dot has started emitting an error when the Helvetica font is
requested.  I observed the error building fenics-basix, where dot is
used by doxygen to generate image files for the docs, but I can
reproduce the problem with a small example:

$ cat >test.dot << EOF
graph test_graph
{
  node [fontname=Helvetica];
  a -- b;
}
EOF

$ dot test.dot -Tpng -o test.png
Error: fontconfig: Didn't find expected font family. Perhaps URW Type 1 fonts need installing?
Error: fontconfig: Didn't find expected font family. Perhaps URW Type 1 fonts need installing?
$ echo $?
1


Running dot with -v suggests hardcoding might be the problem,
fontname: "Helvetica" resolved to: [internal hard-coded]

fontconfig itself knows where Helvetica is:

 $ fc-match Helvetica
 NimbusSans-Regular.otf: "Nimbus Sans" "Regular"

NimbusSans-Regular.otf is installed by fonts-urw-base35 at
/usr/share/fonts/opentype/urw-base35/NimbusSans-Regular.otf

So it looks like the error is coming from dot's hard-coded handling of
the font, not from fontconfig as such.

The bug is a problem since it causes the client programs like doxygen
to return an error, which causes packages to FTBFS.

Control: tags -1 -ftbfs
 Uh, I wanted to follow up on #1122412 but then missed. Graphviz is
now modularized.
Font handling is done by the libgvplugin-poppler module. You need to
add this to your build dependencies.
 With the above mentioned plugin installed, it will resolve the font:
fontname: "Helvetica" resolved to: (ps:pango  DejaVu Sans, )
(PangoCairoFcFont) "DejaVu Sans, Book"
/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf

Regards,
Laszlo/GCS

This bug is fixed now with graphviz 14.1.1-1

fenics-basix is able to build docs again.