HHH-18353 Reproducer

orm/hibernate-orm-6/src/test/java/org/hibernate/bugs/Author.java

@@ -0,0 +1,20 @@
+package org.hibernate.bugs;
+
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+
+@Entity
+public class Author {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.SEQUENCE)
+    private Long id;
+
+    public Long getId() {
+        return id;
+    }
+
+}

orm/hibernate-orm-6/src/test/java/org/hibernate/bugs/Book.java

@@ -0,0 +1,35 @@
+package org.hibernate.bugs;
+
+import jakarta.persistence.*;
+
+@Entity
+public class Book {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.SEQUENCE)
+    private long id;
+
+    @ManyToOne
+    private Author mainAuthor;
+
+    @ManyToOne
+    private Author contributedAuthor;
+
+    public Author getMainAuthor() {
+        return mainAuthor;
+    }
+
+    public Author getContributedAuthor() {
+        return contributedAuthor;
+    }
+
+    public Book setMainAuthor(Author value) {
+        mainAuthor = value;
+        return this;
+    }
+
+    public Book setContributedAuthor(Author value) {
+        contributedAuthor = value;
+        return this;
+    }
+}

orm/hibernate-orm-6/src/test/java/org/hibernate/bugs/JPAUnitTestCase.java

@@ -4,10 +4,18 @@
 import jakarta.persistence.EntityManagerFactory;
 import jakarta.persistence.Persistence;
 
+import jakarta.persistence.TypedQuery;
 import org.junit.After;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
 /**
  * This template demonstrates how to develop a test case for Hibernate ORM, using the Java Persistence API.
  */
@@ -28,10 +36,45 @@ public void destroy() {
 	// Entities are auto-discovered, so just add them anywhere on class-path
 	// Add your tests, using standard JUnit.
 	@Test
-	public void hhh123Test() throws Exception {
+	public void hhh18353Test() throws Exception {
 		EntityManager entityManager = entityManagerFactory.createEntityManager();
 		entityManager.getTransaction().begin();
-		// Do stuff...
+
+		/*
+			You can see first assertion will go through but second will fail.
+			Only different in queries is that one casts array elements explicitly,
+			while other tries to infer element types and assure all elements has are
+			of same type.
+		 */
+
+		Author author1 = entityManager.merge(new Author());
+		Author author2 = entityManager.merge(new Author());
+		Book book = entityManager.merge(new Book().setMainAuthor(author1).setContributedAuthor(author2));
+
+		Set<Long> expectedResults = Set.of(author1.getId(), author2.getId());
+
+		String castedQueryStr = "SELECT ARRAY(CAST(b.mainAuthor.id as Long), CAST(b.contributedAuthor.id as Long)) FROM Book b WHERE b = :book";
+		TypedQuery<Long[]> castedQuery = entityManager.createQuery(castedQueryStr, Long[].class);
+		castedQuery.setParameter("book", book);
+		Long[] castedResults = castedQuery.getSingleResult();
+
+		Assert.assertEquals(
+			"Expect found ids to be ones that we inserted into database",
+			expectedResults,
+			Set.of(castedResults)
+		);
+
+		String nonCastedQueryStr = "SELECT ARRAY(b.mainAuthor.id, b.contributedAuthor.id) FROM Book b WHERE b = :book";
+		TypedQuery<Long[]> nonCastedQuery = entityManager.createQuery(nonCastedQueryStr, Long[].class);
+		nonCastedQuery.setParameter("book", book);
+		Long[] nonCastedResults = nonCastedQuery.getSingleResult();
+
+		Assert.assertEquals(
+			"Expect found ids to be ones that we inserted into database",
+			expectedResults,
+			Set.of(nonCastedResults)
+		);
+
 		entityManager.getTransaction().commit();
 		entityManager.close();
 	}