Support usage of boolean expression in predicate context

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

@@ -406,6 +406,7 @@ predicate
 	| NOT predicate											# NegatedPredicate
 	| predicate AND predicate								# AndPredicate
 	| predicate OR predicate								# OrPredicate
+	| expression											# BooleanExpressionPredicate
 	;
 
 comparisonOperator

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

@@ -148,6 +148,7 @@ import org.hibernate.query.sqm.tree.insert.SqmInsertValuesStatement;
 import org.hibernate.query.sqm.tree.insert.SqmValues;
 import org.hibernate.query.sqm.tree.predicate.SqmAndPredicate;
 import org.hibernate.query.sqm.tree.predicate.SqmBetweenPredicate;
+import org.hibernate.query.sqm.tree.predicate.SqmBooleanExpressionPredicate;
 import org.hibernate.query.sqm.tree.predicate.SqmComparisonPredicate;
 import org.hibernate.query.sqm.tree.predicate.SqmEmptinessPredicate;
 import org.hibernate.query.sqm.tree.predicate.SqmExistsPredicate;
@@ -1896,6 +1897,15 @@ public class SemanticQueryBuilder<R> extends HqlParserBaseVisitor<Object> implem
 		return new SqmExistsPredicate( expression, creationContext.getNodeBuilder() );
 	}
 
+	@Override
+	public SqmPredicate visitBooleanExpressionPredicate(HqlParser.BooleanExpressionPredicateContext ctx) {
+		final SqmExpression expression = (SqmExpression) ctx.expression().accept( this );
+		if ( expression.getJavaType() != Boolean.class ) {
+			throw new SemanticException( "Non-boolean expression used in predicate context: " + ctx.getText() );
+		}
+		return new SqmBooleanExpressionPredicate( expression, creationContext.getNodeBuilder() );
+	}
+
 	@Override
 	@SuppressWarnings("unchecked")
 	public Object visitEntityTypeExpression(HqlParser.EntityTypeExpressionContext ctx) {

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

@@ -4586,14 +4586,18 @@ public abstract class BaseSqmToSqlAstConverter<T extends Statement> extends Base
 
 	@Override
 	public Object visitBooleanExpressionPredicate(SqmBooleanExpressionPredicate predicate) {
-		Object booleanExpression = predicate.getBooleanExpression().accept( this );
+		final Object booleanExpression = predicate.getBooleanExpression().accept( this );
 		if ( booleanExpression instanceof SelfRenderingExpression ) {
-			return new SelfRenderingPredicate( (SelfRenderingExpression) booleanExpression );
+			final Predicate sqlPredicate = new SelfRenderingPredicate( (SelfRenderingExpression) booleanExpression );
+			if ( predicate.isNegated() ) {
+				return new NegatedPredicate( sqlPredicate );
+			}
+			return sqlPredicate;
 		}
 		else {
 			return new ComparisonPredicate(
 					(Expression) booleanExpression,
-					ComparisonOperator.EQUAL,
+					predicate.isNegated() ? ComparisonOperator.NOT_EQUAL : ComparisonOperator.EQUAL,
 					new QueryLiteral<>( true, basicType( Boolean.class ) )
 			);
 		}

hibernate-core/src/test/java/org/hibernate/orm/test/exceptionhandling/QueryExceptionHandlingTest.java

@@ -54,7 +54,7 @@ public class QueryExceptionHandlingTest extends BaseExceptionHandlingTest {
 	public void testInvalidQuery() {
 		try {
 			TransactionUtil2.inSession( sessionFactory(), s -> {
-				s.createQuery( "from A where blahblahblah" ).list();
+				s.createQuery( "from A a where" ).list();
 			} );
 			fail( "should have thrown an exception" );
 		}