xdvipdfmx fails with some regtests (“Invalid object”)

[Valentin Villenave]

Hey everybody,
`make doc’ has been broken for nearly a week on my system (even with a
clean git clone), with the following error:

Making input/regression/out-www/collated-files.list < 1368 files
Making input/regression/out-www/collated-files.texi < tely
Making input/regression/out-www/collated-files.pdf < texi
Command: cd ./out-www; texi2pdf --batch -q -I input/regression \
  -o collated-files.tmp.pdf collated-files.texi < /dev/null
xdvipdfmx:fatal: typecheck: Invalid object type: -1 7 (line 2161)
No output PDF file written.
/usr/bin/texi2dvi: scripts/build/xetex-with-options.sh exited with bad
status, quitting.

The "line 2161" doesn’t vary; it actually refers to xdvipdfmx itself
and not to our source files:
https://duckduckgo.com/?q="line+2161"+"xdvipdfmx";

This is on a Fedora system with xdvipdfmx 20190225 and gs 9.52.

It took me hours to track it down to the exact regtests that trigger
this; this happens iff any of the following files is found in
input/regression:

├── header-score-multiple.ly
├── header-score-reordered.ly
├── header-toplevel-multiple.ly
├── markup-cyclic-reference.ly
├── skiptypesetting-all-true.ly
├── tag-filter.ly
├── tag-group.ly
└── tag-multiple.ly

If these files have anything in common (and that isn’t shared by any
of the other regtests), I don’t have a clue as to what it might be.
Meanwhile, I’ll have to remove these regtests of all my git branches
if I have any chance of being able to `make doc’ again (actually
there’s another error I need to track down, but it seems unrelated;
I’ll open another thread about it).

Cheers,
-- V.