improve error messages when association targets non-entity type

hibernate-core/src/main/java/org/hibernate/boot/model/internal/BinderHelper.java

@@ -44,7 +44,6 @@ import org.hibernate.boot.spi.MetadataBuildingContext;
 import org.hibernate.boot.spi.PropertyData;
 import org.hibernate.dialect.DatabaseVersion;
 import org.hibernate.dialect.Dialect;
-import org.hibernate.internal.util.StringHelper;
 import org.hibernate.mapping.Any;
 import org.hibernate.mapping.AttributeContainer;
 import org.hibernate.mapping.BasicValue;

hibernate-core/src/main/java/org/hibernate/boot/model/internal/CollectionBinder.java

@@ -15,6 +15,7 @@ import java.util.Map;
 import java.util.Properties;
 import java.util.function.Supplier;
 
+import jakarta.persistence.Entity;
 import org.hibernate.AnnotationException;
 import org.hibernate.AssertionFailure;
 import org.hibernate.FetchMode;
@@ -97,7 +98,6 @@ import org.hibernate.internal.CoreMessageLogger;
 import org.hibernate.internal.util.collections.CollectionHelper;
 import org.hibernate.mapping.Any;
 import org.hibernate.mapping.Backref;
-import org.hibernate.mapping.BasicValue;
 import org.hibernate.mapping.CheckConstraint;
 import org.hibernate.mapping.Collection;
 import org.hibernate.mapping.Column;
@@ -2556,8 +2556,8 @@ public abstract class CollectionBinder {
 			boolean isCollectionOfEntities) {
 
 		if ( !isCollectionOfEntities) {
-			throw new AnnotationException( "Association '" + safeCollectionRole()
-							+ "' targets the type '" + elementType.getName() + "' which is not an '@Entity' type" );
+			throw new AnnotationException( "Association '" + safeCollectionRole() + "'"
+					+ targetEntityMessage( elementType ) );
 		}
 
 		joinColumns.setManyToManyOwnerSideEntityName( collectionEntity.getEntityName() );
@@ -2594,8 +2594,8 @@ public abstract class CollectionBinder {
 
 		if ( !isCollectionOfEntities) {
 			if ( property.isAnnotationPresent( ManyToMany.class ) || property.isAnnotationPresent( OneToMany.class ) ) {
-				throw new AnnotationException( "Association '" + safeCollectionRole()
-						+ "' targets the type '" + elementType.getName() + "' which is not an '@Entity' type" );
+				throw new AnnotationException( "Association '" + safeCollectionRole() + "'"
+						+ targetEntityMessage( elementType ) );
 			}
 			else if (isManyToAny) {
 				if ( propertyHolder.getJoinTable( property ) == null ) {
@@ -2607,13 +2607,20 @@ public abstract class CollectionBinder {
 				final JoinTable joinTableAnn = propertyHolder.getJoinTable( property );
 				if ( joinTableAnn != null && joinTableAnn.inverseJoinColumns().length > 0 ) {
 					throw new AnnotationException( "Association '" + safeCollectionRole()
-							+ " has a '@JoinTable' with 'inverseJoinColumns' and targets the type '"
-							+ elementType.getName() + "' which is not an '@Entity' type" );
+							+ " has a '@JoinTable' with 'inverseJoinColumns' and"
+							+ targetEntityMessage( elementType ) );
 				}
 			}
 		}
 	}
 
+	static String targetEntityMessage(XClass elementType) {
+		final String problem = elementType.isAnnotationPresent( Entity.class )
+				? " which does not belong to the same persistence unit"
+				: " which is not an '@Entity' type";
+		return " targets the type '" + elementType.getName() + "'" + problem;
+	}
+
 	private Class<? extends EmbeddableInstantiator> resolveCustomInstantiator(
 			XProperty property,
 			XClass propertyClass,

