Wt

This was raised in the Help forum by a colleague, but it feels like a bug.

We are upgrading from Wt 4.5.0 to 4.6.1, and since the upgrade, we see the following JS error:

Uncaught TypeError: Cannot read properties of undefined (reading 'setLocale')

settings?wtd=h91zWlSU7eto6jQq&sid=876614815&webGL=true&scrW=1920&scrH=975&tz=0&tzS=Europe%2FLondon&htmlHistory=true&deployPath=%2F&request=script&rand=1076529179:234 Uncaught TypeError: Cannot read properties of undefined (reading 'setLocale')
    at eval (eval at Ea (settings?wtd=h91zWlSU7eto6jQq&sid=876614815&webGL=true&scrW=1920&scrH=975&tz=0&tzS=Europe%2FLondon&htmlHistory=true&deployPath=%2F&request=script&rand=1076529179:233:285), <anonymous>:19:28)
    at eval (eval at Ea (settings?wtd=h91zWlSU7eto6jQq&sid=876614815&webGL=true&scrW=1920&scrH=975&tz=0&tzS=Europe%2FLondon&htmlHistory=true&deployPath=%2F&request=script&rand=1076529179:233:285), <anonymous>:48:4)
    at eval (<anonymous>)
    at Ea (settings?wtd=h91zWlSU7eto6jQq&sid=876614815&webGL=true&scrW=1920&scrH=975&tz=0&tzS=Europe%2FLondon&htmlHistory=true&deployPath=%2F&request=script&rand=1076529179:233:285)
    at O (settings?wtd=h91zWlSU7eto6jQq&sid=876614815&webGL=true&scrW=1920&scrH=975&tz=0&tzS=Europe%2FLondon&htmlHistory=true&deployPath=%2F&request=script&rand=1076529179:234:87)
    at u (settings?wtd=h91zWlSU7eto6jQq&sid=876614815&webGL=true&scrW=1920&scrH=975&tz=0&tzS=Europe%2FLondon&htmlHistory=true&deployPath=%2F&request=script&rand=1076529179:165:160)
    at XMLHttpRequest.v (settings?wtd=h91zWlSU7eto6jQq&sid=876614815&webGL=true&scrW=1920&scrH=975&tz=0&tzS=Europe%2FLondon&htmlHistory=true&deployPath=%2F&request=script&rand=1076529179:165:354)

As indicated above, in our the error is triggered by a call to setlocale(...), but it
appears that any call to WApplication::refresh() will trigger a similar error.

My colleague prepared the following minimal app that reproduces the error:

#include <QCoreApplication>
#include "wtqt/WQApplication.h"
#include <Wt/WTimeEdit.h>

class MyApplication : public Wt::WQApplication
{
public:
    MyApplication(const Wt::WEnvironment &env);
    ~MyApplication();

    virtual void create();
    virtual void destroy();
};

MyApplication::MyApplication(const Wt::WEnvironment &env)
    : Wt::WQApplication(env, true)
{
}

MyApplication::~MyApplication()
{
}

void MyApplication::create()
{
    root()->addNew<Wt::WTimeEdit>();
    refresh();
}

void MyApplication::destroy()
{
}

Wt::WApplication *createApplication(const Wt::WEnvironment& env)
{
    return new MyApplication(env);
}

int main(int argc, char **argv)
{
    QCoreApplication a(argc, argv);

    return Wt::WRun(argc, argv, [](const Wt::WEnvironment& env) {
      return std::make_unique<MyApplication>(env);
    });
}

The JS error does not occur if a WApplication is used instead of a WQApplication.

It feels very similar to an error I raised against Wt 3.3.x a few years ago (since fixed): https://redmine.webtoolkit.eu/boards/2/topics/11782?r=11860#message-11860

This is currently blocking our upgrade to a more recent Wt release.

Let me know if you need any additional information.

Thanks,

Chris.