File validation logic from #3221793 broke backwards compatibility

I think the solution should be that we catch the plugin not found and trigger a deprecation error and carry on.

Webform isn't using it for file validation, its using it for theming.

It probably should use something else, but yes, this is a change in behaviour

The code from 10.1

foreach ($validators as $function => $args) {
    if (function_exists($function)) {
      array_unshift($args, $file);
      $errors = array_merge($errors, call_user_func_array($function, $args));
    }
  }

As you can see it silently ignored non existent functions

For the open thread to add a trigger_error, not sure if we can reuse an existing CR since this was covered somewhere else?

I think we can add something about passing arbitrary data in the form array under '#upload_validators' is deprecated to the existing CR https://www.drupal.org/node/3363700. As that CR is published, do we need to do it after this is committed?

Just for consistency can the issue summary be updated to include steps, proposed solution, etc.

Updated the issue summary.

I think given the thing we're deprecating here already doesn't work in 10.2.x, it's fine to update the CR before commit here.

Updated https://www.drupal.org/node/3363700

I think the deprecation message needs to mention the string being used as a plugin ID so that this is easier to debug.

Applied both those suggestions.

Appears feedback has been addressed.

Since this is a regression assumed it's fine that deprecation is 10.2

Issue credits

Committed to 11.x and backported to 10.2.x

Verified the CR changes https://www.drupal.org/node/3363700/revisions/view/13228435/13360530

Thanks all