[Therion] Loch fails on Fedora 30

[Olly Betts]

On Wed, Jul 17, 2019 at 09:22:55PM +0100, James Begley wrote:
> The build of Loch from the copr repository works for me on my fedora 30
> workstation, so I'm guessing that there is an incompatibility with some
> libraries on your laptop and desktop. You say that Loch "no longer works",
> so presumably it used to work? Do you know vaguely when it stopped working?
> Note that the build of Loch in the copr repository hasn't changed since the
> therion 5.4.4 build on the 1st of May, so if Loch was working after that
> date, and isnt working now then it would point to an external library
> problem.
> 
> Your error message points to a problem within the lxR2P.c file (
> https://github.com/therion/therion/blob/master/loch/lxR2P.c) which would
> suggest that the mesa-libGL package might be causing this issue. I've got
> version 19.0.8-1 installed here, which was built on the 26th June (see
> https://koji.fedoraproject.org/koji/packageinfo?packageID=184), but the
> Loch copr package would have been originally built against 19.0.3-1 . Does
> that help? (The mesa changelogs from https://www.mesa3d.org/ don't help me
> very much!).

Currently wxWidgets' OpenGL support requires X and doesn't work with
Wayland.

Fedora now defaults to Wayland, so perhaps Bill is using that default
but James is still using X?

You can override for a single application by running it from a terminal
like so:

GDK_BACKEND=x11 loch

In Survex this workaround is implemented in the aven code, but I don't
see anything equivalent in the therion code.

Cheers,
    Olly