Refactor out theme hook suggestion building from ThemeManager::render() into a separate function.

Set method protected and internal, also addressed #19

Seems like a straight forward refactor.

Committed and pushed d21fd5d28e to 11.x (10.2.x). Thanks!

As a straight refactor I don't think this needs a CR, I suspect people will never override it but it does make the parent method slightly shorter.

Automatically closed - issue fixed for 2 weeks with no activity.

This change broke our site when switching to Drupal 10.2. Indeed, we've implemented hook_theme_suggestions_HOOK_alter() in a way that is not following the docs. We did:

function mytheme_suggestions_page_title_alter(array &$suggestions, array &$variables): void {
  ...
  $variables['foo'] = $bar;
}

Note that $variables is passed by reference which doesn't follow the signature of hook_theme_suggestions_HOOK_alter(). But that is still possible with hook implementation as, with hooks, there's no strong, enforcement on signature (like with interfaces/classes).

As, buildThemeHookSuggestions() doesn't pass $variables by reference, the change is lost.

I wonder if this could be considered a regression. What if there are more such unorthodox hook implementations out in the wild?

Opened 🐛 [D10.2 regression] Theme suggestions cannot alter variables anymore Active