Details
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Bug
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Resolution: Done
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P3: Somewhat important
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None
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5.12
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None
Description
The following JavaScript throws a type error:
main.cpp
#include <QGuiApplication> #include <QDebug> #include <QJSEngine> class EntityScriptFilter : public QObject { Q_OBJECT public: Q_INVOKABLE explicit EntityScriptFilter(QObject *parent = nullptr) : QObject(parent) {} void requireId(quint64 id) { qDebug() << Q_FUNC_INFO << id; } Q_INVOKABLE void requireName(const QString &name) { qDebug() << Q_FUNC_INFO << name; } };
script.mjs
export function narrate() {
var equipperFilter = new EntityScriptFilter()
equipperFilter.requireId(123)
}
The error says:
"TypeError: Type error"
Which isn't exactly helpful. When debugging the error, I see the following call stack:
1 QV4::ExecutionEngine::throwTypeError() qv4engine.cpp 1078 0x10400e362 2 QV4::Moth::VME::interpret(QV4::CppStackFrame *, QV4::ExecutionEngine *, const char *) qv4vme_moth.cpp 729 0x103d9debc 3 QV4::Moth::VME::exec(QV4::CppStackFrame *, QV4::ExecutionEngine *) qv4vme_moth.cpp 441 0x103d8dede 4 QV4::ArrowFunction::virtualCall(QV4::FunctionObject const *, QV4::Value const *, QV4::Value const *, int) qv4functionobject.cpp 519 0x103bbf6bd 5 QV4::FunctionObject::call(QV4::Value const *, QV4::Value const *, int) const qv4functionobject_p.h 202 0x103aefc96 6 QV4::FunctionObject::call(QV4::JSCallData const&) const qv4jscall_p.h 112 0x103ae8cc2 7 QJSValue::call(QList<QJSValue> const&) qjsvalue.cpp 709 0x103ae8459 8 main main.cpp 33 0x1000048ef 9 start 0x7fff63afa085
Looking at the call site, the problem is made clear:
MOTH_BEGIN_INSTR(CallPropertyLookup)
STORE_IP();
Lookup *l = function->compilationUnit->runtimeLookups + lookupIndex;
// ok to have the value on the stack here
Value f = Value::fromReturnedValue(l->getter(l, engine, stack[base]));
if (Q_UNLIKELY(!f.isFunctionObject())) {
acc = engine->throwTypeError();
goto handleUnwind;
}
acc = static_cast<FunctionObject &>(f).call(stack + base, stack + argv, argc);
CHECK_EXCEPTION;
MOTH_END_INSTR(CallPropertyLookup)
The C++ function is not invokable.
It seems that the engine has the context to print a more descriptive error message. For example:
TypeError: requireId() is not a callable function (is it invokable?)