Subject: Re: bug#35313: Groff doc output is not reproducible

From: Simon Tournier <[email-masked]>
Date: Mon, 16 Jun 2025 12:29:19 +0200

Hi,

On Thu, 18 Apr 2019 at 10:05, Maxim Cournoyer <[email-masked]> wrote:
> The generated slide-demo.pdf file is at cause; diffoscope output
> attached.

Using Guix b17268b, I get:

--8<---------------cut here---------------start------------->8---
$ diff -r --no-dereference /gnu/store/b5f4qcdm8qkxyq2vm8jxjc1a5hsjlzlg-groff-1.22.4-doc{,-check}
Binary files /gnu/store/b5f4qcdm8qkxyq2vm8jxjc1a5hsjlzlg-groff-1.22.4-doc/share/doc/groff/examples/mom/typesetting.pdf and /gnu/store/b5f4qcdm8qkxyq2vm8jxjc1a5hsjlzlg-groff-1.22.4-doc-check/share/doc/groff/examples/mom/typesetting.pdf differ
--8<---------------cut here---------------end--------------->8---

And the PDF difference reads:

--8<---------------cut here---------------start------------->8---
$ diffoscope /gnu/store/b5f4qcdm8qkxyq2vm8jxjc1a5hsjlzlg-groff-1.22.4-doc{,-check}/share/doc/groff/examples/mom/typesetting.pdf
2025-06-16 10:26:41 W: diffoscope.comparators.xml: Vulnerable version of pyexpat detected; disabling comparison of XML documents. Install defusedxml or upgrade your pyexpat.
--- /gnu/store/b5f4qcdm8qkxyq2vm8jxjc1a5hsjlzlg-groff-1.22.4-doc/share/doc/groff/examples/mom/typesetting.pdf
+++ /gnu/store/b5f4qcdm8qkxyq2vm8jxjc1a5hsjlzlg-groff-1.22.4-doc-check/share/doc/groff/examples/mom/typesetting.pdf
│┄ 'dumppdf' not available in path. Falling back to binary comparison.
@@ -34200,1047 +34200,1047 @@
 00085970: 6f72 6d54 7970 6520 310a 2f4c 656e 6774  ormType 1./Lengt
 00085980: 6820 3332 0a2f 4e61 6d65 202f 584f 3435  h 32./Name /XO45
 00085990: 0a2f 5265 736f 7572 6365 7320 3c3c 202f  ./Resources << /
 000859a0: 5072 6f63 5365 7420 5b2f 5044 4620 2f54  ProcSet [/PDF /T
 000859b0: 6578 7420 2f49 6d61 6765 4220 2f49 6d61  ext /ImageB /Ima
 000859c0: 6765 4320 2f49 6d61 6765 4920 5d0a 2f58  geC /ImageI ]./X
 000859d0: 4f62 6a65 6374 203c 3c20 2f49 6d30 2034  Object << /Im0 4
-000859e0: 3920 3020 520a 3e3e 0a3e 3e0a 2f53 7562  9 0 R.>>.>>./Sub
+000859e0: 3620 3020 520a 3e3e 0a3e 3e0a 2f53 7562  6 0 R.>>.>>./Sub
 000859f0: 7479 7065 202f 466f 726d 0a2f 5479 7065  type /Form./Type

[...]

-00085aa0: 4c65 6e67 7468 2037 3832 360a 2f57 6964  Length 7826./Wid
-00085ab0: 7468 2038 310a 3e3e 0a73 7472 6561 6d0a  th 81.>>.stream.
-00085ac0: f585 ec84 fe85 da84 fb85 f884 fb85 fb86  ................
-00085ad0: fe82 fe7a fe6b fb65 fe58 fb66 fe6d fe7a  ...z.k.e.X.f.m.z

[...]

+00085aa0: 4c65 6e67 7468 2037 3832 360a 2f4e 616d  Length 7826./Nam
+00085ab0: 6520 2f49 6d30 0a2f 534d 6173 6b20 3439  e /Im0./SMask 49
+00085ac0: 2030 2052 0a2f 5375 6274 7970 6520 2f49   0 R./Subtype /I
+00085ad0: 6d61 6765 0a2f 5479 7065 202f 584f 626a  mage./Type /XObj

[...]
--8<---------------cut here---------------end--------------->8---

Cheers,
simon