Dear Maintainer, your package depends on libeigen3-dev. The upstream released a new major version of this mathematical library, 5.0.0. Some basic information about new features and changes in this version can be found here: https://libeigen.gitlab.io/releases/5.0/ This is a major version change and may require code changes in packages depending on eigen3. The key breaking changes include: - Minimum required C++ standard is now C++14 - Changes in the build system integration - Some API name changes fcl FTBFS with libeigen3-dev 5.0.1. The full build log is available at: https://debusine.debian.net/debian/developers-gladk-eigen3/artifact/3755617/raw/fcl_0.7.0-3_amd64-2026-05-08T08:27:49Z.build Here is the most probably relevant part of the failing build log: =========================================== [ 1%] Building CXX object src/CMakeFiles/fcl.dir/broadphase/broadphase_bruteforce.cpp.o cd /build/reproducible-path/fcl-0.7.0/obj-x86_64-linux-gnu/src && /usr/bin/c++ -Dfcl_EXPORTS -I/build/reproducible-path/fcl-0.7.0/obj-x86_64-linux-gnu/include -I/build/reproducible-path/fcl-0.7.0/include -isystem /usr/include/eigen3 -g -O2 -ffile-prefix-map=/build/reproducible-path/fcl-0.7.0=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -std=c++11 -W -Wall -Wextra -Wpedantic -fPIC -fvisibility=hidden -MD -MT src/CMakeFiles/fcl.dir/broadphase/broadphase_bruteforce.cpp.o -MF CMakeFiles/fcl.dir/broadphase/broadphase_bruteforce.cpp.o.d -o CMakeFiles/fcl.dir/broadphase/broadphase_bruteforce.cpp.o -c /build/reproducible-path/fcl-0.7.0/src/broadphase/broadphase_bruteforce.cpp In file included from /usr/include/eigen3/Eigen/Core:22, from /usr/include/eigen3/Eigen/Dense:1, from /build/reproducible-path/fcl-0.7.0/include/fcl/common/types.h:46, from /build/reproducible-path/fcl-0.7.0/include/fcl/math/bv/AABB.h:41, from /build/reproducible-path/fcl-0.7.0/include/fcl/geometry/collision_geometry.h:43, from /build/reproducible-path/fcl-0.7.0/include/fcl/narrowphase/collision_object.h:43, from /build/reproducible-path/fcl-0.7.0/include/fcl/broadphase/broadphase_collision_manager.h:44, from /build/reproducible-path/fcl-0.7.0/include/fcl/broadphase/broadphase_SSaP.h:42, from /build/reproducible-path/fcl-0.7.0/include/fcl/broadphase/broadphase_SSaP-inl.h:41, from /build/reproducible-path/fcl-0.7.0/src/broadphase/broadphase_SSaP.cpp:38: /usr/include/eigen3/Eigen/src/Core/util/Macros.h:749:2: error: #error Eigen requires at least c++14 support. 749 | #error Eigen requires at least c++14 support. | ^~~~~ In file included from /usr/include/eigen3/Eigen/Core:22, from /usr/include/eigen3/Eigen/Dense:1, from /build/reproducible-path/fcl-0.7.0/include/fcl/common/types.h:46, from /build/reproducible-path/fcl-0.7.0/include/fcl/math/bv/AABB.h:41, from /build/reproducible-path/fcl-0.7.0/include/fcl/geometry/collision_geometry.h:43, from /build/reproducible-path/fcl-0.7.0/include/fcl/narrowphase/collision_object.h:43, from /build/reproducible-path/fcl-0.7.0/include/fcl/broadphase/broadphase_collision_manager.h:44, from /build/reproducible-path/fcl-0.7.0/include/fcl/broadphase/broadphase_bruteforce.h:42, from /build/reproducible-path/fcl-0.7.0/include/fcl/broadphase/broadphase_bruteforce-inl.h:41, from /build/reproducible-path/fcl-0.7.0/src/broadphase/broadphase_bruteforce.cpp:38: /usr/include/eigen3/Eigen/src/Core/util/Macros.h:749:2: error: #error Eigen requires at least c++14 support. 749 | #error Eigen requires at least c++14 support. | ^~~~~ =========================================== libeigen3-dev_5.0.1-1 is available in experimental. When this package version lands into unstable (probably at the beginning of June 2026), this bug will be increased in severity to serious. Thanks, Anton