On 3/27/2020 1:16 PM, Johannes Hielscher wrote:
You are 100% right. That's why I did not call it a bug in the first
place, because everyone does their job right, and nothing has to be
fixed. I have found this out the hard way, and just wanted to leave
it somewhere: it might be helpful for someone else scratching their
heads about the sparse evidence of pdftex being less pedantic about
buggy PDFs than luatex.
That's indeed the danger of programs being tolerant. Mupdf. qpdf, xpdf
all have some (different) strategies in loading files, sometimes they
ignore the xref, sometimes they fix and recover, etc. The problem with
such heuristics is that bad pdf stays around (if one already knows what
gets 'ignored'. There are also similar tricks for dealing with bad fonts
cq. font embedding and annotations and such. So one never really knows
if the opdf file one makes is ok (also because validators don't check
everything).
As already stated, no mercy for people who have their PDF encoding/
xref tables not under control, and even a bit less in luatex (which
is not necessarily a bad thing!). Fall-out wrt. hard to detect edge
cases in high-level environments included.
Indeed. The most one can expect is a message that something is wrong. Of
course there can be real bugs in the inclusion, which then need to be
solved, but we've tested with many thousands of files so it looks ok so
far.
Hans
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