Deprecate drupal_process_states()

+++ b/core/lib/Drupal/Core/Render/Renderer.php
@@ -401,7 +402,7 @@ protected function doRender(&$elements, $is_root_call = FALSE) {
     if (!empty($elements['#states'])) {
-      drupal_process_states($elements);
+      FormHelper::processStates($elements);

As it more about any elements then maybe better to move it to \Drupal\Core\Render\Element?

Reroll + added tests

Function does not return value, fixed test

Yes, that raised in drupal attributes and we need separate issue to make it consistent and another issue to fix coding standards

Btw my test is wrong because it passed in #7

Link to "dot" #2677532-146: Move drupal_check_incompatibility() functionality to a new Dependency class and Version component

The period at the end of deprecation messages is inconsistent throughout core. It's an accident of English that incorrect but valid URL elements are also grammatically correct.

It's fine either way, until there's a coder rule for it, though I like it without the period.

1. +++ b/core/lib/Drupal/Core/Form/FormHelper.php
   @@ -67,4 +68,135 @@ protected static function processStatesArray(array &$conditions, $search, $repla
   +   * A "state" means a certain property on a DOM element, such as "visible" or
   +   * "checked". A state can be applied to an element, depending on the state of
   

   +1 on more docs.

2. +++ b/core/lib/Drupal/Core/Form/FormHelper.php
   @@ -67,4 +68,135 @@ protected static function processStatesArray(array &$conditions, $search, $repla
   +  public static function processStates(array &$elements) {
   

   When this is in, FormHelper will have three methods: processStates(), rewriteStatesSelector(), and processStatesArray().

   processStatesArray() is protected so we get a clue as to how (not to) use it, but it's still not very clear how it's different from processStates(array $array). Especially with this remarkably unhelpful summary line: "Helper function for self::rewriteStatesSelector()."

   rewriteStatesSelector() could have a more descriptive docblock, too.

   This is mostly a nit, tho if I encountered this helper without knowing it's history I'd be confused. Maybe this nit is out of scope here.

NW based on #12.

Updated doc blocks to be more clear. I did my best)

1. +++ b/core/includes/common.inc
   @@ -589,16 +589,14 @@ function drupal_js_defaults($data = NULL) {
   + * @deprecated in Drupal 8.7.0 and will be removed before Drupal 9.0.0. Use
   ...
   +  @trigger_error('drupal_process_states() is deprecated in Drupal 8.7.0 and will be removed before Drupal 9.0.0. Use \Drupal\Core\Form\FormHelper::processStates() instead. See https://www.drupal.org/node/3000069', E_USER_DEPRECATED);
   

   CS issue, needs to be fixed.
   Also version need to be updated 8.7.0 => 8.8.0.

2. +++ b/core/tests/Drupal/KernelTests/Core/Render/RendererLegacyTest.php
   @@ -37,4 +38,47 @@ public function providerAttributes() {
   +   * @expectedDeprecation drupal_process_states() is deprecated in Drupal 8.7.0 and will be removed before Drupal 9.0.0. Use \Drupal\Core\Form\FormHelper::processStates() instead. See https://www.drupal.org/node/3000069
   

   Same here

Re-roll & fix CS

Seems to be a unrelated test fail. RTBC once ✅

Also updated change record.

Committed 2a5c62d and pushed to 8.8.x. Thanks!