Reproducible: Always Actual Results: see attached
Created attachment 429162 [details] emerge --info
Created attachment 429164 [details] build.log
And, do you have glib.h file?
of course ./usr/include/glib-2.0/glib.h
I have this bug since 2013 https://forums.gentoo.org/viewtopic-t-984942-view-previous.html?sid=b6dda299d48a9f589bf0fcdb6f372308
emerging with 'glib' use flag allowed it to build succesfully. This time. Still, this seems like a bug?
fixed in 9.0