Gentoo's Bugzilla –
Attachment 885683 Details for
Bug 925230dev-libs/libflatarray-0.4.0_pre20201009 fails to compile: main.cpp:172:43: error: no match for operator[] (operand types are LibFlatArray::soa_accessor<Cell, 32800, 32800, 1, 0> and LibFlatArray::coord<0, -2, -2>)