend, $type, ['config:core.extension']);