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, 3 deletions

diff --git a/src/lib/corelib/buildgraph/depscanner.cpp b/src/lib/corelib/buildgraph/depscanner.cpp
index 311793f98..9673295e8 100644
--- a/src/lib/corelib/buildgraph/depscanner.cpp
+++ b/src/lib/corelib/buildgraph/depscanner.cpp
@@ -131,6 +131,7 @@ UserDependencyScanner::UserDependencyScanner(const ResolvedScannerConstPtr &scan
 {
     m_engine->setProcessEventsInterval(-1); // QBS-782
     m_global = m_engine->newObject();
+    m_global.setPrototype(m_engine->globalObject());
     setupScriptEngineForFile(m_engine, m_scanner->scanScript->fileContext, m_global);
 }
 
@@ -184,8 +185,7 @@ QStringList UserDependencyScanner::evaluate(Artifact *artifact, const ScriptFunc
     args.append(m_global.property(QString::fromLatin1("product")));
     args.append(artifactConfig);
 
-    QScriptContext *ctx = m_engine->currentContext();
-    ctx->pushScope(m_global);
+    m_engine->setGlobalObject(m_global);
     QScriptValue &function = script->scriptFunction;
     if (!function.isValid() || function.engine() != m_engine) {
         function = m_engine->evaluate(script->sourceCode);
@@ -193,7 +193,7 @@ QStringList UserDependencyScanner::evaluate(Artifact *artifact, const ScriptFunc
             throw ErrorInfo(Tr::tr("Invalid scan script."), script->location);
     }
     QScriptValue result = function.call(QScriptValue(), args);
-    ctx->popScope();
+    m_engine->setGlobalObject(m_global.prototype());
     m_engine->clearRequestedProperties();
     if (Q_UNLIKELY(m_engine->hasErrorOrException(result))) {
         QString msg = Tr::tr("evaluating scan script: ") + m_engine->lastErrorString(result);