I'm not raising priority because I'm not 100% certain that the failure is a
mistake in the packaging or a mismatch in our build environment.

If it is a problem on our side, any hint would be appreciated.

During a build of openjdk-21 in Trixie, I encountered the following error:

dh_clean
 debian/rules binary
jtreg_version="$(dpkg-query -f '${Version}\n' -W jtreg)"; \
if ! dpkg --compare-versions 7.3.1+1~ le $jtreg_version; then \
  echo "Error: testsuite requires jtreg 7.3.1+1~ but $jtreg_version is
installed"; \
  echo "Please update the jtreg dependency and regenerate debian/control"; \
  false; \
fi
dpkg: error: --compare-versions takes three arguments: <version> <relation>
<version>

Installing jtreg7 (from Build-Depends) on my system and running

dpkg-query -f '${Version}\n' -W jtreg

Indeed results in an empty string.
The query for the jtreg version happens here:
https://salsa.debian.org/openjdk-team/openjdk/-/blob/openjdk-21/debian/rules#L1145

I suspect that
https://salsa.debian.org/openjdk-team/openjdk/-/blob/openjdk-21/debian/rules#L164
needs an update. Though I honestly am not sure why it assigned jtreg_pkg to
be "jtreg" and not "jtreg7"

I'm somewhat confused by this though. In the build-chroot, with lsb-release
installed, I get:

# lsb_release --codename --short
sid
# # lsb_release --id --short
Debian

as I expected, since our rebuilds found emulating sid (though with the
packages from testing) to be the most reliable path to successful builds.
Here is the complete output from the dpkg-buildpackage run:

Command: dpkg-buildpackage --sanitize-env -us -uc -b -rfakeroot
dpkg-buildpackage: info: source package openjdk-21
dpkg-buildpackage: info: source version 21.0.6+7-1
dpkg-buildpackage: info: source distribution unstable
dpkg-buildpackage: info: source changed by Matthias Klose <doko@ubuntu.com>
 dpkg-source --before-build .
dpkg-buildpackage: info: host architecture amd64
 debian/rules clean
dh_testdir
dh_testroot
dh_prep
for f in debian/*.in; do \
  f2=$(echo $f | sed 's/JB/openjdk-21/;s/\.in$//'); \
  case "$f2" in debian/control|debian/watch) continue; esac; \
  rm -f $f2; \
done
rm -f debian/*.install debian/*.links debian/*.debhelper.log
dh_testdir
dh_testroot
rm -rf stamps build build-* jtreg-test-output
rm -rf autom4te.cache
rm -f bin/{jtreg.tmwrc,my-jtreg-run,my-xvfb-run,auto*,ifnames}
rm -f buildwatch.pid
rm -f config.log configure.log
dh_clean
 debian/rules binary
jtreg_version="$(dpkg-query -f '${Version}\n' -W jtreg)"; \
if ! dpkg --compare-versions 7.3.1+1~ le $jtreg_version; then \
  echo "Error: testsuite requires jtreg 7.3.1+1~ but $jtreg_version is
installed"; \
  echo "Please update the jtreg dependency and regenerate debian/control"; \
  false; \
fi
dpkg: error: --compare-versions takes three arguments: <version> <relation>
<version>

Type dpkg --help for help about installing and deinstalling packages [*];
Use 'apt' or 'aptitude' for user-friendly package management;
Type dpkg -Dhelp for a list of dpkg debug flag values;
Type dpkg --force-help for a list of forcing options;
Type dpkg-deb --help for help about manipulating *.deb files;

Options marked [*] produce a lot of output - pipe it through 'less' or
'more' !
Error: testsuite requires jtreg 7.3.1+1~ but  is installed
Please update the jtreg dependency and regenerate debian/control
make: *** [debian/rules:1145: pre-build] Error 1
dpkg-buildpackage: error: debian/rules binary subprocess returned exit
status 2
--------------------------------------------------------------------------------
Build finished at 2025-02-14T14:41:29Z

All in all, I wonder why you check the version again in debian/rules when
debian/control already has the proper dependencies?

Kind regards,
Sven

Note; For a reason I don't see, the Debian build happened to have codename
`trixie` - despite the build supposedly having been uploaded to unstable. -
In other words, it didn't see itself as building on `sid`, it saw itself
being built on `trixie`.

Anyhow, the solution to this is rather simple: Remove `sid` from line 164
of debian/rules, similar to how it was done in
https://salsa.debian.org/openjdk-team/openjdk/-/commit/c257671660f03ef6d9c394adfa762d9fcc59db86
for openjdk-22 (and carried forward to openjdk-23, -24 and onwards, I
assume).

Consider pulling the same change into openjdk-21?

Cheers,
Sven

can't reproduce, works fine for me on testing and on unstable.

The difference is in this (from the i386 build in unstable)

========== stamps/configure ==========
mkdir -p bin
command -v autoconf
/usr/bin/autoconf
/bin/uname -a
Linux sbuild 6.1.0-33-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.133-1
(2025-04-10) i686 GNU/Linux
lsb_release -a
Distributor ID: Debian
Description: Debian GNU/Linux trixie/sid
Release: n/a
Codename: trixie

In our builds, the last line would be:
Codename: sid

The other openjdk-2* packages have a different comparison in
debian/rules line 165 (well, or close to that line) to select the
jtreg package to compare to, which doesn't include `sid` but only
bookworm and bullseye - which makes them select jtreg7 to query dpkg
for later on - and the builds in Debian itself apparently also
correctly select jtreg7 because the codename is (somewhat
incorrectly?) set to `trixie`. I'd appreciate if you could remove sid
from that line in the openjdk-21 package. To Debian builds, it
obviously doesn't matter (because the codename in unstable builds is
set to trixie), but for anyone attempting a build on a system that has
Codename:sid, it would.

We believe that the bug you reported is fixed in the latest version of
openjdk-21, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1096195@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Vladimir Petko <vladimir.petko@canonical.com> (supplier of updated openjdk-21 package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Wed, 16 Sep 2026 08:41:53 +1200
Source: openjdk-21
Built-For-Profiles: derivative.ubuntu noudeb
Architecture: source
Version: 21.0.13~6ea-1
Distribution: unstable
Urgency: medium
Maintainer: OpenJDK Team <openjdk-21@packages.debian.org>
Changed-By: Vladimir Petko <vladimir.petko@canonical.com>
Closes: 1096195
Launchpad-Bugs-Fixed: 2095441
Changes:
 openjdk-21 (21.0.13~6ea-1) unstable; urgency=medium
 .
   * OpenJDK 21.0.13 early access, build 6.
   * d/JB-{jre-headless,jre-zero,testsuport}.overrides.in: suppress
     specific-address-in-shared-library for i386 (JDK-6454213).
   * d/rules: disable tree-slp-vectorize for Ubuntu S390x builds (LP:
     #2095441). Add workaround for Launchpad C2 crash.
   * d/p/{jdk-8334502-proposed.patch,debian/patches/jdk-8359735.patch}:
     Drop patches applied upstream.
   * d/rules: Require jtreg8 package (Closes: #1096195).
   * Regenerate control files.
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