deps_src/eigen contained Eigen 3.3.7 from the ImageMap fork, which predates the Eigen::all placeholder (requires Eigen 3.4+). libigl in deps_src uses Eigen::all, causing build failures. Switch to find_package so the Eigen3::Eigen target resolves to the Eigen 5.0.1 installed by deps/ CMakeLists via CMAKE_PREFIX_PATH.
Eigen is a C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms.
For more information go to http://eigen.tuxfamily.org/.
THIS IS NOT THE COMPLETE EIGEN DISTRIBUTION. ONLY FILES NEEDED FOR COMPILING EIGEN INTO SLIC3R WERE PUT INTO THE SLIC3R SOURCE DISTRIBUTION. THIS DIRECTORY CONTAINS PIECES OF THE EIGEN 3.3.7 323c052e1731 SOURCE DISTRIBUTION.