Gentoo's Bugzilla –
Attachment 558632 Details for
Bug 673844app-emulation/virtualbox-6.0.0 - In file included from .../work/VirtualBox-6.0.0/src/VBox/Main/glue/VBoxLogRelCreate.cpp:22: .../work/VirtualBox-6.0.0/include/VBox/com/defs.h:286:10: fatal error: nsID.h: No such file or directory