initial working literal and parameter selection

hibernate-core/src/main/java/org/hibernate/query/sqm/internal/QuerySqmImpl.java

@@ -44,11 +44,13 @@ import org.hibernate.query.spi.QueryParameterBindings;
 import org.hibernate.query.spi.QueryParameterImplementor;
 import org.hibernate.query.spi.ScrollableResultsImplementor;
 import org.hibernate.query.spi.SelectQueryPlan;
+import org.hibernate.query.sqm.SqmExpressable;
 import org.hibernate.query.sqm.mutation.spi.DeleteHandler;
 import org.hibernate.query.sqm.mutation.spi.UpdateHandler;
 import org.hibernate.query.sqm.tree.SqmDmlStatement;
 import org.hibernate.query.sqm.tree.SqmStatement;
 import org.hibernate.query.sqm.tree.delete.SqmDeleteStatement;
+import org.hibernate.query.sqm.tree.expression.SqmParameter;
 import org.hibernate.query.sqm.tree.select.SqmSelectStatement;
 import org.hibernate.query.sqm.tree.select.SqmSelection;
 import org.hibernate.query.sqm.tree.update.SqmUpdateStatement;
@@ -199,11 +201,32 @@ public class QuerySqmImpl<R>
 
 			final SqmSelection sqmSelection = selections.get( 0 );
 
-			if ( ! resultClass.isAssignableFrom( sqmSelection.getNodeType().getExpressableJavaTypeDescriptor().getJavaType() ) ) {
+			if ( sqmSelection.getSelectableNode() instanceof SqmParameter ) {
+				final SqmParameter sqmParameter = (SqmParameter) sqmSelection.getSelectableNode();
+
+				// we may not yet know a selection type
+				if ( sqmParameter.getNodeType() == null || sqmParameter.getNodeType().getExpressableJavaTypeDescriptor() == null ) {
+					// we can't verify the result type up front
+					return;
+				}
+			}
+
+			verifyResultType( resultClass, sqmSelection.getNodeType(), sessionFactory );
+		}
+	}
+
+	private static <T> void verifyResultType(
+			Class<T> resultClass,
+			SqmExpressable<?> sqmExpressable,
+			SessionFactoryImplementor sessionFactory) {
+		assert sqmExpressable != null;
+		assert sqmExpressable.getExpressableJavaTypeDescriptor() != null;
+
+		if ( ! resultClass.isAssignableFrom( sqmExpressable.getExpressableJavaTypeDescriptor().getJavaType() ) ) {
 			final String errorMessage = String.format(
 					"Specified result type [%s] did not match Query selection type [%s] - multiple selections: use Tuple or array",
 					resultClass.getName(),
-						sqmSelection.getNodeType().getExpressableJavaTypeDescriptor().getJavaType().getName()
+					sqmExpressable.getExpressableJavaTypeDescriptor().getJavaType().getName()
 			);
 
 			if ( sessionFactory.getSessionFactoryOptions().getJpaCompliance().isJpaQueryComplianceEnabled() ) {
@@ -214,7 +237,6 @@ public class QuerySqmImpl<R>
 			}
 		}
 	}
-	}
 
 	@Override
 	public SessionFactoryImplementor getSessionFactory() {

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

@@ -220,6 +220,16 @@ public abstract class BaseSqmToSqlAstConverter
 		return sqlAliasBaseManager;
 	}
 
+	@Override
+	public DomainParameterXref getDomainParameterXref() {
+		return domainParameterXref;
+	}
+
+	@Override
+	public QueryParameterBindings getDomainParameterBindings() {
+		return domainParameterBindings;
+	}
+
 	@Override
 	public LockMode determineLockMode(String identificationVariable) {
 		return queryOptions.getLockOptions().getEffectiveLockMode( identificationVariable );
@@ -653,7 +663,17 @@ public abstract class BaseSqmToSqlAstConverter
 	}
 
 	protected MappingModelExpressable<?> determineValueMapping(SqmExpression<?> sqmExpression) {
-		final SqmExpressable<?> nodeType = sqmExpression.getNodeType();
+		SqmExpressable<?> nodeType = sqmExpression.getNodeType();
+
+		if ( nodeType == null ) {
+			if ( sqmExpression instanceof SqmParameter ) {
+				final SqmParameter sqmParameter = (SqmParameter) sqmExpression;
+				final QueryParameterBinding<?> binding = domainParameterBindings.getBinding( domainParameterXref.getQueryParameter( sqmParameter ) );
+				assert binding != null;
+
+				nodeType = binding.getBindType();
+			}
+		}
 
 		MappingModelExpressable valueMapping = getCreationContext().getDomainModel().resolveMappingExpressable( nodeType );
 

