[Development] Compatability break in QUrl in Qt 4.8

[shane.kearns at accenture.com]

> Fair enough.
>
> Other opinions around? Olivier has already said he's for reverting to
> the old
> 4.7 behaviour.
>
The documentation note about the dangers of constructing QUrl from QString was already there in 4.6 (at the bottom of the page)
However, QT_NO_URL_CAST_FROM_STRING is not defined by default, so there are no compiler errors or warnings when using unsafe construction.

So I'm ambivalent when it comes to C++ applications.

What has convinced me is the Qt Creator HTML5 app wizard generates this kind of unsafe code.
I would assume that many users of this app wizard are web developers with limited c++ skills, and in any case would expect the boilerplate generated by the SDK to be good.

So I am in favour of keeping the 4.7 behaviour in 4.x releases.
I'd also be in favour of making QT_NO_URL_CAST_FROM_STRING turned on by default in 5.x (i.e. you need to define QT_ALLOW_URL_CAST_FROM_STRING to allow those assignments)

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    Html5ApplicationViewer viewer;
    viewer.setOrientation(Html5ApplicationViewer::ScreenOrientationAuto);
    viewer.showExpanded();
    viewer.loadFile(QLatin1String("html/index.html")); // <-- relative path

    return app.exec();
}

QString Html5ApplicationViewerPrivate::adjustPath(const QString &path)
{
#ifdef Q_OS_UNIX
#ifdef Q_OS_MAC
    if (!QDir::isAbsolutePath(path))
        return QCoreApplication::applicationDirPath()
                + QLatin1String("/../Resources/") + path;
#else
    const QString pathInInstallDir = QCoreApplication::applicationDirPath()
        + QLatin1String("/../") + path;
    if (pathInInstallDir.contains(QLatin1String("opt"))
            && pathInInstallDir.contains(QLatin1String("bin"))
            && QFileInfo(pathInInstallDir).exists()) { // <-- condition is false on symbian
        return pathInInstallDir;
    }
#endif
#endif
    return path; // <-- path is unmodified
}

void Html5ApplicationViewer::loadFile(const QString &fileName)
{
    m_d->m_webView->setUrl(QUrl(Html5ApplicationViewerPrivate::adjustPath(fileName))); // <-- QT_NO_URL_CAST_FROM_STRING wouldn't have helped, but it should still be using QUrl::fromLocalFile
}

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