Hello, On 1327ec822fa6dd396e979efd8d4e1f7479f1d5b3 (current master), OpenFOAM 4.1 fails to build (from ): --8<---------------cut here---------------start------------->8--- g++ -std=c++0x -m64 -Dlinux64 -DWM_ARCH_OPTION=64 -DWM_DP -DWM_LABEL_SIZE=32 -Wall -Wextra -Wold-style-cast -Wnon-virtual-dtor -Wno-unused-parameter -Wno-invalid-offsetof -O3 -DNoRepository -ftemplate-depth-100 -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/finiteVolume/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/dynamicMesh/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/meshTools/lnInclude -IlnInclude -I. -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/OpenFOAM/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/OSspecific/POSIX/lnInclude -fPIC -c moveMesh.C -o /tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/platforms/linux64GccDPInt32Opt/applications/utilities/mesh/manipulation/moveMesh/moveMesh.o In file included from /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/IO/Color.h:21:0, from /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/IO/io.h:30, from /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/Needs_parens_as_product.h:20, from /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/number_type_basic.h:45, from /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/basic.h:33, from /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/Delaunay_triangulation_3.h:22, from lnInclude/CGALTriangulation3DKernel.H:36, from lnInclude/CGALTriangulation3Ddefs.H:41, from DelaunayMeshTools/DelaunayMeshTools.H:45, from DelaunayMeshTools/DelaunayMeshTools.C:26: /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/array.h:72:44: error: ?std::index_sequence? has not been declared make_filled_array_aux(const T& value, std::index_sequence) ^~~~~~~~~~~~~~ /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/array.h:72:58: error: expected ?,? or ?...? before ?) ^ /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/array.h: In function ?constexpr std::array CGAL::make_filled_array(const T&)?: /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/array.h:80:44: error: ?make_index_sequence? is not a member of ?std? return make_filled_array_aux(value, std::make_index_sequence()); ^~~~~~~~~~~~~~~~~~~ /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/array.h:80:67: error: expected primary-expression before ?)? token return make_filled_array_aux(value, std::make_index_sequence()); ^ In file included from /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/double.h:22:0, from /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/number_type_basic.h:51, from /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/basic.h:33, from /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/Delaunay_triangulation_3.h:22, from lnInclude/CGALTriangulation3DKernel.H:36, from lnInclude/CGALTriangulation3Ddefs.H:41, from DelaunayMeshTools/DelaunayMeshTools.H:45, from DelaunayMeshTools/DelaunayMeshTools.C:26: /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/number_utils.h: At global scope: /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/number_utils.h:319:10: error: expected primary-expression before ?auto? decltype(auto) approximate_sqrt(const NT& nt) ^~~~ /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/number_utils.h:319:10: error: expected ?)? before ?auto? /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/number_utils.h:319:10: error: expected primary-expression before ?auto? /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/number_utils.h:319:10: error: expected primary-expression before ?auto? /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/number_utils.h:319:10: error: expected primary-expression before ?auto? /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/number_utils.h:319:10: error: expected primary-expression before ?auto? /gnu/store/86p0n4k4ahkc0kg7n4qz1mfg02czhyhd-cgal-5.2.2/include/CGAL/number_utils.h:319:1: error: expected unqualified-id before ?decltype? decltype(auto) approximate_sqrt(const NT& nt) ^~~~~~~~ --8<---------------cut here---------------end--------------->8--- (It hasn’t been touched since 2017, so it might have been failing for a long time.) I naively tried building against CGAL 4.x (patch below) but that failed elsewhere: --8<---------------cut here---------------start------------->8--- g++ -std=c++0x -m64 -Dlinux64 -DWM_ARCH_OPTION=64 -DWM_DP -DWM_LABEL_SIZE=32 -Wall -Wextra -Wold-style-cast -Wnon-virtual-dtor -Wno-unused-parameter -Wno-invalid-offsetof -O3 -DNoRepository -ftemplate-depth-100 -frounding-math -DNDEBUG -I/gnu/store/hwrhh7icnj2rsr208szblzys2j91gqq3-cgal-4.14.2/include -I/gnu/store/5jf395qa3v4amdi60850rz2a15zlsrza-mpfr-4.0.2/include -I/gnu/store/35afkywncrr5xsb4cxcljf6rpjcb7f61-gmp-6.2.0/include -I/gnu/store/vp2s1nxsc9vvc1ix66xpbf041f8nacxr-boost-1.72.0/include -I/usr/include -Wno-old-style-cast -Wno-unused-local-typedefs -Wno-array-bounds -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/applications/utilities/mesh/generation/extrude2DMesh/extrude2DMesh/lnInclude -I../conformalVoronoi2DMesh/lnInclude -I../conformalVoronoiMesh/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/parallel/decompose/decompositionMethods/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/finiteVolume/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/meshTools/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/surfMesh/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/edgeMesh/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/dynamicMesh/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/mesh/extrudeModel/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/sampling/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/triSurface/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/fileFormats/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/mesh/snappyHexMesh/lnInclude -IlnInclude -I. -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/OpenFOAM/lnInclude -I/tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/src/OSspecific/POSIX/lnInclude -fPIC -c foamyQuadMesh.C -o /tmp/guix-build-openfoam-4.1.drv-0/OpenFOAM-4.1/platforms/linux64GccDPInt32Opt/applications/utilities/mesh/generation/foamyMesh/foamyQuadMesh/foamyQuadMesh.o In file included from insertSurfaceNearPointPairs.C:26:0: CV2D.H:352:51: error: ‘point’ does not name a type inline const point2D& toPoint2D(const point&) const; ^~~~~ CV2D.H:354:20: error: ‘point’ does not name a type inline point toPoint3D(const point2D&) const; ^~~~~ --8<---------------cut here---------------end--------------->8--- It would probably be best to upgrade, but that’s an intimidating piece of software and it takes a lot of CPU time to build. Thoughts? Ludo’.