From a4893077c6495746abfb09d20e2aeaa42c35feac Mon Sep 17 00:00:00 2001
From: Ulf Hermann <ulf.hermann@qt.io>
Date: Wed, 22 Sep 2021 14:48:58 +0200
Subject: [PATCH] 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      | 27 +++++++++++++--------
 src/qmlcompiler/qqmljstyperesolver_p.h      |  1 +
 tests/auto/qml/qmllint/data/listIndices.qml | 14 +++++++++++
 tests/auto/qml/qmllint/tst_qmllint.cpp      |  8 +++++-
 4 files changed, 39 insertions(+), 11 deletions(-)
 create mode 100644 tests/auto/qml/qmllint/data/listIndices.qml

diff --git a/src/qmlcompiler/qqmljstyperesolver.cpp b/src/qmlcompiler/qqmljstyperesolver.cpp
index 6ef0ec1a53..ebdf5071cc 100644
--- a/src/qmlcompiler/qqmljstyperesolver.cpp
+++ b/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()) {
diff --git a/src/qmlcompiler/qqmljstyperesolver_p.h b/src/qmlcompiler/qqmljstyperesolver_p.h
index 072afff314..1c9ce82d86 100644
--- a/src/qmlcompiler/qqmljstyperesolver_p.h
+++ b/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;
diff --git a/tests/auto/qml/qmllint/data/listIndices.qml b/tests/auto/qml/qmllint/data/listIndices.qml
new file mode 100644
index 0000000000..b5fda4ef0d
--- /dev/null
+++ b/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
+    }
+}
diff --git a/tests/auto/qml/qmllint/tst_qmllint.cpp b/tests/auto/qml/qmllint/tst_qmllint.cpp
index bd417940ce..7147fa8755 100644
--- a/tests/auto/qml/qmllint/tst_qmllint.cpp
+++ b/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,
@@ -947,7 +948,12 @@ void TestQmllint::additionalImplicitImport()
     QVERIFY(runQmllint("additionalImplicitImport.qml", true,
                        QStringList() << "--resource" << testFile("implicitImportResource.qrc"),
                        false)
-                    .isEmpty());
+            .isEmpty());
+}
+
+void TestQmllint::listIndices()
+{
+    QVERIFY(runQmllint("listIndices.qml", true, {"--compiler=warning"}, false).isEmpty());
 }
 
 QTEST_MAIN(TestQmllint)