qmllint: Support "length" property of sequence types

In particular, you can set and get the length of QQmlListProperty.

Change-Id: I5c8e03a752aad9bf9789faf85a0c3e280f0cbb4b
Reviewed-by: Maximilian Goldstein <max.goldstein@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>

src/qmlcompiler/qqmljstyperesolver.cpp

@@ -90,7 +90,7 @@ QQmlJSTypeResolver::QQmlJSTypeResolver(QQmlJSImporter *importer, const QmlIR::Do
     QQmlJSScope::Ptr listPropertyType = QQmlJSScope::create();
     listPropertyType->setInternalName(u"QQmlListProperty<QObject>"_qs);
     listPropertyType->setFileName(u"qqmllist.h"_qs);
-    listPropertyType->setAccessSemantics(QQmlJSScope::AccessSemantics::Value);
+    listPropertyType->setAccessSemantics(QQmlJSScope::AccessSemantics::Sequence);
     m_listPropertyType = listPropertyType;
 
     // This is pre-sorted. Don't mess it up.
@@ -754,6 +754,17 @@ bool QQmlJSTypeResolver::checkEnums(const QQmlJSScope::ConstPtr &scope, const QS
     return false;
 }
 
+QQmlJSRegisterContent QQmlJSTypeResolver::lengthProperty(
+        bool isWritable, const QQmlJSScope::ConstPtr &scope) const
+{
+    QQmlJSMetaProperty prop;
+    prop.setPropertyName(u"length"_qs);
+    prop.setTypeName(u"int"_qs);
+    prop.setType(intType());
+    prop.setIsWritable(isWritable);
+    return QQmlJSRegisterContent::create(intType(), prop, QQmlJSRegisterContent::Builtin, scope);
+}
+
 QQmlJSRegisterContent QQmlJSTypeResolver::memberType(const QQmlJSScope::ConstPtr &type,
                                                      const QString &name) const
 {
@@ -769,13 +780,9 @@ QQmlJSRegisterContent QQmlJSTypeResolver::memberType(const QQmlJSScope::ConstPtr
                                              QQmlJSRegisterContent::JavaScriptObjectProperty, type);
     }
 
-    if (type == stringType() && name == u"length"_qs) {
-        QQmlJSMetaProperty prop;
-        prop.setPropertyName(name);
-        prop.setTypeName(u"int"_qs);
-        prop.setType(intType());
-        prop.setIsWritable(false);
-        return QQmlJSRegisterContent::create(intType(), prop, QQmlJSRegisterContent::Builtin, type);
+    if ((type == stringType() || type->accessSemantics() == QQmlJSScope::AccessSemantics::Sequence)
+            && name == u"length"_qs) {
+        return lengthProperty(type != stringType(), type);
     }
 
     const auto check = [&](const QQmlJSScope::ConstPtr &scope, BaseOrExtension mode) {
@@ -859,8 +866,8 @@ QQmlJSRegisterContent QQmlJSTypeResolver::memberType(const QQmlJSRegisterContent
     }
     if (type.isProperty()) {
         const auto prop = type.property();
-        if (prop.isList())
-            return {};
+        if (prop.isList() && name == u"length"_qs)
+            return lengthProperty(true, listPropertyType());
         return memberType(prop.type(), name);
     }
     if (type.isEnumeration()) {

src/qmlcompiler/qqmljstyperesolver_p.h

@@ -158,6 +158,7 @@ protected:
     bool isNumeric(const QQmlJSScope::ConstPtr &type) const;
     bool checkEnums(const QQmlJSScope::ConstPtr &scope, const QString &name,
                     QQmlJSRegisterContent *result, BaseOrExtension mode) const;
+    QQmlJSRegisterContent lengthProperty(bool isWritable, const QQmlJSScope::ConstPtr &scope) const;
 
     QQmlJSScope::ConstPtr m_voidType;
     QQmlJSScope::ConstPtr m_numberType;

tests/auto/qml/qmllint/data/listIndices.qml

@@ -0,0 +1,14 @@
+pragma Strict
+import QtQml
+
+QtObject {
+    id: self
+    property list<QtObject> items
+    property int numItems: items.length
+
+    Component.onCompleted: {
+        items.length = 3
+        for (var i = 0; i < 3; ++i)
+            items[i] = self
+    }
+}

tests/auto/qml/qmllint/tst_qmllint.cpp

@@ -71,6 +71,7 @@ private Q_SLOTS:
     void settingsFile();
 
     void additionalImplicitImport();
+    void listIndices();
 
 private:
     QString runQmllint(const QString &fileToLint, std::function<void(QProcess &)> handleResult,
@@ -950,5 +951,10 @@ void TestQmllint::additionalImplicitImport()
             .isEmpty());
 }
 
+void TestQmllint::listIndices()
+{
+    QVERIFY(runQmllint("listIndices.qml", true, {"--compiler=warning"}, false).isEmpty());
+}
+
 QTEST_MAIN(TestQmllint)
 #include "tst_qmllint.moc"