qmllint: Improve parent handling

- Do not warn about parent access in unknown components
  This avoids false positive warnings when an imported component could not
  be found (or when it actually was not imported).
  We still warn about the component which could not be found, so the user
  is still informed that something is not right.

  We also still emit a warning when we know the properties of a component,
  and parent is not one of them.
- Do not recommend the use of parent to address the root components
  properties. For this to work, we would need to know whether the root
  component reparents its children or not. Moreover, id lookups are
  actually faster than parent lookups.

Change-Id: I83d0e71e4bf20d34a3e6d836c2b123b2bf0d416e
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

4 files changed, 45 insertions, 18 deletions

diff --git a/tests/auto/qml/qmllint/data/FromRootDirectParent.qml b/tests/auto/qml/qmllint/data/FromRootDirectParent.qml
deleted file mode 100644
index c0bfd0f26b..0000000000
--- a/tests/auto/qml/qmllint/data/FromRootDirectParent.qml
+++ /dev/null
@@ -1,14 +0,0 @@
-import QtQuick 2.0
-
-Item {
-    id: root
-    property int unqualified: 42
-
-    Item {
-        x: unqualified // user defined property from root
-    }
-
-    QtObject {
-        property int check: x // existing property from root
-    }
-}
diff --git a/tests/auto/qml/qmllint/data/nonSpuriousParentWarning.qml b/tests/auto/qml/qmllint/data/nonSpuriousParentWarning.qml
new file mode 100644
index 0000000000..a59b736929
--- /dev/null
+++ b/tests/auto/qml/qmllint/data/nonSpuriousParentWarning.qml
@@ -0,0 +1,8 @@
+import QtQuick 2.12
+import QtQml 2.12
+
+Item {
+    QtObject {
+        property int x: parent.x
+    }
+}
diff --git a/tests/auto/qml/qmllint/data/spuriousParentWarning.qml b/tests/auto/qml/qmllint/data/spuriousParentWarning.qml
new file mode 100644
index 0000000000..1323593031
--- /dev/null
+++ b/tests/auto/qml/qmllint/data/spuriousParentWarning.qml
@@ -0,0 +1,7 @@
+import QtQuick 2.12
+
+Item {
+    Unknown {
+        property int x: parent.x
+    }
+}
diff --git a/tests/auto/qml/qmllint/main.cpp b/tests/auto/qml/qmllint/main.cpp
index 1069aa5a33..928575bc82 100644
--- a/tests/auto/qml/qmllint/main.cpp
+++ b/tests/auto/qml/qmllint/main.cpp
@@ -40,6 +40,7 @@ private Q_SLOTS:
     void test_data();
     void testUnqualified();
     void testUnqualified_data();
+    void testUnqualifiedNoSpuriousParentWarning();
 private:
     QString m_qmllintPath;
 };
@@ -73,13 +74,14 @@ void TestQmllint::test_data()
 
 void TestQmllint::testUnqualified()
 {
+    auto qmlImportDir = QLibraryInfo::location(QLibraryInfo::Qml2ImportsPath);
     QFETCH(QString, filename);
     QFETCH(QString, warningMessage);
     QFETCH(int, warningLine);
     QFETCH(int, warningColumn);
     filename.prepend(QStringLiteral("data/"));
     QStringList args;
-    args << QStringLiteral("-U") << filename;
+    args << QStringLiteral("-U") << filename  << QStringLiteral("-I") << qmlImportDir;
 
     QProcess process;
     process.start(m_qmllintPath, args);
@@ -106,9 +108,6 @@ void TestQmllint::testUnqualified_data()
     // access property of root object
     QTest::newRow("FromRootDirect") << QStringLiteral("FromRoot.qml") << QStringLiteral("x: root.unqualified") << 9 << 16; // new property
     QTest::newRow("FromRootAccess") << QStringLiteral("FromRoot.qml") << QStringLiteral("property int check: root.x") << 13 << 33;  // builtin property
-    // access property of root object from direct child
-    QTest::newRow("FromRootDirectParentDirect") << QStringLiteral("FromRootDirectParent.qml") << QStringLiteral("x: parent.unqualified") << 8 << 12;
-    QTest::newRow("FromRootDirectParentAccess") << QStringLiteral("FromRootDirectParent.qml") << QStringLiteral("property int check: parent.x") << 12 << 29;
     // access injected name from signal
     QTest::newRow("SignalHandler1") << QStringLiteral("SignalHandler.qml") << QStringLiteral("onDoubleClicked:  function(mouse) {...") << 5 << 21;
     QTest::newRow("SignalHandler2") << QStringLiteral("SignalHandler.qml") << QStringLiteral("onPositionChanged:  function(mouse) {...") << 10 << 21;
@@ -117,6 +116,33 @@ void TestQmllint::testUnqualified_data()
 
 }
 
+void TestQmllint::testUnqualifiedNoSpuriousParentWarning()
+{
+    auto qmlImportDir = QLibraryInfo::location(QLibraryInfo::Qml2ImportsPath);
+    {
+        QString filename = QLatin1String("spuriousParentWarning.qml");
+        filename.prepend(QStringLiteral("data/"));
+        QStringList args;
+        args << QStringLiteral("-U") << filename << QStringLiteral("-I") << qmlImportDir;
+        QProcess process;
+        process.start(m_qmllintPath, args);
+        QVERIFY(process.waitForFinished());
+        QVERIFY(process.exitStatus() == QProcess::NormalExit);
+        QVERIFY(process.exitCode() == 0);
+    }
+    {
+        QString filename = QLatin1String("nonSpuriousParentWarning.qml");
+        filename.prepend(QStringLiteral("data/"));
+        QStringList args;
+        args << QStringLiteral("-U") << filename << QStringLiteral("-I") << qmlImportDir;
+        QProcess process;
+        process.start(m_qmllintPath, args);
+        QVERIFY(process.waitForFinished());
+        QVERIFY(process.exitStatus() == QProcess::NormalExit);
+        QVERIFY(process.exitCode());
+    }
+}
+
 void TestQmllint::test()
 {
     QFETCH(QString, filename);