Export fails to work with symlinked files

[wavexx]

Using Shotcut 24.03.01 from debian unstable.

Try the following:

• take any mp4 file, say "input.mp4"
• make a symlink to "test.mp4"
• shotcut test.mp4 opens the file, everything works

Now load the same symlink as a playlist, even twice:

• shotcut test.mp4 test.mp4
• shotcut starts with two items in theplaylist
• add one to the timeline
• try to export
• shotcut now fails with "Your project is missing some files", even though edit/playback is fine.
• Saving/re-opening the project can't solve anything (file exist and are the symlinks are working)

[ddennedy]

Reproduced and log shows [Error ] <MltXmlChecker::checkUnlinkedFile> file not found: "/tmp/link.mp4" even though /tmp is not my working directory. A workaround is supply the full path to the input files as command line arguments. Most users are not using the command line arguments and do not suffer this. This happens because the directory for the temporary XML file export generates is in /tmp. Basically, the Qt function QFileInfo::exists() we use is given a relative path, and checks the temp file's location instead of the working directory. But also melt will have a problem because it treats relative paths as relative to the document location. Overall, this bug is unrelated to whether the file is real or a symlink. It is also unrelated to whether you add anything to the timeline.