From 4fac597229f3acafcc4cf504af742f9a3f120eae Mon Sep 17 00:00:00 2001
From: Christian Beikov <christian.beikov@gmail.com>
Date: Mon, 13 Jan 2025 15:27:40 +0100
Subject: [PATCH] HHH-7135 Disallow @MapsId on unowned @OneToOne

---
 .../org/hibernate/boot/model/internal/ColumnsBuilder.java    | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hibernate-core/src/main/java/org/hibernate/boot/model/internal/ColumnsBuilder.java b/hibernate-core/src/main/java/org/hibernate/boot/model/internal/ColumnsBuilder.java
index 1cb4a6e9ca75..7c87992f6077 100644
--- a/hibernate-core/src/main/java/org/hibernate/boot/model/internal/ColumnsBuilder.java
+++ b/hibernate-core/src/main/java/org/hibernate/boot/model/internal/ColumnsBuilder.java
@@ -289,6 +289,11 @@ private JoinColumn[] getJoinColumnAnnotations(MemberDetails property, PropertyDa
 	 */
 	AnnotatedColumns overrideColumnFromMapperOrMapsIdProperty(PropertyData override) {
 		if ( override != null ) {
+			final OneToOne oneToOneAnn = override.getAttributeMember().getDirectAnnotationUsage( OneToOne.class );
+			if ( oneToOneAnn != null && nullIfEmpty( oneToOneAnn.mappedBy() ) != null ) {
+				throw new AnnotationException( "Property '" + getPath( propertyHolder, override )
+											+ "' is annotated '@MapsId' but has no columns due to its '@OneToOne(mappedBy)' usage" );
+			}
 			final AnnotatedJoinColumns joinColumns = buildExplicitJoinColumns( override.getAttributeMember(), override );
 			return joinColumns == null
 					? buildDefaultJoinColumnsForToOne( override.getAttributeMember(), override )