Clear Caches button should not be part of Performance form

This form is already covered by functional tests that use it to clear cache and save config:

web/core/modules/block/tests/src/Functional/BlockInvalidRegionTest.php
web/core/modules/menu_ui/tests/src/Functional/MenuLinkReorderTest.php
web/core/modules/config_translation/tests/src/Functional/ConfigTranslationCacheTest.php
web/core/tests/Drupal/FunctionalTests/Installer/InstallerTranslationTest.php

There are contrib modules that form_alter the system_performance_settings form, but I'm not aware of any that alter the cache clear button. Purge (purge_ui) alters the cache duration options and captcha adds a warning as a new form element.

The config_readonly test that checks for the read-only warning will still pass.

Patch not applying in drupal-9.3.x-dev showing error while going to apply patch
i have added in settings.php
$settings['config_readonly'] = TRUE;

Checking patch core/modules/system/src/Controller/PerformanceController.php...
error: core/modules/system/src/Controller/PerformanceController.php:
Checking patch core/modules/system/src/Form/ClearCacheForm.php...
error: core/modules/system/src/Form/ClearCacheForm.php:
Checking patch core/modules/system/src/Form/PerformanceForm.php...
Checking patch core/modules/system/system.routing.yml...

@vikashsoni I'm not sure what you're doing wrong, but this works for me:

$ git clone https://git.drupalcode.org/project/drupal.git
...
$ cd drupal
$ git checkout 9.3.x
$ curl -s 'https://www.drupal.org/files/issues/2022-01-13/drupal-3258433-2-split_performance_form.patch' | patch --dry-run -p1
checking file core/modules/system/src/Controller/PerformanceController.php
checking file core/modules/system/src/Form/ClearCacheForm.php
checking file core/modules/system/src/Form/PerformanceForm.php
checking file core/modules/system/system.routing.yml
$ curl -s 'https://www.drupal.org/files/issues/2022-01-13/drupal-3258433-2-split_performance_form.patch' | patch -p1
patching file core/modules/system/src/Controller/PerformanceController.php
patching file core/modules/system/src/Form/ClearCacheForm.php
patching file core/modules/system/src/Form/PerformanceForm.php
patching file core/modules/system/system.routing.yml
$ git status
On branch 9.3.x
Your branch is up to date with 'origin/9.3.x'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   core/modules/system/src/Form/PerformanceForm.php
	modified:   core/modules/system/system.routing.yml

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	core/modules/system/src/Controller/PerformanceController.php
	core/modules/system/src/Form/ClearCacheForm.php

This issue is being reviewed by the kind folks in Slack, #need-reveiw-queue. We are working to keep the size of Needs Review queue [2700+ issues] to around 400 (1 month or less), following Review a patch or merge require as a guide.

Applying patch #2 I see no visual regression as the cache clear button is still there and functional

Reviewing the code the changes look good.
I see appropriate typehints

Do think something like this should have a change record so tagging for that.

I'll work on the CR.

Added draft change record https://www.drupal.org/node/3350667

Will mark this but think we could change this to a feature request and add test coverage.

I'm not sure whether this needs test coverage or not, but let's check the following:

1. Is there any existing test coverage of the page?

2. Manual testing to confirm there's no visual regression.

#15.1 = There are still references to admin/config/development/performance in BlockInvalidRegionTest and ConfigTranslationCacheTest where the "Clear cache" button is pressed.

#15.2 Attaching screenshots but no visual regression.

Before

After

It is pleasant to find an issue with an up to date issue summary and a short one too! I read the IS and the comments and I find that all the questions have been answered.

I tested the patch, using the steps in the issue summary. I can confirm that the patch fixes the problem. However, this is re-testing the patch on 9.3.x instead of 10.1.x.

I also found other tests that use the 'Clear all caches' button.

$ git grep 'submitForm.*Clear all caches' | awk -F: '{print $1}' | sort -u | nl
     1  core/modules/block/tests/src/Functional/BlockInvalidRegionTest.php
     2  core/modules/config_translation/tests/src/Functional/ConfigTranslationCacheTest.php
     3  core/modules/menu_ui/tests/src/Functional/MenuLinkReorderTest.php

Next, I read the CR. I think it needs some improvement and here is what I found:

• "This could impact any custom or contrib modules using hook_form_alter to modify the Clear Caches button behavior, although there are no known examples at present.". And yet the steps to reproduce show the problem with a contrib module. So, that statement seems to be incorrect. Or, am I missing something?
• "The Clear Caches button". It will be clearer if this uses the actual text of the button, 'Clear all caches'.
• The first sentence should be split into two to make it easier to understand.
• The version field should be completed.

I am tagging for CR update.

I read the patch. Everything looks in order and the comments are easy to understand.

So, this just needs the updates to the CR and then it should be good to go.

CR changes look good. Hopefully makes it for 10.1

Committed 73c3cea and pushed to 10.1.x. Thanks!

Published the change record.