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

@@ -9,6 +9,8 @@ package org.hibernate.query.sqm.sql;
 import java.util.List;
 
 import org.hibernate.LockMode;
+import org.hibernate.query.spi.QueryParameterBindings;
+import org.hibernate.query.sqm.internal.DomainParameterXref;
 import org.hibernate.sql.ast.spi.FromClauseAccess;
 import org.hibernate.sql.ast.spi.SqlAliasBaseGenerator;
 import org.hibernate.sql.ast.spi.SqlAstCreationContext;
@@ -32,6 +34,10 @@ public interface SqlAstCreationState {
 
 	SqlAliasBaseGenerator getSqlAliasBaseGenerator();
 
+	DomainParameterXref getDomainParameterXref();
+
+	QueryParameterBindings getDomainParameterBindings();
+
 	LockMode determineLockMode(String identificationVariable);
 
 	/**

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

@@ -9,16 +9,24 @@ package org.hibernate.query.sqm.sql.internal;
 import java.util.List;
 
 import org.hibernate.metamodel.mapping.MappingModelExpressable;
+import org.hibernate.metamodel.model.domain.AllowableParameterType;
+import org.hibernate.query.SemanticException;
+import org.hibernate.query.spi.QueryParameterBinding;
+import org.hibernate.query.spi.QueryParameterImplementor;
 import org.hibernate.query.sqm.tree.expression.SqmParameter;
 import org.hibernate.sql.ast.spi.SqlAstWalker;
+import org.hibernate.sql.ast.spi.SqlSelection;
 import org.hibernate.sql.ast.tree.expression.Expression;
 import org.hibernate.sql.ast.tree.expression.SqlTuple;
 import org.hibernate.sql.exec.spi.JdbcParameter;
+import org.hibernate.sql.results.internal.domain.basic.BasicResult;
+import org.hibernate.sql.results.spi.DomainResult;
+import org.hibernate.sql.results.spi.DomainResultCreationState;
 
 /**
  * @author Steve Ebersole
  */
-public class SqmParameterInterpretation implements Expression {
+public class SqmParameterInterpretation implements Expression, DomainResultProducer {
 	private final SqmParameter sqmParameter;
 	private final MappingModelExpressable valueMapping;
 
@@ -48,4 +56,40 @@ public class SqmParameterInterpretation implements Expression {
 	public MappingModelExpressable getExpressionType() {
 		return valueMapping;
 	}
+
+	@Override
+	public DomainResult createDomainResult(
+			String resultVariable,
+			DomainResultCreationState creationState) {
+		if ( resolvedExpression instanceof SqlTuple ) {
+			throw new SemanticException( "Composite query parameter cannot be used in select" );
+		}
+
+		AllowableParameterType nodeType = sqmParameter.getNodeType();
+		if ( nodeType == null ) {
+			final QueryParameterImplementor<?> queryParameter = creationState.getSqlAstCreationState()
+					.getDomainParameterXref()
+					.getQueryParameter( sqmParameter );
+			final QueryParameterBinding<?> binding = creationState.getSqlAstCreationState()
+					.getDomainParameterBindings()
+					.getBinding( queryParameter );
+			nodeType = binding.getBindType();
+		}
+
+		final SqlSelection sqlSelection = creationState.getSqlAstCreationState().getSqlExpressionResolver().resolveSqlSelection(
+				resolvedExpression,
+				nodeType.getExpressableJavaTypeDescriptor(),
+				creationState.getSqlAstCreationState()
+						.getCreationContext()
+						.getSessionFactory()
+						.getTypeConfiguration()
+		);
+
+		//noinspection unchecked
+		return new BasicResult(
+				sqlSelection.getValuesArrayPosition(),
+				resultVariable,
+				nodeType.getExpressableJavaTypeDescriptor()
+		);
+	}
 }

hibernate-core/src/main/java/org/hibernate/sql/ast/tree/expression/AbstractLiteral.java

@@ -76,7 +76,7 @@ public abstract class AbstractLiteral<T>
 
 		//noinspection unchecked
 		return new BasicResult<>(
-				sqlSelection.getJdbcResultSetIndex(),
+				sqlSelection.getValuesArrayPosition(),
 				resultVariable,
 				type.getMappedTypeDescriptor().getMappedJavaTypeDescriptor()
 		);

hibernate-core/src/main/java/org/hibernate/sql/exec/internal/AbstractJdbcParameter.java

