HHH-18069 NullPointerException when unioning partition results

Author: dreab8

hibernate-core/src/main/java/org/hibernate/query/sqm/sql/BaseSqmToSqlAstConverter.java

@@ -1989,6 +1989,8 @@ public QueryGroup visitQueryGroup(SqmQueryGroup<?> queryGroup) {
 					(SqmAliasedNodeCollector) lastPoppedProcessingState.getSqlExpressionResolver()
 			);
 
+			final FromClauseIndex firstQueryPartIndex = lastPoppedFromClauseIndex;
+
 			visitOrderByOffsetAndFetch( queryGroup, group );
 
 			trackSelectionsForGroup = false;
@@ -1997,6 +1999,10 @@ public QueryGroup visitQueryGroup(SqmQueryGroup<?> queryGroup) {
 				newQueryParts.add( visitQueryPart( queryParts.get( i ) ) );
 			}
 
+			// Register the table groups from the first sub-queryspec's FromClauseIndex
+			// as they might be needed to resolve the tuple type's table groups
+			firstQueryPartIndex.copyInto( fromClauseIndexStack.getCurrent() );
+
 			return group;
 		}
 		finally {

hibernate-core/src/main/java/org/hibernate/query/sqm/sql/FromClauseIndex.java

@@ -7,6 +7,7 @@
 import java.util.HashMap;
 import java.util.Map;
 
+import org.hibernate.Internal;
 import org.hibernate.spi.NavigablePath;
 import org.hibernate.query.sqm.tree.domain.SqmPath;
 import org.hibernate.query.sqm.tree.from.SqmAttributeJoin;
@@ -89,4 +90,9 @@ public boolean isResolved(SqmFrom fromElement) {
 	public SqmAttributeJoin findFetchedJoinByPath(NavigablePath path) {
 		return fetchesByPath == null ? null : fetchesByPath.get( path.getIdentifierForTableGroup() );
 	}
+
+	@Internal
+	public void copyInto(FromClauseIndex index) {
+		index.tableGroupMap.putAll( tableGroupMap );
+	}
 }