Building libreoffice-6.2.5.2 with GCC 9.1.0-r1 results in an internal compiler error: Segmentation fault. This may be a blocker for 685044. Trying to build it with 8.3.0 as I'm writing this up. Build.log and emerge --info attached.
Created attachment 585348 [details] build.log
Created attachment 585350 [details] emerge --info
Please re-open with new build.log if you can reproduce with 6.2.8.2.
Andreas, I just confirmed that libreoffice-6.2.8.2 builds with gcc-9.2.0. All seems to be working now. Thanks!