hibernate-core/src/main/java/org/hibernate/boot/model/internal/MapBinder.java

@@ -246,8 +246,8 @@ public class MapBinder extends CollectionBinder {
 			String mapKeyPropertyName) {
 		final PersistentClass associatedClass = persistentClasses.get( elementType.getName() );
 		if ( associatedClass == null ) {
-			throw new AnnotationException( "Association '" + safeCollectionRole()
-					+ "' targets the type '" + elementType.getName() + "' which is not an '@Entity' type" );
+			throw new AnnotationException( "Association '" + safeCollectionRole() + "'"
+					+ targetEntityMessage( elementType ) );
 		}
 		final Property mapProperty = findPropertyByName( associatedClass, mapKeyPropertyName );
 		if ( mapProperty == null ) {

hibernate-core/src/main/java/org/hibernate/boot/model/internal/OneToOneSecondPass.java

@@ -13,7 +13,6 @@ import org.hibernate.MappingException;
 import org.hibernate.annotations.LazyGroup;
 import org.hibernate.annotations.NotFoundAction;
 import org.hibernate.annotations.OnDeleteAction;
-import org.hibernate.annotations.common.reflection.XClass;
 import org.hibernate.annotations.common.reflection.XProperty;
 import org.hibernate.boot.spi.MetadataBuildingContext;
 import org.hibernate.boot.spi.PropertyData;
@@ -37,7 +36,6 @@ import static org.hibernate.boot.model.internal.BinderHelper.findPropertyByName;
 import static org.hibernate.boot.model.internal.BinderHelper.getPath;
 import static org.hibernate.boot.model.internal.ToOneBinder.bindForeignKeyNameAndDefinition;
 import static org.hibernate.boot.model.internal.ToOneBinder.defineFetchingStrategy;
-import static org.hibernate.boot.model.internal.ToOneBinder.getReferenceEntityName;
 import static org.hibernate.internal.util.StringHelper.qualify;
 import static org.hibernate.type.ForeignKeyDirection.FROM_PARENT;
 import static org.hibernate.type.ForeignKeyDirection.TO_PARENT;
@@ -53,19 +51,20 @@ public class OneToOneSecondPass implements SecondPass {
 	private final PropertyHolder propertyHolder;
 	private final NotFoundAction notFoundAction;
 	private final PropertyData inferredData;
-	private final XClass targetEntity;
 	private final OnDeleteAction onDeleteAction;
 	private final boolean optional;
 	private final String cascadeStrategy;
 	private final AnnotatedJoinColumns joinColumns;
+	private final String referencedEntityName;
+	private final boolean annotatedEntity;
 
 	public OneToOneSecondPass(
 			String mappedBy,
 			String ownerEntity,
-			@SuppressWarnings("unused") String ownerProperty,
 			PropertyHolder propertyHolder,
 			PropertyData inferredData,
-			XClass targetEntity,
+			String referencedEntityName,
+			boolean annotatedEntity,
 			NotFoundAction notFoundAction,
 			OnDeleteAction onDeleteAction,
 			boolean optional,
@@ -75,10 +74,11 @@ public class OneToOneSecondPass implements SecondPass {
 		this.ownerEntity = ownerEntity;
 		this.mappedBy = mappedBy;
 		this.propertyHolder = propertyHolder;
+		this.referencedEntityName = referencedEntityName;
 		this.buildingContext = buildingContext;
 		this.notFoundAction = notFoundAction;
 		this.inferredData = inferredData;
-		this.targetEntity = targetEntity;
+		this.annotatedEntity = annotatedEntity;
 		this.onDeleteAction = onDeleteAction;
 		this.optional = optional;
 		this.cascadeStrategy = cascadeStrategy;
@@ -94,7 +94,6 @@ public class OneToOneSecondPass implements SecondPass {
 		);
 		final String propertyName = inferredData.getPropertyName();
 		value.setPropertyName( propertyName );
-		final String referencedEntityName = getReferenceEntityName( inferredData, targetEntity, buildingContext );
 		value.setReferencedEntityName( referencedEntityName );
 		XProperty property = inferredData.getProperty();
 		defineFetchingStrategy( value, property, inferredData, propertyHolder );
@@ -136,10 +135,14 @@ public class OneToOneSecondPass implements SecondPass {
 
