HHH-19719 org.hibernate.query.sqm.function.SelfRenderingSqmWindowFunction#appendHqlString throws IndexOutOfBoundsException when has no arguments

hibernate-core/src/main/java/org/hibernate/query/sqm/function/SelfRenderingSqmWindowFunction.java

@@ -121,7 +121,7 @@ public void appendHqlString(StringBuilder hql, SqmRenderContext context) {
 		hql.append( getFunctionName() );
 		hql.append( '(' );
 		int i = 1;
-		if ( arguments.get( 0 ) instanceof SqmDistinct<?> ) {
+		if ( !arguments.isEmpty() && arguments.get( 0 ) instanceof SqmDistinct<?> ) {
 			arguments.get( 0 ).appendHqlString( hql, context );
 			if ( arguments.size() > 1 ) {
 				hql.append( ' ' );

hibernate-core/src/test/java/org/hibernate/orm/test/query/sqm/SelfRenderingSqmFunctionWithoutArgumentsTest.java

@@ -0,0 +1,64 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.query.sqm;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import org.hibernate.testing.orm.junit.DialectFeatureChecks.SupportPartitionBy;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.RequiresDialectFeature;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+@DomainModel(
+		annotatedClasses = SelfRenderingSqmFunctionWithoutArgumentsTest.Dummy.class
+)
+@SessionFactory
+@JiraKey("HHH-19719")
+@RequiresDialectFeature(feature = SupportPartitionBy.class)
+public class SelfRenderingSqmFunctionWithoutArgumentsTest {
+
+	@BeforeAll
+	static void init(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			session.persist( new Dummy(1, "John Doe") );
+			session.persist( new Dummy(2, "Dave Default") );
+		} );
+	}
+
+	@Test
+	void test(SessionFactoryScope scope) {
+		scope.inSession( session -> {
+			session.createQuery( """
+					with tmp as (
+						select id id, name name, row_number() over (order by name) pos
+						from Dummy
+					)
+					select id, name, pos from tmp
+					""" ).getResultList();
+		} );
+
+	}
+
+	@Entity(name = "Dummy")
+	static class Dummy {
+		@Id
+		private Integer id;
+
+		private String name;
+
+		private Dummy() {
+			// for use by Hibernate
+		}
+
+		public Dummy(Integer id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+	}
+}