Fix calling Qt.binding() on bound functions

Calling Qt.binding() on a bound function object is a valid use
case and used to work until Qt 5.8.

The problem was that we optimized the code in QQmlBinding and
QQmlJavascriptExpression to directly work on a QV4::Function,
so this wouldn't work anymore.

To fix this make sure recursive calls to Function.bind() are
unrolled (so that the BoundFunction's target is never a bound
function itself), then add the bound function as an optional
member to the QQmlBinding and use it's bound arguments if
present.

Task-number: QTBUG-61927
Change-Id: I472214ddd82fc2a1212efd9b769861fc43d2ddaf
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 1 insertions, 3 deletions

diff --git a/src/qml/qml/qqmljavascriptexpression_p.h b/src/qml/qml/qqmljavascriptexpression_p.h
index bff8866011..01af3b89ca 100644
--- a/src/qml/qml/qqmljavascriptexpression_p.h
+++ b/src/qml/qml/qqmljavascriptexpression_p.h
@@ -116,8 +116,7 @@ public:
     inline QObject *scopeObject() const;
     inline void setScopeObject(QObject *v);
 
-    QQmlSourceLocation sourceLocation() const;
-    void setSourceLocation(const QQmlSourceLocation &location);
+    virtual QQmlSourceLocation sourceLocation() const;
 
     bool isValid() const { return context() != nullptr; }
 
@@ -188,7 +187,6 @@ private:
     QV4::PersistentValue m_qmlScope;
     QQmlRefPointer<QV4::CompiledData::CompilationUnit> m_compilationUnit;
     QV4::Function *m_v4Function;
-    QQmlSourceLocation *m_sourceLocation; // used for Qt.binding() created functions
 };
 
 class QQmlPropertyCapture