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, 4 insertions, 4 deletions

diff --git a/src/qml/compiler/qv4compilercontext.cpp b/src/qml/compiler/qv4compilercontext.cpp
index 572f24f148..ca4cbfc4fc 100644
--- a/src/qml/compiler/qv4compilercontext.cpp
+++ b/src/qml/compiler/qv4compilercontext.cpp
@@ -207,7 +207,7 @@ void Context::emitBlockHeader(Codegen *codegen)
             blockIndex = codegen->module()->blocks.count() - 1;
         }
 
-        if (contextType == ContextType::Global || contextType == ContextType::ScriptImportedByQML) {
+        if (contextType == ContextType::Global) {
             Instruction::PushScriptContext scriptContext;
             scriptContext.index = blockIndex;
             bytecodeGenerator->addInstruction(scriptContext);
@@ -222,7 +222,7 @@ void Context::emitBlockHeader(Codegen *codegen)
                 blockContext.index = blockIndex;
                 bytecodeGenerator->addInstruction(blockContext);
             }
-        } else if (contextType != ContextType::ESModule) {
+        } else if (contextType != ContextType::ESModule && contextType != ContextType::ScriptImportedByQML) {
             Instruction::CreateCallContext createContext;
             bytecodeGenerator->addInstruction(createContext);
         }
@@ -316,9 +316,9 @@ void Context::emitBlockFooter(Codegen *codegen)
 
 QT_WARNING_PUSH
 QT_WARNING_DISABLE_GCC("-Wmaybe-uninitialized") // the loads below are empty structs.
-    if (contextType == ContextType::Global || contextType == ContextType::ScriptImportedByQML)
+    if (contextType == ContextType::Global)
         bytecodeGenerator->addInstruction(Instruction::PopScriptContext());
-    else if (contextType != ContextType::ESModule)
+    else if (contextType != ContextType::ESModule && contextType != ContextType::ScriptImportedByQML)
         bytecodeGenerator->addInstruction(Instruction::PopContext());
 QT_WARNING_POP
 }