VTK fails to build, breaking FreeCAD and others

> As previously discussed during the recent staging cycle, VTK is failing

> to build, which in turn prevents FreeCAD from building:

> Here's what I wrote during the staging cycle:

>

> ------

> For example, the vtk package is broken due to incompatibility with new

> Freetype, which breaks FreeCAD. On #guix, Marius said "I looked into VTK

> before the holidays; the Freetype issue is fixed in version 9, but that

> has other problems, such as making it impossible to unbundle the dozens

> of libraries that we are currently unbundling [...] it is possible to

> backport the VTK commits that fix Freetype compatibility, but it will be

> a lot of work and a huge patch (it was a major cleanup IIRC)." I'm

> CC-ing Ekaitz Zarraga, who has been working on FreeCAD. I'm not sure

> what we can do about this problem in the short term. Marius, can you

> give more info about the bundling problem?

> ------

>

> Ultimately, it seems to be a compatibility issue, combined with

> difficulty of "updating our way out of it". Maybe we should re-instate

> the graft? I know it's icky to think that the graft was masking some

> problem, but is it worse than not having the affected packages at all?

> Were things actually not working while the graft was in place? What do

> you think?

>

> [0] https://lists.gnu.org/archive/html/guix-devel/2021-01/msg00292.html