Bug#1147678: mupen64plus-core: FTBFS with OpenCV 5.0

[Aron Xu]

Source: mupen64plus-core
Version: 2.6.0-3
Severity: important
Tags: ftbfs
User: opencv at packages.debian.org
Usertags: opencv5-transition
Control: affects -1 src:opencv
X-Debbugs-Cc: opencv at packages.debian.org, aron at debian.org

Dear maintainer,

Your package fails to build from source against opencv 5.0.0+dfsg-1~exp1,
currently in experimental.

OpenCV 5.0 renames its entire install tree from opencv4 to opencv5 and ships
no compatibility shims:

  * pkg-config: only /usr/lib/<triplet>/pkgconfig/opencv5.pc.  There is no
                opencv4.pc and no opencv.pc.
  * headers:    /usr/include/opencv5/opencv2/..., no /usr/include/opencv4.
  * cmake:      /usr/lib/<triplet>/cmake/opencv5/OpenCVConfig.cmake.  A bare
                find_package(OpenCV) still resolves, but a pinned version
                such as find_package(OpenCV 4.7) no longer matches.
  * modules:    libopencv-calib3d-dev is split into libopencv-calib-dev,
                libopencv-geometry-dev, libopencv-stereo-dev and
                libopencv-ptcloud-dev; libopencv-features2d-dev becomes
                libopencv-features-dev.  The CMake component names change
                with them (features2d -> features).
  * geometry:   the new geometry module is not only a piece of calib3d.  It
                also absorbs shape and contour functions that used to live
                in imgproc -- contourArea, arcLength, approxPolyDP,
                boundingRect, minAreaRect, convexHull and
                getPerspectiveTransform among them -- and opencv2/opencv.hpp
                does not pull in opencv2/geometry.hpp, so code that reached
                those through the umbrella header now needs an explicit
                include of opencv2/geometry.hpp.

mupen64plus-core fails because projects/unix/Makefile line 343 aborts
with "No OpenCV development libraries found!" as soon as OPENCV=1 is
set and pkg-config cannot resolve the opencv4 module; debian/patches/
Build-against-libopencv4.patch is what wires the OpenCV feature to
"pkg-config opencv4", and OpenCV 5.0 ships opencv5.pc instead. The
probe is not confined to the build step: it also fires when running
"make distclean", so the debian/rules clean invocation that
dpkg-buildpackage runs before dh_auto_build already aborts here, and
the build never even reaches the compile stage in this log. The
maintainer should update Build-against-libopencv4.patch to probe
"pkg-config --exists opencv5" (falling back to opencv4 for older
releases) and use the CFLAGS/LIBS it reports, rather than hardcoding
the opencv4 module name.

The same source builds fine in the same chroot against the OpenCV 4.10
packages currently in unstable, so this is specific to OpenCV 5.

The relevant part of the build log follows; the full log is attached.


  dpkg-source: info: skipping absent keyring
/usr/share/keyrings/debian-maintainers.pgp
  dpkg-source: info: extracting mupen64plus-core in
/build/reproducible-path/mupen64plus-core-2.6.0
  dpkg-source: info: unpacking mupen64plus-core_2.6.0.orig.tar.gz
  dpkg-source: info: unpacking mupen64plus-core_2.6.0-3.debian.tar.xz
  dpkg-source: info: using patch list from debian/patches/series
  dpkg-source: info: applying Use-font-from-fonts-dejavu-core.patch
  dpkg-source: info: applying
Disable-the-disassembler-of-the-recompiled-code.patch
  dpkg-source: info: applying Fix-spelling-errors.patch
  dpkg-source: info: applying Build-against-libopencv4.patch
  dpkg-source: info: applying
Don-t-print-recomp-interpreter-debug-info-when-debugger-i.patch
  dpkg-source: info: applying Fix-minizip-includes-for-zlib-v1.3.2-1173.patch

  Check disk space
  ----------------

  Sufficient free space for build

  User Environment
  ----------------

  APT_CONFIG=/var/lib/sbuild/apt.conf
  HOME=/sbuild-nonexistent
  LANG=en_US.UTF-8
  LC_ALL=C.UTF-8
  LOGNAME=sbuild
  PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
  SHELL=/bin/sh
  USER=sbuild

  dpkg-buildpackage
  -----------------

  Command: dpkg-buildpackage --sanitize-env -us -uc -b -j40
  dpkg-buildpackage: info: source package mupen64plus-core
  dpkg-buildpackage: info: source version 2.6.0-3
  dpkg-buildpackage: info: source distribution unstable
  dpkg-buildpackage: info: source changed by Sven Eckelmann <sven at narfation.org>
   dpkg-source --before-build .
  dpkg-buildpackage: info: host architecture amd64
   debian/rules clean
  dh clean --sourcedirectory="projects/unix"
     debian/rules override_dh_auto_clean
  make[1]: Entering directory '/build/reproducible-path/mupen64plus-core-2.6.0'
  make[2]: Entering directory
'/build/reproducible-path/mupen64plus-core-2.6.0/projects/unix'
  Makefile:343: *** No OpenCV development libraries found!.  Stop.
  make[2]: Leaving directory
'/build/reproducible-path/mupen64plus-core-2.6.0/projects/unix'
  make[1]: *** [debian/rules:31: override_dh_auto_clean] Error 25
  make[1]: Leaving directory '/build/reproducible-path/mupen64plus-core-2.6.0'
  make: *** [debian/rules:25: clean] Error 2
  dpkg-buildpackage: error: debian/rules clean subprocess failed with
exit status 2
  --------------------------------------------------------------------------------

Please close this bug if it turns out to be a collision with another ongoing
transition rather than an OpenCV 5 problem.

Thanks,
Aron
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