Describe and hack around the Seafile problem.

shell-seafile.nix

@@ -1,5 +1,5 @@
 with import <nixpkgs> {};
 stdenv.mkDerivation {
   name = "seafile";
-  buildInputs = [ seafile-client ];
+  buildInputs = [ seafile-shared ];
 }

work-notes.org

@@ -21,6 +21,76 @@
   6. Run =nix-shell [[file:shell-seafile.nix][shell-seafile.nix]]= and, within it,
      =seafile-applet= to sync the changes to the server.
 
+* Seafile problem <2020-02-17 Mon>
+** Problem
+   After another update, Seafile started telling me this when I tried
+   to start it:
+   #+BEGIN_QUOTE
+   qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
+   This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
+
+   Aborted (core dumped)
+   #+END_QUOTE
+
+   I did a couple hours of searching, and found some threads, which did
+   not help:
+
+   - https://github.com/NixOS/nixpkgs/issues/42893
+
+     Idea: imperatively install Seafile and then tell it where to
+     search for plugin:
+     #+BEGIN_SRC shell
+nix-env -iA nixpkgs.qt5.qtbase
+export XDG_DATA_DIRS=$HOME/.nix-profile/share:$XDG_DATA_DIRS
+     #+END_SRC
+     Tried this literally, got
+     #+BEGIN_QUOTE
+     error: attribute 'nixpkgs' in selection path 'nixpkgs.qt5.qtbase' not found
+     #+END_QUOTE
+
+   - https://github.com/NixOS/nixpkgs/issues/65399
+
+     There is a new way to describe Qt packages which correctly handles
+     looking for plugins, this issue is there to help track all the
+     problems that this may lead to.  There is [[https://hydra.nixos.org/build/96804884/download/1/nixpkgs/manual.html#sec-language-qt][some documentation]] as to
+     how to do it properly.  I didn't feel like hacking Nixpkgs right
+     away.
+
+   - https://forum.qt.io/topic/111553/solved-qt-qpa-plugin-could-not-find-the-qt-platform-plugin-xcb-in/7
+
+     Tell Seafile where to look for plugins.  This is not necessarily
+     even applicable with Nix.
+
+   - https://github.com/haiwen/seafile/issues/6
+
+     Apparently, Seafile has a CLI interface, but I don't find it in
+     my installation.  More concretely, the file =seafile-cli= appears
+     in shell completions, but it doesn't launch nor could I find
+     where it was.
+
+** My hack <2020-02-17 Mon>
+   My current hack consists in the following modifications:
+
+   1. Add =qt5.qtbase= and =seafile-client= to =home.packages= in
+      [[/home/scolobb/.config/nixpkgs/home.nix][=home.nix=]].
+
+   2. Install =seafile-shared= instead of =seafile-client= in
+      [[file:shell-seafile.nix][=shell-seafile.nix=]].
+
+   Very weirdly, this makes =seafile-applet= work.  I tried not doing
+   (1) and putting all the packages in [[file:shell-seafile.nix][=shell-seafile.nix=]], but it
+   won't work.  Also, again weirdly, outside of Nix shell the
+   =seafile-applet= coming from the home-manager installation never
+   gets past the message
+   #+BEGIN_QUOTE
+   lang = English, translation = (null), locale.name() = en_US
+   #+END_QUOTE
+   without showing the interface or doing whatsoever.
+
+** Proper solution?
+   A proper solution would probably consist in updating the Seafile
+   package to comply with the new [[https://hydra.nixos.org/build/96804884/download/1/nixpkgs/manual.html#sec-language-qt][way to describe Qt packages]].
+
 * Removing the publish cache
   Org-publish will not detect files being deleted from the output.  To
   force it to clear its caches, do the following: