Convert null variant values to empty lists

... if their declared type is a list. This is a workaround for
QTBUG-51237.

Change-Id: Ie9e02f5fd125ce73b993e59af0e3dc2b47fe14c1
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

2 files changed, 14 insertions, 3 deletions

diff --git a/src/lib/corelib/language/evaluatorscriptclass.cpp b/src/lib/corelib/language/evaluatorscriptclass.cpp
index 8230d3990..aa07935dc 100644
--- a/src/lib/corelib/language/evaluatorscriptclass.cpp
+++ b/src/lib/corelib/language/evaluatorscriptclass.cpp
@@ -398,8 +398,14 @@ static QString overriddenSourceDirectory(const Item *item)
 }
 
 inline void convertToPropertyType(const Item *item, const PropertyDeclaration::Type t,
-        QScriptValue &v)
+        Value::Type valueType, QScriptValue &v)
 {
+    if (valueType == Value::VariantValueType && v.isUndefined()
+            && (t == PropertyDeclaration::StringList || t == PropertyDeclaration::PathList)) {
+        v = v.engine()->newArray(); // QTBUG-51237
+        return;
+    }
+
     if (v.isUndefined() || v.isError())
         return;
     switch (t) {
@@ -497,7 +503,7 @@ QScriptValue EvaluatorScriptClass::property(const QScriptValue &object, const QS
         converter.start();
 
         const PropertyDeclaration decl = data->item->propertyDeclaration(name.toString());
-        convertToPropertyType(data->item, decl.type(), result);
+        convertToPropertyType(data->item, decl.type(), value->type(), result);
     }
 
     if (debugProperties)
diff --git a/src/lib/corelib/language/projectresolver.cpp b/src/lib/corelib/language/projectresolver.cpp
index e712aff49..bfb2eb74c 100644
--- a/src/lib/corelib/language/projectresolver.cpp
+++ b/src/lib/corelib/language/projectresolver.cpp
@@ -1129,7 +1129,12 @@ QVariantMap ProjectResolver::evaluateProperties(Item *item, Item *propertiesCont
             if (result.contains(it.key()))
                 break;
             VariantValuePtr vvp = it.value().staticCast<VariantValue>();
-            result[it.key()] = vvp->value();
+            QVariant v = vvp->value();
+
+            if (v.isNull() && !item->propertyDeclaration(it.key()).isScalar()) // QTBUG-51237
+                v = QStringList();
+
+            result[it.key()] = v;
             break;
         }
         }