support for selecting of joined plural attributes

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

@@ -41,6 +41,7 @@ import org.hibernate.grammars.hql.HqlParser;
 import org.hibernate.grammars.hql.HqlParserBaseVisitor;
 import org.hibernate.internal.util.collections.Stack;
 import org.hibernate.internal.util.collections.StandardStack;
+import org.hibernate.jpa.spi.JpaCompliance;
 import org.hibernate.metamodel.CollectionClassification;
 import org.hibernate.metamodel.model.domain.AllowableFunctionReturnType;
 import org.hibernate.metamodel.model.domain.BasicDomainType;
@@ -825,7 +826,29 @@ public class SemanticQueryBuilder<R> extends HqlParserBaseVisitor<Object> implem
 		}
 
 		if ( ctx.selectExpression().expression() != null ) {
-			return (SqmExpression) ctx.selectExpression().expression().accept( this );
+			final SqmExpression<?> sqmExpression = (SqmExpression<?>) ctx.selectExpression().expression().accept( this );
+			if ( sqmExpression instanceof SqmPath ) {
+				final SqmPath<?> sqmPath = (SqmPath<?>) sqmExpression;
+				if ( sqmPath.getReferencedPathSource() instanceof PluralPersistentAttribute ) {
+					// for plural-attribute selections, use the element path as the selection
+					//		- this is not strictly JPA compliant
+					if ( creationOptions.useStrictJpaCompliance() ) {
+						SqmTreeCreationLogger.LOGGER.debugf(
+								"Raw selection of plural attribute not supported by JPA: %s.  Use `value(%s)` or `key(%s)` to indicate what part of the collection to select",
+								sqmPath.getAlias(),
+								sqmPath.getAlias(),
+								sqmPath.getAlias()
+						);
+					}
+
+					final PluralPersistentAttribute<?,?,?> pluralAttribute = (PluralPersistentAttribute<?,?,?>) sqmPath.getReferencedPathSource();
+					final SqmPath<?> elementPath = pluralAttribute.getElementPathSource().createSqmPath( sqmPath );
+					processingStateStack.getCurrent().getPathRegistry().register( elementPath );
+					return elementPath;
+				}
+			}
+
+			return sqmExpression;
 		}
 
 		throw new ParsingException( "Unexpected selection rule type : " + ctx.getText() );

hibernate-core/src/main/java/org/hibernate/sql/ast/tree/predicate/Predicate.java

@@ -6,11 +6,21 @@
  */
 package org.hibernate.sql.ast.tree.predicate;
 
+import org.hibernate.sql.ast.spi.SqlAstTreeHelper;
 import org.hibernate.sql.ast.tree.SqlAstNode;
 
 /**
+ * Models a predicate in the SQL AST
+ *
  * @author Steve Ebersole
  */
 public interface Predicate extends SqlAstNode {
+	/**
+	 * Short-cut for {@link SqlAstTreeHelper#combinePredicates}
+	 */
+	static Predicate combinePredicates(Predicate p1, Predicate p2) {
+		return SqlAstTreeHelper.combinePredicates( p1, p2 );
+	}
+
 	boolean isEmpty();
 }

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

@@ -214,6 +214,25 @@ public class SelectClauseTests extends BaseSqmUnitTest {
 
 	}
 
+	@Test
+	public void testPluralJoinSelection() {
+		collectionValueFunctionAssertions(
+				interpretSelect( "select l from EntityOfLists e join e.listOfBasics l" ),
+				EntityOfLists.class.getName() + ".listOfBasics",
+				"l"
+		);
+		collectionValueFunctionAssertions(
+				interpretSelect( "select l from EntityOfLists e join e.listOfComponents l" ),
+				EntityOfLists.class.getName() + ".listOfComponents",
+				"l"
+		);
+		collectionValueFunctionAssertions(
+				interpretSelect( "select l from EntityOfLists e join e.listOfOneToMany l" ),
+				EntityOfLists.class.getName() + ".listOfOneToMany",
+				"l"
+		);
+	}
+
 	@Test
 	public void testCollectionValueFunction() {
 		collectionValueFunctionAssertions(