From 42aa031a16522bdcabe166881205bfa4607da693 Mon Sep 17 00:00:00 2001
From: Olivier Goffart <ogoffart@trolltech.com>
Date: Mon, 3 Aug 2009 16:06:30 +0200
Subject: QScriptContext::calledAsConstructor also works with non-native
 function

Use the opcode to see if it was called with op_construct

This could also work with native function, but not when they are called
with  QScriptValue::call() or QScriptValue::construct()
---
 src/script/api/qscriptcontext.cpp                | 26 +++++++++++++++----
 tests/auto/qscriptcontext/tst_qscriptcontext.cpp | 33 ++++++++++++++++++++----
 2 files changed, 49 insertions(+), 10 deletions(-)

diff --git a/src/script/api/qscriptcontext.cpp b/src/script/api/qscriptcontext.cpp
index d68b913..99b8989 100644
--- a/src/script/api/qscriptcontext.cpp
+++ b/src/script/api/qscriptcontext.cpp
@@ -330,20 +330,36 @@ QScriptValue QScriptContext::argumentsObject() const
 */
 bool QScriptContext::isCalledAsConstructor() const
 {
-    const JSC::CallFrame *frame = reinterpret_cast<const JSC::CallFrame *>(this);
-    //look up for the QScriptActivationObject and its calledAsConstructor flag.
+    JSC::CallFrame *frame = reinterpret_cast<JSC::CallFrame *>(const_cast<QScriptContext *>(this));
+
+    //For native functions, look up for the QScriptActivationObject and its calledAsConstructor flag.
     JSC::ScopeChainNode *node = frame->scopeChain();
     JSC::ScopeChainIterator it(node);
     for (it = node->begin(); it != node->end(); ++it) {
-        if (!(*it)->isVariableObject()) {
+        if ((*it)->isVariableObject()) {
             if ((*it)->inherits(&QScript::QScriptActivationObject::info)) {
                 return static_cast<QScript::QScriptActivationObject *>(*it)->d_ptr()->calledAsConstructor;
             }
             //not a native function
-            //### we have no way to know if is is or not a constructor
-            return false; 
+            break;
         }
     }
+
+    //Not a native function, try to look up in the bytecode if we where called from op_construct
+    JSC::Instruction* returnPC = frame->returnPC();
+
+    if (!returnPC)
+        return false;
+
+    JSC::CallFrame *callerFrame = reinterpret_cast<JSC::CallFrame *>(parentContext());
+    if (!callerFrame)
+        return false;
+
+    if (returnPC[-JSC::op_construct_length].u.opcode == frame->interpreter()->getOpcode(JSC::op_construct)) {
+        //We are maybe called from the op_construct opcode which has 6 opperands.
+        //But we need to check we are not called from op_call with 4 opperands (by checking the argc operand)
+        return returnPC[-4].u.operand == frame->argumentCount();
+    }
     return false;
 }
 
diff --git a/tests/auto/qscriptcontext/tst_qscriptcontext.cpp b/tests/auto/qscriptcontext/tst_qscriptcontext.cpp
index 4726815..7a363ac 100644
--- a/tests/auto/qscriptcontext/tst_qscriptcontext.cpp
+++ b/tests/auto/qscriptcontext/tst_qscriptcontext.cpp
@@ -764,15 +764,21 @@ static QScriptValue storeCalledAsConstructorV2(QScriptContext *ctx, QScriptEngin
     return eng->undefinedValue();
 }
 
+static QScriptValue storeCalledAsConstructorV3(QScriptContext *ctx, QScriptEngine *eng)
+{
+    ctx->callee().setProperty("calledAsConstructor", ctx->parentContext()->isCalledAsConstructor());
+    return eng->undefinedValue();
+}
+
 void tst_QScriptContext::calledAsConstructor()
 {
     QScriptEngine eng;
+    QScriptValue fun1 = eng.newFunction(storeCalledAsConstructor);
     {
-        QScriptValue fun = eng.newFunction(storeCalledAsConstructor);
-        fun.call();
-        QVERIFY(!fun.property("calledAsConstructor").toBool());
-        fun.construct();
-        QVERIFY(fun.property("calledAsConstructor").toBool());
+        fun1.call();
+        QVERIFY(!fun1.property("calledAsConstructor").toBool());
+        fun1.construct();
+        QVERIFY(fun1.property("calledAsConstructor").toBool());
     }
     {
         QScriptValue fun = eng.newFunction(storeCalledAsConstructorV2, (void*)0);
@@ -781,6 +787,23 @@ void tst_QScriptContext::calledAsConstructor()
         fun.construct();
         QVERIFY(fun.property("calledAsConstructor").toBool());
     }
+    {
+        eng.globalObject().setProperty("fun1", fun1);
+        eng.evaluate("fun1();");
+        QVERIFY(!fun1.property("calledAsConstructor").toBool());
+        eng.evaluate("new fun1();");
+        QVERIFY(fun1.property("calledAsConstructor").toBool());
+    }
+    {
+        QScriptValue fun3 = eng.newFunction(storeCalledAsConstructorV3);
+        eng.globalObject().setProperty("fun3", fun3);
+        eng.evaluate("function test() { fun3() }");
+        eng.evaluate("test();");
+        QVERIFY(!fun3.property("calledAsConstructor").toBool());
+        eng.evaluate("new test();");
+        QVERIFY(fun3.property("calledAsConstructor").toBool());
+    }
+
 }
 
 static QScriptValue argumentsObjectInNative_test1(QScriptContext *ctx, QScriptEngine *)
-- 
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