Do not use QScriptEngine::push/popScope in rule evaluation

This functionality is undocumented, has its flaws and is unavailable in
other JS engines. Use the following pattern instead to inject global
variables without polluting the global namespace:
    QScriptValue g = engine.newObject();
    g.setPrototype(engine.globalObject());
    // set properties on g
    engine.setGlobalObject(g);
    engine.evaluate(...);
    engine.setGlobalObject(g.prototype());

Change-Id: I5f92da8cccfa23c3722740c1852a71fd50e8eb8a
Reviewed-by: Christian Kandeler <christian.kandeler@theqtcompany.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/src/lib/corelib/buildgraph/rulesevaluationcontext.cpp b/src/lib/corelib/buildgraph/rulesevaluationcontext.cpp
index 1b7efb33c..47088eb17 100644
--- a/src/lib/corelib/buildgraph/rulesevaluationcontext.cpp
+++ b/src/lib/corelib/buildgraph/rulesevaluationcontext.cpp
@@ -49,6 +49,7 @@ RulesEvaluationContext::RulesEvaluationContext(const Logger &logger)
     : m_engine(new ScriptEngine(logger)), m_observer(0), m_initScopeCalls(0)
 {
     m_prepareScriptScope = m_engine->newObject();
+    m_prepareScriptScope.setPrototype(m_engine->globalObject());
     ProcessCommand::setupForJavaScript(m_prepareScriptScope);
     JavaScriptCommand::setupForJavaScript(m_prepareScriptScope);
 }
@@ -87,10 +88,9 @@ void RulesEvaluationContext::initScope()
         return;
 
     m_engine->clearImportsCache();
-    m_engine->pushContext();
     m_scope = m_engine->newObject();
     m_scope.setPrototype(m_prepareScriptScope);
-    m_engine->currentContext()->pushScope(m_scope);
+    m_engine->setGlobalObject(m_scope);
 }
 
 void RulesEvaluationContext::cleanupScope()
@@ -100,8 +100,7 @@ void RulesEvaluationContext::cleanupScope()
         return;
 
     m_scope = QScriptValue();
-    m_engine->currentContext()->popScope();
-    m_engine->popContext();
+    m_engine->setGlobalObject(m_prepareScriptScope.prototype());
 }
 
 RulesEvaluationContext::Scope::Scope(RulesEvaluationContext *evalContext)