Hello all,

I have Guix installed on a foreign distro (Ubuntu 19.10) as a package
manager, and I am attempting to use fonts installed through Guix for
applications installed from Guix, such as Emacs and keepassxc. I have
installed fontconfig and a few font packages. However, I am noticing
that these fonts seem to be interfering with fonts installed via the
system's package manager (APT) and are causing rendering problems in
non-Guix applications such as evince.

The font packages I have installed from Guix are as follows:

--8<---------------cut here---------------start------------->8---
evan@virtualplaza:~$ guix package --list-installed | grep font
font-ubuntu	0.83	out	/gnu/store/6ydn8a96n2zmmrhjckqklfmg83frwl9w-font-ubuntu-0.83
font-gnu-freefont-ttf	20120503	out	/gnu/store/bp0hagiy6j8r0x11r4arsyv7k61lyqfk-font-gnu-freefont-ttf-20120503
font-dejavu	2.37	out	/gnu/store/yr42nyxrqkh89fanvii82br6qil4zcbx-font-dejavu-2.37
gs-fonts	8.11	out	/gnu/store/8ppj83wc1mmrdydh9cy7vqvg0bym8l0q-gs-fonts-8.11
font-adobe-source-han-sans	1.004	jp	/gnu/store/z9mgamhzwnh73w3y7q9flg54gmzr9kx7-font-adobe-source-han-sans-1.004-jp
fontconfig	2.13.1	out	/gnu/store/rkq6ipys8hf5hw66jkzzw4nfr6ncq96a-fontconfig-2.13.1
font-abattis-cantarell	0.111	out	/gnu/store/l0h8n4jn0xhj942gdh28i3rvbbywi613-font-abattis-cantarell-0.111
--8<---------------cut here---------------end--------------->8---

However, when I open a document in evince, the terminal spits out the
following errors about "cairo scaled fonts":

--8<---------------cut here---------------start------------->8---
(evince:19449): Pango-WARNING **: 10:28:58.135: failed to create cairo scaled font, expect ugly output. the offending font is 'Ubuntu 11'

(evince:19449): Pango-WARNING **: 10:28:58.135: font_face status is: <unknown error status>

(evince:19449): Pango-WARNING **: 10:28:58.135: scaled_font status is: out of memory

(evince:19449): Pango-WARNING **: 10:28:58.135: shaping failure, expect ugly output. shape-engine='PangoFcShapeEngine', font='Ubuntu 11', text='●'

(evince:19449): Pango-WARNING **: 10:28:58.142: failed to create cairo scaled font, expect ugly output. the offending font is 'Ubuntu 10.5595703125'

(evince:19449): Pango-WARNING **: 10:28:58.142: font_face status is: <unknown error status>

(evince:19449): Pango-WARNING **: 10:28:58.142: scaled_font status is: out of memory

(evince:19449): Pango-WARNING **: 10:28:58.142: shaping failure, expect ugly output. shape-engine='PangoFcShapeEngine', font='Ubuntu 10.5595703125', text='The quick brown fox jumps over the lazy dog.'

(evince:19449): Pango-WARNING **: 10:28:58.408: failed to create cairo scaled font, expect ugly output. the offending font is 'Ubuntu Italic 11'

(evince:19449): Pango-WARNING **: 10:28:58.408: font_face status is: <unknown error status>

(evince:19449): Pango-WARNING **: 10:28:58.408: scaled_font status is: out of memory

(evince:19449): Pango-WARNING **: 10:28:58.408: shaping failure, expect ugly output. shape-engine='PangoFcShapeEngine', font='Ubuntu Italic 11', text='3'

(evince:19449): Pango-WARNING **: 10:28:58.414: failed to create cairo scaled font, expect ugly output. the offending font is 'Ubuntu Italic 13.1982421875'

(evince:19449): Pango-WARNING **: 10:28:58.414: font_face status is: <unknown error status>

(evince:19449): Pango-WARNING **: 10:28:58.414: scaled_font status is: out of memory

(evince:19449): Pango-WARNING **: 10:28:58.414: shaping failure, expect ugly output. shape-engine='PangoFcShapeEngine', font='Ubuntu Italic 13.1982421875', text='Document contains no annotations'
--8<---------------cut here---------------end--------------->8---

When viewing the application window, all text is replaced by empty white
boxes, as shown in the attached screenshot.