Allow AOT functions to signal an undefined result via the context

undefined as value returned from bindings has the special meaning of
resetting the binding. As AOT-compiled functions return the actual type
of the binding rather than a QV4::Value, we cannot always encode
undefined. Therefore, add a flag that tells us whether the result was
supposed to be undefined.

Pick-to: 6.2
Change-Id: Iac2298869dde80f6d889240dd8200b2ad83e5dc5
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/qml/jsruntime/qv4stackframe_p.h b/src/qml/jsruntime/qv4stackframe_p.h
index 1439e9f677..9a121b48cd 100644
--- a/src/qml/jsruntime/qv4stackframe_p.h
+++ b/src/qml/jsruntime/qv4stackframe_p.h
@@ -90,6 +90,7 @@ struct Q_QML_PRIVATE_EXPORT CppStackFrameBase
             QObject *thisObject;
             const QMetaType *metaTypes;
             void **returnAndArgs;
+            bool returnValueIsUndefined;
         };
     };
 
@@ -163,11 +164,15 @@ struct Q_QML_PRIVATE_EXPORT MetaTypesStackFrame : public CppStackFrame
         CppStackFrameBase::context = context;
         CppStackFrameBase::metaTypes = metaTypes;
         CppStackFrameBase::returnAndArgs = returnAndArgs;
+        CppStackFrameBase::returnValueIsUndefined = false;
     }
 
     QMetaType returnType() const { return metaTypes[0]; }
     void *returnValue() const { return returnAndArgs[0]; }
 
+    bool isReturnValueUndefined() const { return CppStackFrameBase::returnValueIsUndefined; }
+    void setReturnValueUndefined() { CppStackFrameBase::returnValueIsUndefined = true; }
+
     const QMetaType *argTypes() const { return metaTypes + 1; }
     void **argv() const { return returnAndArgs + 1; }