Allow for private properties to be implemented using QProperty

Recently the moc learned that Q_PROPERTY(int x ...) can mean that "x" is
implemented as QProperty and then allows installing bindings, etc. -
this works by scanning the same class' members.

For our own use of QProperty, we need to place the QProperty member
itself into the d-pointer to be able to maintain the ability to add new
properties without breaking binary compatibility. That however means
that moc can't know that a certain property is backed by QProperty - we
don't scan the members of the private class.

As a workaround, this change enables the syntax where the property type
used in Q_PRIVATE_PROPERTY may be wrapped with QProperty<T>.

In addition this patch fixes the compilation of such declared properties
by ensuring the accessor prefix (t->$accessor) is applied also for the
QProperty related meta call variants.

Change-Id: I8fbdc49319048b57f4eb0b65b56daba0459e9598
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

3 files changed, 32 insertions, 5 deletions

diff --git a/src/tools/moc/generator.cpp b/src/tools/moc/generator.cpp
index c0e1dca748..acb7cdffe9 100644
--- a/src/tools/moc/generator.cpp
+++ b/src/tools/moc/generator.cpp
@@ -1504,8 +1504,12 @@ void Generator::generateStaticMetacall()
                 const PropertyDef &p = cdef->propertyList.at(propindex);
                 if (!p.isQProperty)
                     continue;
-                fprintf(out, "        case %d: observer->setSource(_t->%s); break;\n",
-                        propindex, p.name.constData());
+                QByteArray prefix = "_t->";
+                if (p.inPrivateClass.size()) {
+                    prefix += p.inPrivateClass + "->";
+                }
+                fprintf(out, "        case %d: observer->setSource(%s%s); break;\n",
+                        propindex, prefix.constData(), p.name.constData());
             }
             fprintf(out, "        default: break;\n");
             fprintf(out, "        }\n");
@@ -1521,8 +1525,12 @@ void Generator::generateStaticMetacall()
                 const PropertyDef &p = cdef->propertyList.at(propindex);
                 if (!p.isQProperty)
                     continue;
-                fprintf(out, "        case %d: _t->%s.setBinding(*reinterpret_cast<QPropertyBinding<%s> *>(_a[0])); break;\n",
-                        propindex, p.name.constData(), p.type.constData());
+                QByteArray prefix = "_t->";
+                if (p.inPrivateClass.size()) {
+                    prefix += p.inPrivateClass + "->";
+                }
+                fprintf(out, "        case %d: %s%s.setBinding(*reinterpret_cast<QPropertyBinding<%s> *>(_a[0])); break;\n",
+                        propindex, prefix.constData(), p.name.constData(), p.type.constData());
             }
             fprintf(out, "        default: break;\n");
             fprintf(out, "        }\n");
diff --git a/src/tools/moc/moc.cpp b/src/tools/moc/moc.cpp
index edef9d3f04..2444d0db90 100644
--- a/src/tools/moc/moc.cpp
+++ b/src/tools/moc/moc.cpp
@@ -1228,9 +1228,23 @@ void Moc::createPropertyDef(PropertyDef &propDef)
 {
     propDef.location = index;
 
+    const bool isPrivateProperty = !propDef.inPrivateClass.isEmpty();
+    bool typeWrappedInQProperty = false;
+    if (isPrivateProperty) {
+        const int rewind = index;
+        if (test(IDENTIFIER) && lexem() == "QProperty" && test(LANGLE)) {
+            typeWrappedInQProperty = true;
+            propDef.isQProperty = true;
+        } else {
+            index = rewind;
+        }
+    }
+
     QByteArray type = parseType().name;
     if (type.isEmpty())
         error();
+    if (typeWrappedInQProperty)
+        next(RANGLE);
     propDef.designable = propDef.scriptable = propDef.stored = "true";
     propDef.user = "false";
 
@@ -1806,7 +1820,7 @@ void Moc::checkProperties(ClassDef *cdef)
         definedProperties.insert(p.name);
 
         if (p.read.isEmpty() && p.member.isEmpty()) {
-            if (!cdef->qPropertyMembers.contains(p.name)) {
+            if (!cdef->qPropertyMembers.contains(p.name) && !p.isQProperty) {
                 const int rewind = index;
                 if (p.location >= 0)
                     index = p.location;
diff --git a/tests/auto/tools/moc/tst_moc.cpp b/tests/auto/tools/moc/tst_moc.cpp
index 08dae7f6ca..f3cc21f502 100644
--- a/tests/auto/tools/moc/tst_moc.cpp
+++ b/tests/auto/tools/moc/tst_moc.cpp
@@ -1542,6 +1542,7 @@ class PrivatePropertyTest : public QObject
     Q_PRIVATE_PROPERTY(PrivatePropertyTest::d, QString blub4 MEMBER mBlub NOTIFY blub4Changed)
     Q_PRIVATE_PROPERTY(PrivatePropertyTest::d, QString blub5 MEMBER mBlub NOTIFY blub5Changed)
     Q_PRIVATE_PROPERTY(PrivatePropertyTest::d, QString blub6 MEMBER mConst CONSTANT)
+    Q_PRIVATE_PROPERTY(PrivatePropertyTest::d, QProperty<int> x)
     class MyDPointer {
     public:
         MyDPointer() : mConst("const"), mBar(0), mPlop(0) {}
@@ -1555,6 +1556,7 @@ class PrivatePropertyTest : public QObject
         void setBlub(const QString &value) { mBlub = value; }
         QString mBlub;
         const QString mConst;
+        QProperty<int> x;
     private:
         int mBar;
         int mPlop;
@@ -1590,6 +1592,9 @@ void tst_Moc::qprivateproperties()
     test.setProperty("baz", 4);
     QCOMPARE(test.property("baz"), QVariant::fromValue(4));
 
+    test.setProperty("x", 100);
+    QCOMPARE(test.property("x"), QVariant::fromValue(100));
+    QVERIFY(test.metaObject()->property(test.metaObject()->indexOfProperty("x")).isQProperty());
 }
 
 void tst_Moc::warnOnPropertyWithoutREAD()