Strange behaviour of QFutureWatcher on windows

I was running into problems in release mode in some threaded code and narrowed down the problem to the following lines.

Code:

---

QFutureWatcher<Result> watcher;
QList<Job> jobs;
...
if(jobs.isEmpty() || watcher.isStarted() && !watcher.isFinished())
	return;
watcher.setFuture(QtConcurrent::run(..., jobs.takeFirst()));

---

The problem is that the first time this code is run(watcher is only default constructed) the expression "watcher.isStarted() && !watcher.isFinished()" evaluates to true, but only in release mode.

After sifting through some code I found out that the trolls decided that a default constructed QFuture is supposed to have the states Started | Finished | Canceled, which might be a bit counter-intuitive, but is fine by me.

The problem is that the following program:

Code:

---

#include <QDebug>
#include <QFutureWatcher>
 
int main()
{
	QFutureWatcher<int> watcher;
	qDebug()<<"isStarted()"<<watcher.isStarted();
	qDebug()<<"isFinished()"<<watcher.isFinished();
	qDebug()<<"isCanceled()"<<watcher.isCanceled();
	return 1;
}

---

gives the following output in release mode:

Code:

---

isStarted() true
isFinished() false
isCanceled() true

---

whereas if you exchange QFutureWatcher with QFuture it gives the expected output.

I have tried it with MSVC 2008 and Qt 4.6.2 and would like to here if anyone can confirm this, or even better explain how it can happen.