Dear maintainer,

During a test rebuild for CMake 4, orocos-kdl failed to rebuild.

Log Summary:
-------------------------------------------------------------------------------
[...]
	cd .pybuild/cpython3_3.13/build && PKG_CONFIG=/usr/bin/pkg-config cmake -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=None -DCMAKE_INSTALL_SYSCONFDIR=/etc -DCMAKE_INSTALL_LOCALSTATEDIR=/var -DCMAKE_EXPORT_NO_PACKAGE_REGISTRY=ON -DCMAKE_FIND_USE_PACKAGE_REGISTRY=OFF -DCMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY=ON -DFETCHCONTENT_FULLY_DISCONNECTED=ON -DCMAKE_INSTALL_RUNSTATEDIR=/run -DCMAKE_SKIP_INSTALL_ALL_DEPENDENCY=ON "-GUnix Makefiles" -DCMAKE_VERBOSE_MAKEFILE=ON -DCMAKE_INSTALL_LIBDIR=lib/aarch64-linux-gnu -DPYTHON_EXECUTABLE:FILEPATH=/usr/bin/python3.13 -DPYTHON_LIBRARY:FILEPATH=/usr/lib/python3.13/config-3.13-aarch64-linux-gnu/libpython3.13.so -DPYTHON_INCLUDE_DIR:PATH=/usr/include/python3.13 -DPython_EXECUTABLE=/usr/bin/python3.13 -DPython_LIBRARY=/usr/lib/python3.13/config-3.13-aarch64-linux-gnu/libpython3.13.so -DPython_INCLUDE_DIR=/usr/include/python3.13 -DPython3_EXECUTABLE=/usr/bin/python3.13 -DPython3_LIBRARY=/usr/lib/python3.13/config-3.13-aarch64-linux-gnu/libpython3.13.so -DPython3_INCLUDE_DIR=/usr/include/python3.13 -DPYVER=3.13 ../../..
CMake Error at CMakeLists.txt:1 (CMAKE_MINIMUM_REQUIRED):
  Compatibility with CMake < 3.5 has been removed from CMake.

  Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
  to tell CMake that the project requires at least <min> but has been updated
  to work with policies introduced by <max> or earlier.

  Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.
-------------------------------------------------------------------------------

The above is just how the build ends and not necessarily the most relevant part.
If required, the full build log is available here (for the next 30 days):
https://debusine.debian.net/artifact/2406425/

The most likely cause of build failures is the removed backwards compatibility for
CMake versions earlier than 3.5. You can find additional information in my
debian-devel announcement:

https://lists.debian.org/debian-devel/2025/04/msg00310.html

About the archive rebuild: The build was made on debusine.debian.net,
using sbuild.

You can find the build task here:
https://debusine.debian.net/work-request/154375/

If this is really a bug in one of the build-depends, please use
reassign and affects, so that this is still visible in the BTS web
page for this package.

Thanks,
Timo

I have downgraded the bug to non-RC severity temporarily and reverted
CMake in unstable to version 3.31.6. I plan to re-upgrade in about a
month's time. I realize that despite my April announcement, the upload
to unstable came rather surprising, and I don't want to cause
unnecessary pain.

Also, the build log URL has an unfortunate mistake. The correct URL
should include the workspace, i.e.,

https://debusine.debian.net/debian/developers/artifact/XXXX

CMake 4 will also be available in experimental again, so it can be
used to verify that the bug is fixed.

Cheers
Timo