Expose let/const variables from imported JS scripts

This patch allows QML to access let/const variables defined in JS files.

Detailed changes:

  - The recently added ContextType::ScriptImportedByQML is changed to avoid
    creating Push/PopScriptContext instructions, similar to
    ContextType::ESModule.

  - QV4::Module is changed to also work with CompilationUnits which are not
    ESModules. In this case QV4::Module will behave as if all lexically scoped
    variables were exported.

  - CompilationUnit is changed to support instantiating and evaluating
    QV4::Modules for non-ESModules as well.

  - QQmlTypeLoader is changed to always create QV4::Modules for evaluating
    scripts. For the non-ESModule case, the QV4::Module is evaluated inside a
    QV4::QmlContext, as before.

  - A pointer to the QV4::Module is added to QV4::QQmlContextWrapper, and used
    in virtualGet to access the let/const variables in the CallContext. Access
    is read-only.

Fixes: QTBUG-69408
Change-Id: I6f299363fdf5e1c5a4a0f1d9e655b4dc5112dd00
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 16 insertions, 20 deletions

diff --git a/src/qml/compiler/qv4compileddata.cpp b/src/qml/compiler/qv4compileddata.cpp
index 244e762faf..39f48f67f8 100644
--- a/src/qml/compiler/qv4compileddata.cpp
+++ b/src/qml/compiler/qv4compileddata.cpp
@@ -381,13 +381,20 @@ QStringList CompilationUnit::moduleRequests() const
 
 Heap::Module *CompilationUnit::instantiate(ExecutionEngine *engine)
 {
-    if (m_module)
+    if (isESModule() && m_module)
         return m_module;
 
+    if (data->indexOfRootFunction < 0)
+        return nullptr;
+
     if (!this->engine)
         linkToEngine(engine);
 
-    m_module = engine->memoryManager->allocate<Module>(engine, this);
+    Scope scope(engine);
+    Scoped<Module> module(scope, engine->memoryManager->allocate<Module>(engine, this));
+
+    if (isESModule())
+        m_module = module->d();
 
     for (const QString &request: moduleRequests()) {
         auto dependentModuleUnit = engine->loadModule(QUrl(request), this);
@@ -396,7 +403,6 @@ Heap::Module *CompilationUnit::instantiate(ExecutionEngine *engine)
         dependentModuleUnit->instantiate(engine);
     }
 
-    Scope scope(engine);
     ScopedString importName(scope);
 
     const uint importCount = data->importEntryTableSize;
@@ -431,7 +437,7 @@ Heap::Module *CompilationUnit::instantiate(ExecutionEngine *engine)
         }
     }
 
-    return m_module;
+    return module->d();
 }
 
 const Value *CompilationUnit::resolveExport(QV4::String *exportName)
@@ -556,10 +562,13 @@ void CompilationUnit::getExportedNamesRecursively(QStringList *names, QVector<co
 
 void CompilationUnit::evaluate()
 {
-    if (m_moduleEvaluated)
-        return;
-    m_moduleEvaluated = true;
+    QV4::Scope scope(engine);
+    QV4::Scoped<Module> module(scope, m_module);
+    module->evaluate();
+}
 
+void CompilationUnit::evaluateModuleRequests()
+{
     for (const QString &request: moduleRequests()) {
         auto dependentModuleUnit = engine->loadModule(QUrl(request), this);
         if (engine->hasException)
@@ -568,19 +577,6 @@ void CompilationUnit::evaluate()
         if (engine->hasException)
             return;
     }
-
-    QV4::Function *moduleFunction = runtimeFunctions[data->indexOfRootFunction];
-    CppStackFrame frame;
-    frame.init(engine, moduleFunction, nullptr, 0);
-    frame.setupJSFrame(engine->jsStackTop, Value::undefinedValue(), m_module->scope,
-                       Value::undefinedValue(), Value::undefinedValue());
-
-    frame.push();
-    engine->jsStackTop += frame.requiredJSStackFrameSize();
-    auto frameCleanup = qScopeGuard([&frame]() {
-       frame.pop();
-    });
-    Moth::VME::exec(&frame, engine);
 }
 
 bool CompilationUnit::loadFromDisk(const QUrl &url, const QDateTime &sourceTimeStamp, QString *errorString)