HHH-6655 trim function on DB2 is broken

hibernate-core/src/main/java/org/hibernate/dialect/DB2Dialect.java

@@ -159,7 +159,7 @@ public class DB2Dialect extends Dialect {
 
 		registerFunction( "substring", new StandardSQLFunction( "substr", StandardBasicTypes.STRING ) );
 		registerFunction( "bit_length", new SQLFunctionTemplate( StandardBasicTypes.INTEGER, "length(?1)*8" ) );
-		registerFunction( "trim", new AnsiTrimEmulationFunction() );
+		registerFunction( "trim", new SQLFunctionTemplate( StandardBasicTypes.STRING, "trim(?1 ?2 ?3 ?4)" ) );
 
 		registerFunction( "concat", new VarArgsSQLFunction( StandardBasicTypes.STRING, "", "||", "" ) );
 

hibernate-entitymanager/src/main/java/org/hibernate/jpa/criteria/expression/function/TrimFunction.java

@@ -37,6 +37,7 @@ import org.hibernate.jpa.criteria.expression.LiteralExpression;
  * Models the ANSI SQL <tt>TRIM</tt> function.
  *
  * @author Steve Ebersole
+ * @author Brett Meyer
  */
 public class TrimFunction
 		extends BasicFunctionExpression<String>
@@ -118,11 +119,22 @@ public class TrimFunction
 
 	@Override
 	public String render(RenderingContext renderingContext) {
+		String renderedTrimChar;
+		if ( trimCharacter.getClass().isAssignableFrom( 
+				LiteralExpression.class ) ) {
+			// If the character is a literal, treat it as one.  A few dialects
+			// do not support parameters as trim() arguments.
+			renderedTrimChar = ( ( LiteralExpression<Character> ) 
+					trimCharacter ).getLiteral().toString();
+		} else {
+			renderedTrimChar = ( (Renderable) trimCharacter ).render( 
+					renderingContext );
+		}
 		return new StringBuilder()
 				.append( "trim(" )
 				.append( trimspec.name() )
 				.append( ' ' )
-				.append( ( (Renderable) trimCharacter ).render( renderingContext ) )
+				.append( renderedTrimChar )
 				.append( " from " )
 				.append( ( (Renderable) trimSource ).render( renderingContext ) )
 				.append( ')' )

hibernate-entitymanager/src/test/java/org/hibernate/jpa/test/criteria/CriteriaCompilingTest.java

@@ -92,8 +92,6 @@ public class CriteriaCompilingTest extends BaseEntityManagerFunctionalTestCase {
 	}
 
     @Test
-    @RequiresDialect( DB2Dialect.class )
-    @FailureExpected( jiraKey = "HHH-6655" )
     public void testTrim() {
         final String expectedResult = "David R. Vincent";
         EntityManager em = getOrCreateEntityManager();