HHH-17666 Fix trunc function argument type resolver

hibernate-core/src/main/java/org/hibernate/dialect/function/TruncFunction.java

@@ -72,7 +72,10 @@ public class TruncFunction extends AbstractSqmFunctionDescriptor {
 				"trunc",
 				new TruncArgumentsValidator(),
 				StandardFunctionReturnTypeResolvers.useArgType( 1 ),
-				StandardFunctionArgumentTypeResolvers.ARGUMENT_OR_IMPLIED_RESULT_TYPE
+				StandardFunctionArgumentTypeResolvers.byArgument(
+						StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE,
+						StandardFunctionArgumentTypeResolvers.NULL
+				)
 		);
 		this.numericRenderingSupport = new TruncRenderingSupport(
 				new PatternRenderer( truncPattern ),

hibernate-core/src/test/java/org/hibernate/orm/test/query/hql/TruncConvertedDatetimeAttributeTest.java

@@ -0,0 +1,128 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later
+ * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
+ */
+package org.hibernate.orm.test.query.hql;
+
+import java.sql.Timestamp;
+import java.time.Instant;
+import java.time.ZoneOffset;
+import java.time.ZonedDateTime;
+import java.time.temporal.ChronoUnit;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.GregorianCalendar;
+
+import org.hibernate.dialect.DerbyDialect;
+
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.Jira;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.hibernate.testing.orm.junit.SkipForDialect;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.AttributeConverter;
+import jakarta.persistence.Convert;
+import jakarta.persistence.Converter;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Marco Belladelli
+ */
+@DomainModel( annotatedClasses = TruncConvertedDatetimeAttributeTest.TestEntity.class )
+@SessionFactory
+@SkipForDialect( dialectClass = DerbyDialect.class, reason = "Derby doesn't support any form of date truncation" )
+@Jira( "https://hibernate.atlassian.net/browse/HHH-17666" )
+public class TruncConvertedDatetimeAttributeTest {
+	private static final Date DATE = new GregorianCalendar( 2017, Calendar.JANUARY, 24 ).getTime();
+	private static final Instant INSTANT = ZonedDateTime.of( 2020, 10, 15, 20, 34, 45, 0, ZoneOffset.UTC ).toInstant();
+
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction( session -> session.persist( new TestEntity( 1L, DATE.getTime(), INSTANT ) ) );
+	}
+
+	@AfterAll
+	public void tearDown(SessionFactoryScope scope) {
+		scope.inTransaction( session -> session.createMutationQuery( "delete from TestEntity" ).executeUpdate() );
+	}
+
+	@Test
+	public void testTruncSelection(SessionFactoryScope scope) {
+		scope.inSession( session -> {
+			assertThat( session.createQuery(
+					"select trunc(instantCol, minute) from TestEntity",
+					Instant.class
+			).getSingleResult() ).isEqualTo( INSTANT.truncatedTo( ChronoUnit.MINUTES ) );
+			assertThat( session.createQuery(
+					"select trunc(dateCol, month) from TestEntity",
+					Long.class
+			).getSingleResult() ).isEqualTo( new GregorianCalendar( 2017, Calendar.JANUARY, 1 ).getTime().getTime() );
+		} );
+	}
+
+	@Test
+	public void testTruncComparison(SessionFactoryScope scope) {
+		scope.inSession( session -> {
+			assertThat( session.createQuery(
+					"from TestEntity where trunc(instantCol, hour) < current_date",
+					TestEntity.class
+			).getResultList() ).hasSize( 1 );
+			assertThat( session.createQuery(
+					"from TestEntity where trunc(dateCol, year) < current_timestamp",
+					TestEntity.class
+			).getResultList() ).hasSize( 1 );
+		} );
+	}
+
+	@Entity( name = "TestEntity" )
+	public static class TestEntity {
+		@Id
+		private Long id;
+
+		@Convert( converter = DateConverter.class )
+		private Long dateCol;
+
+		@Convert( converter = InstantConverter.class )
+		private Instant instantCol;
+
+		public TestEntity() {
+		}
+
+		public TestEntity(Long id, Long dateCol, Instant instantCol) {
+			this.id = id;
+			this.dateCol = dateCol;
+			this.instantCol = instantCol;
+		}
+	}
+
+	@Converter
+	public static class DateConverter implements AttributeConverter<Long, Date> {
+		public Date convertToDatabaseColumn(Long time) {
+			return time == null ? null : new Date( time );
+		}
+
+		public Long convertToEntityAttribute(Date date) {
+			return date == null ? null : date.getTime();
+		}
+	}
+
+	@Converter
+	public static class InstantConverter implements AttributeConverter<Instant, Timestamp> {
+		public Timestamp convertToDatabaseColumn(Instant instant) {
+			return instant == null ? null : Timestamp.from( instant );
+		}
+
+		public Instant convertToEntityAttribute(Timestamp timestamp) {
+			return timestamp == null ? null : timestamp.toInstant();
+		}
+	}
+}