bug#35594: GNOME: Application icons are not displayed immediately after installation

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

Hello,

sirgazil <sirgazil@zoho.com> writes:

> Hi,
>
> I installed the GNU system in a real machine using Guix 1.0 ISO
> installer
> (https://ftp.gnu.org/gnu/guix/guix-system-install-1.0.0.x86_64-linux.iso.xz).
>
> Whenever I install a desktop application, the application icon does
> not show up immediately in the list of available applications. I have
> to log out and log in again to be able to see it.
>
>
> ## Steps to reproduce
>
> 1. Install a desktop application (I tried GIMP, Scribus, Inkscape, Audacity)
> 2. Click on "Activities".
> 3. Click on "Show Applications" (the button with nine dots).
>
>
> ## Unexpected result
>
> The icon of the installed application is not in the list.
>
>
> ## Expected result.
>
> The icon of the installed application is in the list.

After asking in the #gnome channel on freenode, the problem is likely
caused by GNOME Shell using inotify to watch the $XDG_DATA_DIRS
referenced $HOME/.guix-profile/share/applications directory.   The
problem is that the inode of such directory will never change, as it
points to the current profile under /gnu/store:

--8<---------------cut here---------------start------------->8---
$ ls -id $HOME/.guix-profile/share/applications
72653730 /home/maxim/.guix-profile/share/applications/
maxim@hurd ~/src/guix$ realpath $HOME/.guix-profile/share/applications
/gnu/store/ph6a7fy735w5nycmf3za77m6v3g0r7xb-profile/share/applications
maxim@hurd ~/src/guix$ ls -id /gnu/store/ph6a7fy735w5nycmf3za77m6v3g0r7xb-profile/share/applications
72653730 /gnu/store/ph6a7fy735w5nycmf3za77m6v3g0r7xb-profile/share/applications/
--8<---------------cut here---------------end--------------->8---

Any applications making use of inotify to discover changes (to plugins,
for example) is at risk of having the same problem in Guix.

I don't currently have an idea of how we can fix this.

Maxim