[Development] Differences: QDesktopServices vs QStandardPaths

[Chris W]

Hello,

Were the following differences between the paths returned by Qt 4.8
QDesktopServices and 5.1 QStandardPaths intentional or bug-worthy? (They
are annoying either way)

#include <QtCore>
#include <QDesktopServices>
int main(int argc, char **argv)
{
QCoreApplication app(argc, argv);
app.setOrganizationName("ExampleOrg");
app.setOrganizationDomain("example.com.au");
app.setApplicationName("ExampleApp");
#if QT_VERSION >= QT_VERSION_CHECK(5,0,0)
QStringList paths =
QStandardPaths::standardLocations(QStandardPaths::DataLocation);
#else
QString paths =
QDesktopServices::storageLocation(QDesktopServices::DataLocation);
#endif
qDebug() << qVersion() << paths;
return 0;
}

Outputs under different Qt versions on 64-bit Linux:
4.8.4 "/home/chrisw/.local/share/data/ExampleOrg/ExampleApp"
5.1.0 ("/home/chrisw/.local/share/ExampleOrg/ExampleApp",
"/usr/share/ExampleOrg/ExampleApp",
"/usr/local/share/ExampleOrg/ExampleApp",
"/usr/share/ExampleOrg/ExampleApp")

Note the extra “data” directory in the Qt4 path vs. the first directory
in Qt5. XDG_DATA_HOME is not set.

This means ported Qt4-based code, when built with Qt5, looks in the
wrong location for data that was previously installed/generated in the
Qt4 DataLocation on deployed machines. As sierdzio points out here
(http://qt-project.org/forums/viewthread/29223/) this is strictly
neither a regression in QDesktopServices nor a bug in QStandardPaths.
Aligning it now would be a regression in Qt5.

Unless there's something I am missing, I will work around it by moving
the data using an installer script, using the deprecated function in
QDesktopServices, or coding alternate paths into the
application startup.

-- 
Chris Williams

Life would be much easier if I had the source code.  Anon.