Introduce type based overload of Qt.createComponent

Add type based createComponent overloads based on
QQmlComponent::loadFromModule. They provide a way to instantiate a
component by its type, specified by  a URI and typename pair.
This enables creating Components for inline component types and C++ only
types.
Support for directly passing the type is deferred to a later commit, as
it needs some care to work together with the compiler.

As the string based overload matches a mistaken call to the URL based
createComponent with parent and mode swapped (due to anything being
convertible to string), we add a check to detect this specific error
case and give a helpful error message.

[ChangeLog][QtQml] Qt.createComponent now supports creating a Component
from its module and type name (passed as strings).

Task-number: QTBUG-97156
Fixes: QTBUG-26278
Change-Id: I89e7430fe02d52f57230bfa1b0bfbcbfd0ead4b7
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

2 files changed, 50 insertions, 2 deletions

diff --git a/tests/auto/qml/qqmlecmascript/data/componentCreationForType.qml b/tests/auto/qml/qqmlecmascript/data/componentCreationForType.qml
new file mode 100644
index 0000000000..66b06d4f5c
--- /dev/null
+++ b/tests/auto/qml/qqmlecmascript/data/componentCreationForType.qml
@@ -0,0 +1,48 @@
+import QtQml
+
+QtObject {
+    id: root
+    property int status: -1
+    Component.onCompleted: {
+        let comp
+        comp = Qt.createComponent("QtQml", "QtObject")
+        if (comp.status !== Component.Ready) {
+            root.status = 1
+            return
+        }
+
+        comp = Qt.createComponent("QtQml", "QtObject", root)
+        if (comp.status !== Component.Ready) {
+            root.status = 2
+            return
+        }
+
+        comp = Qt.createComponent("QtQml", "QtObject", Component.PreferSynchronous, root)
+        if (comp.status !== Component.Ready) {
+            root.status = 3
+            return
+        }
+
+
+        comp = Qt.createComponent("QtQml", "QtObject", Component.Asynchronous)
+        // C++ component will _always_ be ready, even if we request async loading
+        if (comp.status !== Component.Ready) {
+            root.status = 4
+            return
+        }
+
+        comp = Qt.createComponent("QtQml", "DoesNotExist")
+        if (comp.status !== Component.Error) {
+            root.status = 5
+            return
+        }
+
+        comp = Qt.createComponent("NoSuchModule", "QtObject")
+        if (comp.status !== Component.Error) {
+            root.status = 6
+            return
+        }
+
+        root.status = 0
+    }
+}
diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index 2922b02643..f591a87dcb 100644
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -1964,11 +1964,11 @@ void tst_qqmlecmascript::componentCreation_data()
         << "null";
     QTest::newRow("invalidSecondArg")
         << "invalidSecondArg"
-        << "" // We cannot catch this case as coercing a string to a number is valid in JavaScript
+        << ":40: TypeError: Invalid arguments; did you swap mode and parent"
         << "";
     QTest::newRow("invalidThirdArg")
         << "invalidThirdArg"
-        << ":45: TypeError: Passing incompatible arguments to C++ functions from JavaScript is not allowed."
+        << ":45: TypeError: Invalid arguments; did you swap mode and parent"
         << "";
     QTest::newRow("invalidMode")
         << "invalidMode"