Fixed crash when changing file member of custom class

NEWS.md

@@ -5,6 +5,7 @@
 * Scripting: Added API for editing tile layers using terrain sets (with a-morphous, #3758)
 * Scripting: Support erasing tiles in Tool.preview and TileMap.merge
 * Scripting: Added WangSet.effectiveTypeForColor
+* Fixed crash when changing file property of custom class (#3783)
 * Fixed object preview position with parallax factor on group layer (#3669)
 * Fixed hover highlight rendering with active parallax factor (#3669)
 * Fixed updating of object selection outlines when changing parallax factor (#3669)

src/libtiled/properties.h

@@ -60,6 +60,9 @@ class TILEDSHARED_EXPORT PropertyValue
 
     const PropertyType *type() const;
     QString typeName() const;
+
+    bool operator==(const PropertyValue &o) const
+    { return typeId == o.typeId && value == o.value; }
 };
 
 class TILEDSHARED_EXPORT FilePath
@@ -70,6 +73,9 @@ class TILEDSHARED_EXPORT FilePath
 public:
     QUrl url;
 
+    bool operator==(const FilePath &o) const
+    { return url == o.url; }
+
     static QString toString(const FilePath &path);
     static FilePath fromString(const QString &string);
 };
@@ -82,6 +88,9 @@ class TILEDSHARED_EXPORT ObjectRef
 public:
     int id;
 
+    bool operator==(const ObjectRef &o) const
+    { return id == o.id; }
+
     static int toInt(const ObjectRef &ref) { return ref.id; }
     static ObjectRef fromInt(int id) { return ObjectRef { id }; }
 };

src/tiled/propertytypeseditor.cpp

@@ -1133,13 +1133,18 @@ void PropertyTypesEditor::memberValueChanged(const QStringList &path, const QVar
     if (!classType)
         return;
 
-    auto &topLevelName = path.first();
-
     if (!setPropertyMemberValue(classType->members, path, value))
         return;
 
-    if (auto property = mPropertiesHelper->property(topLevelName))
-        property->setValue(mPropertiesHelper->toDisplayValue(classType->members.value(topLevelName)));
+    // When a nested property was changed, we need to update the value of the
+    // top-level property to match.
+    if (path.size() > 1) {
+        auto &topLevelName = path.first();
+        if (auto property = mPropertiesHelper->property(topLevelName)) {
+            QScopedValueRollback<bool> updatingDetails(mUpdatingDetails, true);
+            property->setValue(mPropertiesHelper->toDisplayValue(classType->members.value(topLevelName)));
+        }
+    }
 
     applyPropertyTypes();
 }