 	private void bindUnowned(Map<String, PersistentClass> persistentClasses, OneToOne oneToOne, Property property) {
 		oneToOne.setMappedByProperty( mappedBy );
-		final PersistentClass targetEntity = persistentClasses.get( oneToOne.getReferencedEntityName() );
+		final String targetEntityName = oneToOne.getReferencedEntityName();
+		final PersistentClass targetEntity = persistentClasses.get( targetEntityName );
 		if ( targetEntity == null ) {
+			final String problem = annotatedEntity
+					? " which does not belong to the same persistence unit"
+					: " which is not an '@Entity' type";
 			throw new MappingException( "Association '" + getPath( propertyHolder, inferredData )
-					+ "' targets unknown entity type '" + oneToOne.getReferencedEntityName() + "'" );
+					+ "' targets the type '" + targetEntityName + "'" + problem );
 		}
 		final Property targetProperty = targetProperty( oneToOne, targetEntity );
 		if ( targetProperty.getValue() instanceof OneToOne ) {
@@ -151,7 +154,7 @@ public class OneToOneSecondPass implements SecondPass {
 		else {
 			throw new AnnotationException( "Association '" + getPath( propertyHolder, inferredData )
 					+ "' is 'mappedBy' a property named '" + mappedBy
-					+ "' of the target entity type '" + oneToOne.getReferencedEntityName()
+					+ "' of the target entity type '" + targetEntityName
 					+ "' which is not a '@OneToOne' or '@ManyToOne' association" );
 		}
 		checkMappedByType(
@@ -235,13 +238,18 @@ public class OneToOneSecondPass implements SecondPass {
 				+ "' which does not exist in the target entity type '" + oneToOne.getReferencedEntityName() + "'" );
 	}
 
-	private void bindOwned(Map<String, PersistentClass> persistentClasses, OneToOne oneToOne, String propertyName, Property property) {
+	private void bindOwned(
+			Map<String, PersistentClass> persistentClasses,
+			OneToOne oneToOne,
+			String propertyName,
+			Property property) {
 		final ToOneFkSecondPass secondPass = new ToOneFkSecondPass(
 				oneToOne,
 				joinColumns,
 				true,
+				annotatedEntity,
 				propertyHolder.getPersistentClass(),
-				qualify( propertyHolder.getPath(), propertyName),
+				qualify( propertyHolder.getPath(), propertyName ),
 				buildingContext
 		);
 		secondPass.doSecondPass(persistentClasses);

hibernate-core/src/main/java/org/hibernate/boot/model/internal/ToOneBinder.java

@@ -9,6 +9,7 @@ package org.hibernate.boot.model.internal;
 import java.util.ArrayList;
 import java.util.List;
 
+import jakarta.persistence.Entity;
 import org.hibernate.AnnotationException;
 import org.hibernate.AssertionFailure;
 import org.hibernate.FetchMode;
@@ -36,7 +37,6 @@ import org.hibernate.mapping.SimpleValue;
 import org.hibernate.mapping.ToOne;
 
 import jakarta.persistence.Column;
-import jakarta.persistence.ConstraintMode;
 import jakarta.persistence.FetchType;
 import jakarta.persistence.ForeignKey;
 import jakarta.persistence.Id;
@@ -49,8 +49,6 @@ import jakarta.persistence.OneToOne;
 import jakarta.persistence.PrimaryKeyJoinColumn;
 import jakarta.persistence.PrimaryKeyJoinColumns;
 
-import static jakarta.persistence.ConstraintMode.NO_CONSTRAINT;
-import static jakarta.persistence.ConstraintMode.PROVIDER_DEFAULT;
 import static jakarta.persistence.FetchType.EAGER;
 import static jakarta.persistence.FetchType.LAZY;
 import static org.hibernate.boot.model.internal.BinderHelper.getCascadeStrategy;
@@ -229,6 +227,7 @@ public class ToOneBinder {
 				value,
 				joinColumns,
 				unique,
+				isTargetAnnotatedEntity( targetEntity, property, context ),
 				propertyHolder.getPersistentClass(),
 				fullPath,
 				context
@@ -254,6 +253,11 @@ public class ToOneBinder {
 		);
 	}
 
