HHH-18871 Nested NativeQuery Mappings

hibernate-core/src/main/java/org/hibernate/metamodel/mapping/internal/PluralAttributeMappingImpl.java

@@ -807,7 +807,6 @@ private TableGroup createRootTableGroupJoin(
 			SqlAstCreationState creationState) {
 		final CollectionPersister collectionDescriptor = getCollectionDescriptor();
 		final SqlAstJoinType joinType = determineSqlJoinType( lhs, requestedJoinType, fetched );
-		final SqlAliasBase sqlAliasBase = creationState.getSqlAliasBaseGenerator().createSqlAliasBase( getSqlAliasStem() );
 
 		final TableGroup tableGroup;
 		if ( collectionDescriptor.isOneToMany() ) {
@@ -818,7 +817,7 @@ private TableGroup createRootTableGroupJoin(
 					fetched,
 					addsPredicate,
 					explicitSourceAlias,
-					sqlAliasBase,
+					explicitSqlAliasBase,
 					creationState
 			);
 		}
@@ -830,7 +829,7 @@ private TableGroup createRootTableGroupJoin(
 					fetched,
 					addsPredicate,
 					explicitSourceAlias,
-					sqlAliasBase,
+					explicitSqlAliasBase,
 					creationState
 			);
 		}

hibernate-core/src/main/java/org/hibernate/query/sql/internal/ResultSetMappingProcessor.java

@@ -270,7 +270,11 @@ else if ( ownerResult instanceof DynamicFetchBuilderLegacy dynamicFetchBuilderLe
 		else {
 			throw new AssertionFailure( "Unexpected fetch builder" );
 		}
-		return path.append( fetchBuilder.getFetchable().getFetchableName() );
+		final String fetchableName = fetchBuilder.getFetchable().getFetchableName();
+		if ( path.getLocalName().equals( fetchableName ) ) {
+			return path;
+		}
+		return path.append( fetchableName );
 	}
 
 	private DynamicResultBuilderEntityStandard createSuffixedResultBuilder(

hibernate-core/src/test/java/org/hibernate/orm/test/query/NativeQueryNestedTree.java

@@ -0,0 +1,103 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.query;
+
+import jakarta.persistence.*;
+import org.hibernate.cfg.AvailableSettings;
+import org.hibernate.testing.orm.junit.*;
+import org.junit.jupiter.api.Test;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+/**
+ * This reproduces an issue in Hibernate 6 parsing native queries.
+ */
+@DomainModel(
+		annotatedClasses = {
+				NativeQueryNestedTree.TreeNode.class
+		}
+)
+@ServiceRegistry(
+		settings = {
+				@Setting(name = AvailableSettings.SHOW_SQL, value = "true"),
+				@Setting(name = AvailableSettings.HBM2DDL_AUTO, value = "create")
+		}
+)
+@SessionFactory
+@JiraKey(value = "HHH-18871")
+public class NativeQueryNestedTree {
+
+	@Test
+	public void test(SessionFactoryScope scope) {
+		// We want to make sure 'Could not locate TableGroup' no longer is thrown
+		assertDoesNotThrow( () ->
+			scope.inTransaction( session ->
+				session.createNativeQuery( """
+					SELECT {t.*}, {t2.*}, {t3.*}
+					FROM TREE t
+					INNER JOIN tree t2 ON t2.parentident = t.ident
+					INNER JOIN tree t3 ON t3.parentident = t2.ident
+				""" )
+					.addEntity( "t", TreeNode.class )
+					.addJoin( "t2", "t.children" )
+					.addJoin( "t3", "t2.children" )
+					.list()
+			)
+		);
+
+		assertDoesNotThrow(() ->
+			scope.inTransaction(session ->
+				session.createNativeQuery("""
+						SELECT {t.*}, {t2.*}, {t3.*}, {t4.*}
+						FROM tree t
+						INNER JOIN tree t2 ON t2.parentident = t.ident
+						INNER JOIN tree t3 ON t3.parentident = t2.ident
+						INNER JOIN tree t4 ON t4.parentident = t3.ident
+					""")
+					.addEntity("t", TreeNode.class)
+					.addJoin("t2", "t.children")
+					.addJoin("t3", "t2.children")
+					.addJoin("t4", "t3.children")
+					.list()
+			)
+		);
+
+		// Let's get crazy
+		assertDoesNotThrow(() ->
+			scope.inTransaction(session ->
+				session.createNativeQuery("""
+						SELECT {t.*}, {t2.*}, {t3.*}, {t4.*}, {t5.*}
+						FROM tree t
+						INNER JOIN tree t2 ON t2.parentident = t.ident
+						INNER JOIN tree t3 ON t3.parentident = t2.ident
+						INNER JOIN tree t4 ON t4.parentident = t3.ident
+						INNER JOIN tree t5 ON t5.parentident = t4.ident
+					""")
+					.addEntity("t", TreeNode.class)
+					.addJoin("t2", "t.children")
+					.addJoin("t3", "t2.children")
+					.addJoin("t4", "t3.children")
+					.addJoin("t5", "t4.children")
+					.list()
+			)
+		);
+	}
+
+	@Entity(name = "TreeNode")
+	@Table(name = "TREE")
+	public static class TreeNode {
+		@ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
+		@JoinColumn(name = "parentident")
+		private TreeNode parent;
+		@OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
+		private Set<TreeNode> children = new HashSet<TreeNode>();
+		@Id
+		@GeneratedValue
+		private long ident;
+	}
+}