matchEntityPropsForScalar clones entity data definition, but property definitions are not reset

Overview

Encountered this when working with Acquia DAM and Content Templates. There was a field on the Article content type that referenced Acquia DAM media types and the normal image/video media types. Canvas was failing over the bundle fields on the Acquia DAM media types. I feel like there may be another way to reproduce, but this was how we triggered.

When loading a form for a component a 500 error was returned:

Error 500: Field acquia_dam_alt_text does not exist on entity:media:acquia_dam_image_asset entities.

But the field definitely exists in the bundle's field definitions. In \Drupal\canvas\ShapeMatcher\JsonSchemaFieldInstanceMatcher::matchEntityPropsForScalar there is logic to map bundles from a reference fields settings:

            // When >1 bundle is specified, the above only matched base fields.
            // Iterate over all possible target bundles, set each on a clone of
            // $target, and hence repeat the same process as above — but exclude
            // base fields that are re-matched.
            // @see \Drupal\Core\Entity\TypedData\EntityDataDefinition::getPropertyDefinitions()
            $target_bundles = $field_definition->getItemDefinition()->getSettings()['handler_settings']['target_bundles'] ?? [];
            if (count($target_bundles) > 1) {
              $base_field_names = array_keys($target->getPropertyDefinitions());
              foreach ($target_bundles as $target_bundle) {
                assert($target->getBundles() === NULL);

This code clones the entity data definition and sets the bundle explicitly for the target bundle. The problem is that cloning EntityDataDefinition does not reset the values in \Drupal\Core\TypedData\ComplexDataDefinitionBase::$propertyDefinitions which act as an object cache.

Proposed resolution

The fix is to skip cloning and create a new value object:

$bundle_specific_target = EntityDataDefinition::create($target->getEntityTypeId(), $target_bundle);

User interface changes