[new compiler] Initial support for group properties

This implements support for "font.pixelSize: 24" for example. The representation
in the compile data structure is so that font.pixelSize is short-hand for

font {
    pixelSize: 24
}

which means that inside the braces is a complete object initializer. For that
initializer we create a dedicated CompiledData::Object, which however has its
type name empty. When populating the outer instance then, the "font" property
is read as QQmlValueType (a QObject) and instead of creating a new QObject we
use that value type as instance to run the rest of the QML object initializer
(everything in braces).

Change-Id: Ic0a37ac77ab88f582546b9c09a3d06a07726420b
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/qml/compiler/qv4compileddata_p.h b/src/qml/compiler/qv4compileddata_p.h
index c98d53a1fa..9f8bd80f4d 100644
--- a/src/qml/compiler/qv4compileddata_p.h
+++ b/src/qml/compiler/qv4compileddata_p.h
@@ -315,6 +315,9 @@ struct Property
 
 struct Object
 {
+    // An empty inherited type name suggests that this object doesn't require to be instantiated
+    // by itself but is merely used for grouped properties. It can therefore only have bindings,
+    // so nProperties, nFunctions and nSignals must be zero.
     quint32 inheritedTypeNameIndex;
     quint32 idIndex;
     quint32 indexOfDefaultProperty;