fix memory leak instantiating QgsExpression in actions

Author: brushtyler

src/core/qgsattributeaction.cpp

@@ -206,26 +206,26 @@ QString QgsAttributeAction::expandAction( QString action, QgsFeature &feat, cons
     index = pos + rx.matchedLength();
 
     QString to_replace = rx.cap( 1 ).trimmed();
-    QgsDebugMsg( "Found expression:" + to_replace );
+    QgsDebugMsg( "Found expression: " + to_replace );
 
     if ( substitutionMap && substitutionMap->contains( to_replace ) )
     {
       expr_action += action.mid( start, pos - start ) + substitutionMap->value( to_replace ).toString();
       continue;
     }
 
-    QgsExpression* exp = new QgsExpression( to_replace );
-    if ( exp->hasParserError() )
+    QgsExpression exp( to_replace );
+    if ( exp.hasParserError() )
     {
-      QgsDebugMsg( "Expression parser error:" + exp->parserErrorString() );
+      QgsDebugMsg( "Expression parser error: " + exp.parserErrorString() );
       expr_action += action.mid( start, index - start );
       continue;
     }
 
-    QVariant result = exp->evaluate( &feat, mLayer->pendingFields() );
-    if ( exp->hasEvalError() )
+    QVariant result = exp.evaluate( &feat, mLayer->pendingFields() );
+    if ( exp.hasEvalError() )
     {
-      QgsDebugMsg( "Expression parser eval error:" + exp->evalErrorString() );
+      QgsDebugMsg( "Expression parser eval error: " + exp.evalErrorString() );
       expr_action += action.mid( start, index - start );
       continue;
     }