Skip block context within call contexts when searching for parameters

Only the call context contains the signal parameters. However, there can
be any number of nested block contexts in a function. This manifests
itself when the function needs an execution context. The simplest way to
trigger this is attaching a debugger.

Fixes: QTBUG-75393
Change-Id: Iabdc06a9fe7bf88204525d6940b626575fee1579
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 38 insertions, 5 deletions

diff --git a/src/qml/jsruntime/qv4qmlcontext.cpp b/src/qml/jsruntime/qv4qmlcontext.cpp
index 12ada7ee70..0c5226d46c 100644
--- a/src/qml/jsruntime/qv4qmlcontext.cpp
+++ b/src/qml/jsruntime/qv4qmlcontext.cpp
@@ -458,11 +458,17 @@ ReturnedValue QQmlContextWrapper::resolveQmlContextPropertyLookupGetter(Lookup *
     // into the handler expression through the locals of the call context. So for onClicked: { ... }
     // the parameters of the clicked signal are injected and we must allow for them to be found here
     // before any other property from the QML context.
-    ExecutionContext &ctx = static_cast<ExecutionContext &>(engine->currentStackFrame->jsFrame->context);
-    if (ctx.d()->type == Heap::ExecutionContext::Type_CallContext) {
-        uint index = ctx.d()->internalClass->indexOfValueOrGetter(name);
-        if (index < UINT_MAX)
-            return static_cast<Heap::CallContext*>(ctx.d())->locals[index].asReturnedValue();
+    for (Heap::ExecutionContext *ctx = engine->currentContext()->d(); ctx; ctx = ctx->outer) {
+        if (ctx->type == Heap::ExecutionContext::Type_CallContext) {
+            const uint index = ctx->internalClass->indexOfValueOrGetter(name);
+            if (index < std::numeric_limits<uint>::max())
+                return static_cast<Heap::CallContext *>(ctx)->locals[index].asReturnedValue();
+        }
+
+        // Skip only block contexts within the current call context.
+        // Other contexts need a regular QML property lookup. See below.
+        if (ctx->type != Heap::ExecutionContext::Type_BlockContext)
+            break;
     }
 
     bool hasProperty = false;
diff --git a/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp b/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp
index b75fb6b895..497c721f50 100644
--- a/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp
+++ b/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp
@@ -322,6 +322,8 @@ private slots:
     void lastLineOfConditional();
 
     void readThis();
+    void signalParameters();
+
 private:
     QV4Debugger *debugger() const
     {
@@ -899,6 +901,31 @@ void tst_qv4debugger::readThis()
     QCOMPARE(a.value("value").toInt(), 5);
 }
 
+void tst_qv4debugger::signalParameters()
+{
+    QQmlEngine engine;
+    QV4::ExecutionEngine *v4 = engine.handle();
+    v4->setDebugger(new QV4Debugger(v4));
+
+    QQmlComponent component(&engine);
+    component.setData("import QtQml 2.12\n"
+                      "QtObject {\n"
+                      "    id: root\n"
+                      "    property string result\n"
+                      "    signal signalWithArg(string textArg)\n"
+                      "    property Connections connections : Connections {\n"
+                      "        target: root\n"
+                      "        onSignalWithArg: { root.result = textArg; }\n"
+                      "    }\n"
+                      "    Component.onCompleted: signalWithArg('something')\n"
+                      "}", QUrl("test.qml"));
+
+    QVERIFY(component.isReady());
+    QScopedPointer<QObject> obj(component.create());
+    QVERIFY(obj);
+    QCOMPARE(obj->property("result").toString(), QLatin1String("something"));
+}
+
 QTEST_MAIN(tst_qv4debugger)
 
 #include "tst_qv4debugger.moc"