Control: reassign -1 libqt5gui5-gles 5.15.2+dfsg-3 Control: retitle -1 apt replaces libqt5gui5 with libqt5gui5-gles on upgrade On Fri, Dec 11, 2020 at 09:29:04PM +0300, Dmitry Shachnev wrote: > Thanks for the detailed bug report and the blog post link! > > If you are using amd64 desktop then you would almost never need > libqt5quick5-gles. These packages are mostly needed for ARM64 users, or for > users of video cards that support OpenGL ES but not desktop OpenGL. > > See my blog post for details: > > https://mitya57.me/weblog/2020/01/qt-opengl-es-packages-available.html > > However, it would be nice to know why users end up with the -gles packages > installed. Your case is not the only one, here is a similar story: > > https://www.reddit.com/r/debian/comments/jpm3bn/after_doing_a_distupgrade_i_no_longer_have_icons/ > > For the record, let me put together some links I found via your blog post: > > - https://askubuntu.com/q/1288506 > - https://www.reddit.com/r/kde/comments/jhqbnz/kde_plasma_rendering_problem_black_squares/ > - https://ubuntuforums.org/showthread.php?t=2442842 > > All dependencies should be in a form like libqt5gui5 | libqt5gui5-gles, so > apt should fall back to the latter package only if the former is not available > for some reason. So I want to understand what that reason is. Thanks to the Ubuntu user who sent me their log, I think I finally found the cause of this bug. This cause is the qt5-default package. We removed it because it is no longer needed. But the latest version of that package that ever existed has this dependency: Depends: qtbase5-dev (= 5.14.2+dfsg-5) | qtbase5-gles-dev (>= 5.14.2+dfsg) The latest available version of qtbase5-dev cannot satisfy that dependency, but the latest version of qtbase5-gles-dev can! So for people who had qt5-default installed, apt will try to replace the normal Qt stack with -gles one to keep that dependency satisfied. Apparently it will do it even if qt5-default will be eventually removed anyway. I am attaching a log when this happens when trying to upgrade from an August 2020 testing snapshot (with qt5-default installed) to the current testing. As a solution to this problem, I will add “Breaks: qt5-default” to libqt5gui5-gles and to qtbase5-gles-dev. This should convince apt to not consider these packages as a way to satisfy qt5-default dependency. This bug should not affect upgrades from Buster to Bullseye, as the Buster version of qt5-default had a dependency on qtbase5-dev only. So it only affects upgrades from old (pre Oct 2020) testing/sid to modern testing/sid. -- Dmitry Shachnev
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