Joshua Branson <jbranso@dismail.de> writes:

> Hello I am getting a weird mesa assertion when I try to start sway.
>
> sway: ../mesa-18.3.5/src/mesa/program/prog_parameter.c:247:
> _mesa_add_parameter: Assertion `0 < size && size <=4' failed.
> Aborted.
>
> Is anyone else getting this issue?

I've seen this too and went as far as bisecting Mesa:
<https://bugs.freedesktop.org/show_bug.cgi?id=110608>.

...after bisecting Guix to e6a668ec7303a71f87e4c9354b1458e555058c63.

(Guix makes this process surprisingly easy btw, someone should write a
blog post about it.)

The fix is to wipe Mesas shader cache:

 $ rm -rf "$HOME/.cache/mesa_shader_cache"

You may also need to do the same for your display manager, if any:

 $ sudo rm -rf "/var/lib/{sddm,gdm}/.cache/mesa_shader_cache"

I don't know why Mesa fails to do that on its own.  I can't find a lot
on the internet about this issue, so I suspect it is a problem specific
to Guix.