Started to increase the phpstan level

src/Entity/Attachments/Attachment.php

@@ -37,6 +37,7 @@ use LogicException;
 /**
  * Class Attachment.
  * @see \App\Tests\Entity\Attachments\AttachmentTest
+ * @template-covariant  T of AttachmentContainingDBElement
  */
 #[ORM\Entity(repositoryClass: AttachmentRepository::class)]
 #[ORM\InheritanceType('SINGLE_TABLE')]
@@ -75,9 +76,9 @@ abstract class Attachment extends AbstractNamedDBElement
 
     /**
      * @var string The class of the element that can be passed to this attachment. Must be overridden in subclasses.
-     *
+     * @phpstan-var class-string<T>
      */
-    protected const ALLOWED_ELEMENT_CLASS = '';
+    protected const ALLOWED_ELEMENT_CLASS = AttachmentContainingDBElement::class;
 
     /**
      * @var string|null the original filename the file had, when the user uploaded it
@@ -101,6 +102,7 @@ abstract class Attachment extends AbstractNamedDBElement
 
     /**
      * ORM mapping is done in subclasses (like PartAttachment).
+     * @phpstan-param T|null $element
      */
     protected ?AttachmentContainingDBElement $element = null;
 
@@ -116,7 +118,7 @@ abstract class Attachment extends AbstractNamedDBElement
     public function __construct()
     {
         //parent::__construct();
-        if ('' === static::ALLOWED_ELEMENT_CLASS) {
+        if (AttachmentContainingDBElement::class === static::ALLOWED_ELEMENT_CLASS) {
             throw new LogicException('An *Attachment class must override the ALLOWED_ELEMENT_CLASS const!');
         }
     }

src/Entity/Attachments/AttachmentContainingDBElement.php

@@ -31,13 +31,17 @@ use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\Mapping as ORM;
 use Symfony\Component\Serializer\Annotation\Groups;
 
+/**
+ * @template-covariant AT of Attachment
+ */
 #[ORM\MappedSuperclass]
 abstract class AttachmentContainingDBElement extends AbstractNamedDBElement implements HasMasterAttachmentInterface, HasAttachmentsInterface
 {
     use MasterAttachmentTrait;
 
     /**
-     * @var Attachment[]|Collection
+     * @var Collection<int, Attachment>
+     * @phpstan-var Collection<int, AT>
      * ORM Mapping is done in subclasses (e.g. Part)
      */
     #[Groups(['full'])]
@@ -76,7 +80,7 @@ abstract class AttachmentContainingDBElement extends AbstractNamedDBElement impl
     /**
      * Gets all attachments associated with this element.
      *
-     * @return Attachment[]|Collection
+     * @return Collection<Attachment>
      */
     public function getAttachments(): Collection
     {

src/Entity/Attachments/AttachmentType.php

@@ -35,6 +35,7 @@ use Symfony\Component\Validator\Constraints as Assert;
 /**
  * Class AttachmentType.
  * @see \App\Tests\Entity\Attachments\AttachmentTypeTest
+ * @extends AbstractStructuralDBElement<AttachmentTypeAttachment, AttachmentTypeParameter>
  */
 #[ORM\Entity(repositoryClass: StructuralDBElementRepository::class)]
 #[ORM\Table(name: '`attachment_types`')]

src/Entity/Attachments/AttachmentTypeAttachment.php

@@ -27,6 +27,7 @@ use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;
 
 /**
  * A attachment attached to an attachmentType element.
+ * @extends Attachment<AttachmentType>
  */
 #[UniqueEntity(['name', 'attachment_type', 'element'])]
 #[ORM\Entity]

src/Entity/Attachments/CategoryAttachment.php

@@ -28,6 +28,7 @@ use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;
 
 /**
  * An attachment attached to a category element.
+ * @extends Attachment<Category>
  */
 #[UniqueEntity(['name', 'attachment_type', 'element'])]
 #[ORM\Entity]