"Could not copy help collection to temporary file" on launch in 4.4.1 u2 beta 1

[apjanke]

When opening Octave.app 4.4.1 u2 beta 1, I and Sebastian get an error message:

Could not copy help collection to temporary file. Search capabilities may be affected. Cannot unregister index tables in file /Applications/Octave-4.4.1.app/Contents/Resources/usr/Cellar/octave-octave-app@4.4.1/4.4.1/share/octave/4.4.1/doc/octave-interpreter.qhc.

[apjanke]

Looks like Qt's help system is trying to write files directly in the program installation location instead of in a system or user temporary directory. If I do this in /Applications/Octave-4.4.1.app:

$ find . -name '*.qhc' | xargs chmod u+w
$ find . -type d -exec chmod u+w "{}" \;

then the error dialog goes away. (Both are necessary; I tried each on their own and the error dialog persisted.)

TODO: Try this against Qt 5.12.7 and 5.14.
TODO: Report this upstream to Qt if it persists in either of those Qt versions.
TODO: If it persists, work around it by opening up write permissions in the app bundle.

[apjanke]

Still happens with Qt 5.12.7.

[apjanke]

Okay, I added this bullshit to octave_app_bundler:

  # Lock down the app M-files and brewed libs to prevent accidental user editing
  chmod -R a-w "$app_build_usr/Cellar"
  # But Qt needs to write to the .qhc files and local dirs when using the help
  # viewer (wtf, Qt?)
  find "$app_build_usr/Cellar/$octave_formula" -name '*.qhc' | xargs chmod u+w
  find "$app_build_usr/Cellar/$octave_formula" -type d -exec chmod u+w "{}" \;

That seemed to work; the error message is gone.

Gonna report this upstream to Qt. This ain't right.

[apjanke]

Reported upstream to Qt: https://bugreports.qt.io/browse/QTBUG-82126

Closing this out, as the workaround seems to be working, and there's nothing else to do for now.