@@ -13,13 +13,16 @@ import java.util.function.Consumer;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
 import org.hibernate.metamodel.mapping.JdbcMapping;
 import org.hibernate.metamodel.mapping.MappingModelExpressable;
+import org.hibernate.metamodel.mapping.SqlExpressable;
 import org.hibernate.sql.ast.Clause;
+import org.hibernate.sql.ast.spi.SqlSelection;
 import org.hibernate.sql.exec.ExecutionException;
 import org.hibernate.sql.exec.spi.ExecutionContext;
 import org.hibernate.sql.exec.spi.JdbcParameter;
 import org.hibernate.sql.exec.spi.JdbcParameterBinder;
 import org.hibernate.sql.exec.spi.JdbcParameterBinding;
 import org.hibernate.sql.exec.spi.JdbcParameterBindings;
+import org.hibernate.sql.results.internal.SqlSelectionImpl;
 import org.hibernate.type.BasicType;
 import org.hibernate.type.descriptor.java.JavaTypeDescriptor;
 import org.hibernate.type.spi.TypeConfiguration;
@@ -28,7 +31,7 @@ import org.hibernate.type.spi.TypeConfiguration;
  * @author Steve Ebersole
  */
 public abstract class AbstractJdbcParameter
-		implements JdbcParameter, JdbcParameterBinder, MappingModelExpressable {
+		implements JdbcParameter, JdbcParameterBinder, MappingModelExpressable, SqlExpressable {
 
 	private final JdbcMapping jdbcMapping;
 
@@ -41,6 +44,29 @@ public abstract class AbstractJdbcParameter
 		return this;
 	}
 
+	@Override
+	public JdbcMapping getJdbcMapping() {
+		return jdbcMapping;
+	}
+
+	@Override
+	public SqlSelection createSqlSelection(
+			int jdbcPosition,
+			int valuesArrayPosition,
+			JavaTypeDescriptor javaTypeDescriptor,
+			TypeConfiguration typeConfiguration) {
+		// todo (6.0) : investigate "virtual" or "static" selections
+		//		- anything that is the same for each row always - parameter, literal, etc;
+		//			the idea would be to write the value directly into the JdbcValues array
+		//			and not generating a SQL selection in the query sent to DB
+		return new SqlSelectionImpl(
+				jdbcPosition,
+				valuesArrayPosition,
+				this,
+				jdbcMapping
+		);
+	}
+
 	@Override
 	public void bindParameterValue(
 			PreparedStatement statement,

hibernate-core/src/test/java/org/hibernate/orm/test/sql/exec/SmokeTests.java

@@ -160,6 +160,28 @@ public class SmokeTests {
 		);
 	}
 
+	@Test
+	public void testHqlSelectLiteral(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					final QueryImplementor<String> query = session.createQuery( "select 'items' from SimpleEntity e", String.class );
+					final String attribute1 = query.uniqueResult();
+					assertThat( attribute1, is( "items" ) );
+				}
+		);
+	}
+
+	@Test
+	public void testHqlSelectParameter(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					final QueryImplementor<String> query = session.createQuery( "select :param from SimpleEntity e", String.class );
+					final String attribute1 = query.setParameter( "param", "items" ).uniqueResult();
+					assertThat( attribute1, is( "items" ) );
+				}
+		);
+	}
+
 
 	// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 	// Dynamic instantiations
@@ -254,6 +276,26 @@ public class SmokeTests {
 		);
 	}
 
+	@Test
+	public void testHqlNestedDynamicInstantiationWithLiteral(SessionFactoryScope scope) {
+		scope.getSessionFactory().inTransaction(
+				session -> {
+					final Query<CategorizedListItemDto> query = session.createQuery(
+							"select new CategorizedListItemDto( new ListItemDto( 'items', e.component.attribute1 ), e.component.attribute2, e.name ) from SimpleEntity e",
+							CategorizedListItemDto.class
+					);
+
+					final CategorizedListItemDto dto = query.getSingleResult();
+					assertThat( dto, notNullValue() );
+					assertThat( dto.category, notNullValue() );
+					assertThat( dto.category.code, is( "items") );
+					assertThat( dto.category.value, is( "a1") );
+					assertThat( dto.code, is( "a2" ) );
+					assertThat( dto.value, is( "Fab" ) );
+				}
+		);
+	}
+
 	@Test
 	public void testHqlMultipleDynamicInstantiation(SessionFactoryScope scope) {
 		scope.getSessionFactory().inTransaction(
@@ -278,7 +320,7 @@ public class SmokeTests {
 	}
 
 	@Test
-	public void testBasicSetterDynamicInstantiation(SessionFactoryScope scope) {
+	public void testHqlBasicSetterDynamicInstantiation(SessionFactoryScope scope) {
 		scope.getSessionFactory().inTransaction(
 				session -> {
 					final Query<BasicSetterBasedDto> query = session.createQuery(