Avoid side effects when en exception has been thrown.

We don't want to check for exceptions after every single
line on our runtime methods. A better way to handle this
is to add the check in all methods that have direct side
effects (as e.g. writing to a property of the JS stack).

We also need to return whereever we throw an exception.
To simplify the code, ExecutionContext::throwXxx methods now
return a ReturnedValue (always undefined) for convenience.

Change-Id: Ide6c804f819c731a3f14c6c43121d08029c9fb90
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index b0ede6fa20..cf39d7df4f 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -81,8 +81,7 @@ static QBasicAtomicInt engineSerial = Q_BASIC_ATOMIC_INITIALIZER(1);
 
 static ReturnedValue throwTypeError(SimpleCallContext *ctx)
 {
-    ctx->throwTypeError();
-    return Encode::undefined();
+    return ctx->throwTypeError();
 }
 
 ExecutionEngine::ExecutionEngine(QQmlJS::EvalISelFactory *factory)
@@ -807,7 +806,7 @@ QmlExtensions *ExecutionEngine::qmlExtensions()
     return m_qmlExtensions;
 }
 
-void ExecutionEngine::throwException(const ValueRef value)
+ReturnedValue ExecutionEngine::throwException(const ValueRef value)
 {
 //    Q_ASSERT(!hasException);
     hasException = true;
@@ -822,6 +821,7 @@ void ExecutionEngine::throwException(const ValueRef value)
     if (debugger)
         debugger->aboutToThrow(value);
 
+    return Encode::undefined();
 }
 
 ReturnedValue ExecutionEngine::catchException(ExecutionContext *catchingContext, StackTrace *trace)