+	static boolean isTargetAnnotatedEntity(XClass targetEntity, XProperty property, MetadataBuildingContext context) {
+		final XClass target = isDefault( targetEntity, context ) ? property.getType() : targetEntity;
+		return target.isAnnotationPresent( Entity.class );
+	}
+
 	private static boolean handleSpecjSyntax(
 			AnnotatedJoinColumns columns,
 			PropertyData inferredData,
@@ -490,6 +494,7 @@ public class ToOneBinder {
 				notFoundAction,
 				onDelete == null ? null : onDelete.action(),
 				getTargetEntity( inferredData, context ),
+				property,
 				propertyHolder,
 				inferredData,
 				nullIfEmpty( oneToOne.mappedBy() ),
@@ -510,6 +515,7 @@ public class ToOneBinder {
 			NotFoundAction notFoundAction,
 			OnDeleteAction cascadeOnDelete,
 			XClass targetEntity,
+			XProperty annotatedProperty,
 			PropertyHolder propertyHolder,
 			PropertyData inferredData,
 			String mappedBy,
@@ -528,10 +534,10 @@ public class ToOneBinder {
 			final OneToOneSecondPass secondPass = new OneToOneSecondPass(
 					mappedBy,
 					propertyHolder.getEntityName(),
-					propertyName,
 					propertyHolder,
 					inferredData,
-					targetEntity,
+					getReferenceEntityName( inferredData, targetEntity, context ),
+					isTargetAnnotatedEntity( targetEntity, annotatedProperty, context ),
 					notFoundAction,
 					cascadeOnDelete,
 					optional,

hibernate-core/src/main/java/org/hibernate/boot/model/internal/ToOneFkSecondPass.java

@@ -34,11 +34,13 @@ public class ToOneFkSecondPass extends FkSecondPass {
 	private final boolean unique;
 	private final String path;
 	private final String entityClassName;
+	private final boolean annotatedEntity;
 
 	public ToOneFkSecondPass(
 			ToOne value,
 			AnnotatedJoinColumns columns,
 			boolean unique,
+			boolean annotatedEntity,
 			PersistentClass persistentClass,
 			String path,
 			MetadataBuildingContext buildingContext) {
@@ -48,6 +50,7 @@ public class ToOneFkSecondPass extends FkSecondPass {
 		this.unique = unique;
 		this.entityClassName = persistentClass.getClassName();
 		this.path = entityClassName != null ? path.substring( entityClassName.length() + 1 ) : path;
+		this.annotatedEntity = annotatedEntity;
 	}
 
 	@Override
@@ -95,13 +98,17 @@ public class ToOneFkSecondPass extends FkSecondPass {
 	@Override
 	public void doSecondPass(java.util.Map<String, PersistentClass> persistentClasses) throws MappingException {
 		if ( value instanceof ManyToOne ) {
-			//TODO: move this validation logic to a separate ManyToOnSecondPass
+			//TODO: move this validation logic to a separate ManyToOneSecondPass
 			//      for consistency with how this is handled for OneToOnes
 			final ManyToOne manyToOne = (ManyToOne) value;
-			final PersistentClass targetEntity = persistentClasses.get( manyToOne.getReferencedEntityName() );
+			final String targetEntityName = manyToOne.getReferencedEntityName();
+			final PersistentClass targetEntity = persistentClasses.get( targetEntityName );
 			if ( targetEntity == null ) {
+				final String problem = annotatedEntity
+						? " which does not belong to the same persistence unit"
+						: " which is not an '@Entity' type";
 				throw new AnnotationException( "Association '" + qualify( entityClassName, path )
-						+ "' targets an unknown entity named '" + manyToOne.getReferencedEntityName() + "'" );
+						+ "' targets the type '" + targetEntityName + "'" + problem );
 			}
 			manyToOne.setPropertyName( path );
 			createSyntheticPropertyReference(