[xml/sgml-pkgs] Bug#847928: libxml2: sporadic "Unimplemented block at ../../xmlschemas.c:27279" errors

[Martin von Wittich]

Package: libxml2
Version: 2.9.1+dfsg1-5+deb8u3
Severity: normal
Tags: upstream

Dear Maintainer,

I'm trying to validate the grammar.xml of LanguageTool with xmlstarlet:

https://github.com/languagetool-org/languagetool/blob/master/languagetool-language-modules/de/src/main/resources/org/languagetool/rules/de/grammar.xml

This works, but xmlstarlet often prints "Unimplemented block" error
messages that seem to originate from libxml2:

www0.iserv.eu ~ # xmlstarlet val --err -s /opt/LanguageTool/org/languagetool/rules/rules.xsd /opt/LanguageTool/org/languagetool/rules/de/grammar.xml 2>&1 | tail
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
/opt/LanguageTool/org/languagetool/rules/de/grammar.xml:28343.17: Element 'rule': Character content other than whitespace is not allowed because the content type is 'element-only'.
/opt/LanguageTool/org/languagetool/rules/de/grammar.xml:28343.29: Element 'invalid-tag': This element is not expected. Expected is ( example ).
/opt/LanguageTool/org/languagetool/rules/de/grammar.xml - invalid

I've reduced the grammar.xml to a minimal working example that still
triggers the issue, and I'll attach it along with the necessary *.xsd
files so the issue can be reproduced. The error doesn't occur every
time, but is still easily reproducable by running the command multiple
times:

www0.iserv.eu ~ # xmlstarlet val -q --err -s rules.xsd grammar.xml
www0.iserv.eu ~ # xmlstarlet val -q --err -s rules.xsd grammar.xml
www0.iserv.eu ~ # xmlstarlet val -q --err -s rules.xsd grammar.xml
www0.iserv.eu ~ # xmlstarlet val -q --err -s rules.xsd grammar.xml
www0.iserv.eu ~ # xmlstarlet val -q --err -s rules.xsd grammar.xml
www0.iserv.eu ~ # xmlstarlet val -q --err -s rules.xsd grammar.xml
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
www0.iserv.eu ~ # xmlstarlet val -q --err -s rules.xsd grammar.xml
www0.iserv.eu ~ # xmlstarlet val -q --err -s rules.xsd grammar.xml
www0.iserv.eu ~ # xmlstarlet val -q --err -s rules.xsd grammar.xml
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279
Unimplemented block at ../../xmlschemas.c:27279

I believe the bug corresponds to this upsteam bug report:
https://bugzilla.gnome.org/show_bug.cgi?id=723607

-- System Information:
Debian Release: 8.6
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.16.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages libxml2 depends on:
ii  libc6              2.19-18+deb8u6
ii  liblzma5           5.1.1alpha+20120614-2+b3
ii  multiarch-support  2.19-18+deb8u6
ii  zlib1g             1:1.2.8.dfsg-2+b1

Versions of packages libxml2 recommends:
ii  xml-core  0.13+nmu2

libxml2 suggests no packages.

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