Fix QQmlProperty and Connections for properties starting with '_'

We do a weird renaming for the change handler of properties starting
with '_', now we do it at least in a consistent way.

Fixes: QTBUG-82017
Change-Id: I1535a5ee462f3a344c972461f1fb954f039aa854
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 9 insertions, 3 deletions

diff --git a/src/qml/qml/qqmlproperty.cpp b/src/qml/qml/qqmlproperty.cpp
index d191d07258..86cb606f83 100644
--- a/src/qml/qml/qqmlproperty.cpp
+++ b/src/qml/qml/qqmlproperty.cpp
@@ -353,10 +353,15 @@ void QQmlPropertyPrivate::initProperty(QObject *obj, const QString &name)
     if (terminal.count() >= 3 &&
         terminal.at(0) == QLatin1Char('o') &&
         terminal.at(1) == QLatin1Char('n') &&
-        terminal.at(2).isUpper()) {
+        (terminal.at(2).isUpper() || terminal.at(2) == '_')) {
 
         QString signalName = terminal.mid(2).toString();
-        signalName[0] = signalName.at(0).toLower();
+        int firstNon_;
+        int length = signalName.length();
+        for (firstNon_ = 0; firstNon_ < length; ++firstNon_)
+            if (signalName.at(firstNon_) != '_')
+                break;
+        signalName[firstNon_] = signalName.at(firstNon_).toLower();
 
         // XXX - this code treats methods as signals
 
diff --git a/src/qml/types/qqmlconnections.cpp b/src/qml/types/qqmlconnections.cpp
index 1e801641e5..4c44bba43e 100644
--- a/src/qml/types/qqmlconnections.cpp
+++ b/src/qml/types/qqmlconnections.cpp
@@ -238,7 +238,8 @@ void QQmlConnectionsParser::verifyBindings(const QQmlRefPointer<QV4::ExecutableC
         const QV4::CompiledData::Binding *binding = props.at(ii);
         const QString &propName = compilationUnit->stringAt(binding->propertyNameIndex);
 
-        if (!propName.startsWith(QLatin1String("on")) || (propName.length() < 3 || !propName.at(2).isUpper())) {
+        const bool thirdCharacterIsValid = (propName.length() >= 2) && (propName.at(2).isUpper() || propName.at(2) == '_');
+        if (!propName.startsWith(QLatin1String("on")) || !thirdCharacterIsValid) {
             error(props.at(ii), QQmlConnections::tr("Cannot assign to non-existent property \"%1\"").arg(propName));
             return;
         }