HHH-19640 update-generated fields and forced version increments

When an entity has fields generated on update, we have to include
them in the UPDATE statement even for a "forced" version increment.
So we must skip an optimization.

Author: gavinking

hibernate-core/src/main/java/org/hibernate/persister/entity/mutation/UpdateCoordinatorStandard.java

@@ -169,15 +169,16 @@ public GeneratedValues update(
 			SharedSessionContractImplementor session) {
 		final EntityVersionMapping versionMapping = entityPersister().getVersionMapping();
 		if ( versionMapping != null ) {
-			final Supplier<GeneratedValues> generatedValuesAccess = handlePotentialImplicitForcedVersionIncrement(
-					entity,
-					id,
-					values,
-					oldVersion,
-					incomingDirtyAttributeIndexes,
-					session,
-					versionMapping
-			);
+			final var generatedValuesAccess =
+					handlePotentialImplicitForcedVersionIncrement(
+							entity,
+							id,
+							values,
+							oldVersion,
+							incomingDirtyAttributeIndexes,
+							session,
+							versionMapping
+					);
 			if ( generatedValuesAccess != null ) {
 				return generatedValuesAccess.get();
 			}
@@ -389,57 +390,71 @@ protected Supplier<GeneratedValues> handlePotentialImplicitForcedVersionIncremen
 			int[] incomingDirtyAttributeIndexes,
 			SharedSessionContractImplementor session,
 			EntityVersionMapping versionMapping) {
-		// handle case where the only value being updated is the version.
-		// we handle this case specially from `#coordinateUpdate` to leverage
-		// `#doVersionUpdate`
-		final boolean isSimpleVersionUpdate;
+		// Handle a case where the only value being updated is the version.
+		// We treat this case specially in `#coordinateUpdate` to leverage
+		// `#doVersionUpdate`.
 		final Object newVersion;
-
-		if ( incomingDirtyAttributeIndexes != null ) {
-			if ( incomingDirtyAttributeIndexes.length == 1
-					&& versionMapping.getVersionAttribute() == entityPersister().getAttributeMapping( incomingDirtyAttributeIndexes[0] ) ) {
-				// special case of only the version attribute itself as dirty
-				isSimpleVersionUpdate = true;
-				newVersion = values[ incomingDirtyAttributeIndexes[0]];
-			}
-			else if ( incomingDirtyAttributeIndexes.length == 0 && oldVersion != null ) {
-				isSimpleVersionUpdate = !versionMapping.areEqual(
-						values[ versionMapping.getVersionAttribute().getStateArrayPosition() ],
-						oldVersion,
-						session
-				);
-				newVersion = values[ versionMapping.getVersionAttribute().getStateArrayPosition()];
-			}
-			else {
-				isSimpleVersionUpdate = false;
-				newVersion = null;
-			}
-		}
-		else {
-			isSimpleVersionUpdate = false;
-			newVersion = null;
+		if ( hasUpdateGeneratedValues() ) {
+			// if we have any fields generated by the UPDATE event,
+			// then we have to include the generated fields in the
+			// update statement
+			return null;
 		}
-
-		if ( isSimpleVersionUpdate ) {
-			// we have just the version being updated - use the special handling
-			assert newVersion != null;
-			final GeneratedValues generatedValues = doVersionUpdate( entity, id, newVersion, oldVersion, session );
-			return () -> generatedValues;
+		else if ( incomingDirtyAttributeIndexes != null ) {
+			switch ( incomingDirtyAttributeIndexes.length ) {
+				case 1:
+					final int dirtyAttributeIndex = incomingDirtyAttributeIndexes[0];
+					final var versionAttribute = versionMapping.getVersionAttribute();
+					final var dirtyAttribute = entityPersister().getAttributeMapping( dirtyAttributeIndex );
+					if ( versionAttribute == dirtyAttribute ) {
+						// only the version attribute itself is dirty
+						newVersion = values[dirtyAttributeIndex];
+					}
+					else {
+						// the dirty field is some other field
+						return null;
+					}
+					break;
+				case 0:
+					if ( oldVersion != null ) {
+						newVersion = values[versionMapping.getVersionAttribute().getStateArrayPosition()];
+						if ( versionMapping.areEqual( newVersion, oldVersion, session ) ) {
+							return null;
+						}
+					}
+					else {
+						return null;
+					}
+					break;
+				default:
+					return null;
+			}
 		}
 		else {
 			return null;
 		}
+
+		// we have just the version being updated - use the special handling
+		assert newVersion != null;
+		final GeneratedValues generatedValues = doVersionUpdate( entity, id, newVersion, oldVersion, session );
+		return () -> generatedValues;
+	}
+
+	private boolean hasUpdateGeneratedValues() {
+		final var entityMetamodel = entityPersister().getEntityMetamodel();
+		return entityMetamodel.hasUpdateGeneratedValues()
+			|| entityMetamodel.hasPreUpdateGeneratedValues();
 	}
 
 	private static boolean isValueGenerated(Generator generator) {
 		return generator != null
-				&& generator.generatesOnUpdate()
-				&& generator.generatedOnExecution();
+			&& generator.generatesOnUpdate()
+			&& generator.generatedOnExecution();
 	}
 
 	private static boolean isValueGenerationInSql(Generator generator, Dialect dialect) {
 		assert isValueGenerated( generator );
-		return ( (OnExecutionGenerator) generator ).referenceColumnsInSql(dialect);
+		return ( (OnExecutionGenerator) generator ).referenceColumnsInSql( dialect );
 	}
 
 	/**