0.3.1: Build error on EL9 (gcc 11.4)
[ 29s] [ 10%] Building CXX object ff/CMakeFiles/formfactor.dir/Make.cpp.o
[ 29s] cd /home/abuild/rpmbuild/BUILD/libformfactor-v0.3.1/build/redhat-linux-build/ff && /usr/bin/g++ -Dformfactor_EXPORTS -I/home/abuild/rpmbuild/BUILD/libformfactor-v0.3.1 -O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -march=x86-64-v2 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fPIC -pedantic -Wall -fno-omit-frame-pointer -O3 -std=gnu++2a -MD -MT ff/CMakeFiles/formfactor.dir/Make.cpp.o -MF CMakeFiles/formfactor.dir/Make.cpp.o.d -o CMakeFiles/formfactor.dir/Make.cpp.o -c /home/abuild/rpmbuild/BUILD/libformfactor-v0.3.1/ff/Make.cpp
[ 30s] /home/abuild/rpmbuild/BUILD/libformfactor-v0.3.1/ff/Face.cpp: In function 'R3 {anonymous}::precompute_normal(const std::vector<ff::Edge>&)':
[ 30s] /home/abuild/rpmbuild/BUILD/libformfactor-v0.3.1/ff/Face.cpp:98:19: error: 'using R3 = class Vec3<double>' {aka 'class Vec3<double>'} has no member named 'unit_or_null'
[ 30s] 98 | return result.unit_or_null();
[ 30s] | ^~~~~~~~~~~~