HHH-19240 Simplify queryExpression grammar rule

Author: beikov

hibernate-core/src/main/antlr/org/hibernate/grammars/hql/HqlParser.g4

@@ -151,8 +151,7 @@ cycleClause
  * A toplevel query of subquery, which may be a union or intersection of subqueries
  */
 queryExpression
-	: withClause? orderedQuery								# SimpleQueryGroup
-	| withClause? orderedQuery (setOperator orderedQuery)+	# SetQueryGroup
+	: withClause? orderedQuery (setOperator orderedQuery)*
 	;
 
 /**

hibernate-core/src/main/java/org/hibernate/query/hql/internal/SemanticQueryBuilder.java

@@ -755,12 +755,10 @@ public Object visitCte(HqlParser.CteContext ctx) {
 		final var oldCte = currentPotentialRecursiveCte;
 		try {
 			currentPotentialRecursiveCte = null;
-			if ( queryExpressionContext instanceof HqlParser.SetQueryGroupContext setContext ) {
-				// A recursive query is only possible if the child count is lower than 5 e.g. `withClause? q1 op q2`
-				if ( setContext.getChildCount() < 5 ) {
-					if ( handleRecursive( ctx, setContext, cteContainer, name, cte, materialization ) ) {
-						return null;
-					}
+			// A recursive query is only possible if there are 2 ordered queries e.g. `q1 op q2`
+			if ( queryExpressionContext.orderedQuery().size() == 2 ) {
+				if ( handleRecursive( ctx, queryExpressionContext, cteContainer, name, cte, materialization ) ) {
+					return null;
 				}
 			}
 			queryExpressionContext.accept( this );
@@ -778,7 +776,7 @@ public Object visitCte(HqlParser.CteContext ctx) {
 
 	private boolean handleRecursive(
 			HqlParser.CteContext cteContext,
-			HqlParser.SetQueryGroupContext setContext,
+			HqlParser.QueryExpressionContext setContext,
 			SqmCteContainer cteContainer,
 			String name,
 			SqmSelectQuery<Object> cte,
@@ -941,15 +939,6 @@ private static CteSearchClauseKind getCteSearchClauseKind(HqlParser.SearchClause
 		return ctx.BREADTH() != null ? CteSearchClauseKind.BREADTH_FIRST : CteSearchClauseKind.DEPTH_FIRST;
 	}
 
-	@Override
-	public SqmQueryPart<?> visitSimpleQueryGroup(HqlParser.SimpleQueryGroupContext ctx) {
-		final var withClauseContext = ctx.withClause();
-		if ( withClauseContext != null ) {
-			withClauseContext.accept( this );
-		}
-		return (SqmQueryPart<?>) ctx.orderedQuery().accept( this );
-	}
-
 	@Override
 	public SqmQueryPart<?> visitQueryOrderExpression(HqlParser.QueryOrderExpressionContext ctx) {
 		final var sqmQuerySpec = currentQuerySpec();
@@ -986,24 +975,27 @@ public SqmQueryPart<?> visitNestedQueryExpression(HqlParser.NestedQueryExpressio
 	}
 
 	@Override
-	public SqmQueryGroup<?> visitSetQueryGroup(HqlParser.SetQueryGroupContext ctx) {
+	public SqmQueryPart<?> visitQueryExpression(HqlParser.QueryExpressionContext ctx) {
 		var withClauseContext = ctx.withClause();
 		if ( withClauseContext != null ) {
 			withClauseContext.accept( this );
 		}
-		final var firstQueryPart = (SqmQueryPart<?>) ctx.orderedQuery(0).accept( this );
+		final var orderedQueryContexts = ctx.orderedQuery();
+		final var firstQueryPart = (SqmQueryPart<?>) orderedQueryContexts.get( 0 ).accept( this );
+		if ( orderedQueryContexts.size() == 1 ) {
+			return firstQueryPart;
+		}
 		SqmQueryGroup<?> queryGroup =
 				firstQueryPart instanceof SqmQueryGroup<?> sqmQueryGroup
 						? sqmQueryGroup
 						: new SqmQueryGroup<>( firstQueryPart );
 		setCurrentQueryPart( queryGroup );
-		final var orderedQueryContexts = ctx.orderedQuery();
 		final var setOperatorContexts = ctx.setOperator();
 		final var firstProcessingState = processingStateStack.pop();
 		for ( int i = 0; i < setOperatorContexts.size(); i++ ) {
 			queryGroup = getSqmQueryGroup(
 					visitSetOperator( setOperatorContexts.get(i) ),
-					orderedQueryContexts.get( i+1 ),
+					orderedQueryContexts.get( i + 1 ),
 					queryGroup,
 					setOperatorContexts.size(),
 					firstProcessingState,