GCC 8.4.0 built successfully on Haiku R1B2 x86_64 on Apr 17, 2021.
Fixes 210 bugs found with the GCC 8.3.0 official release.
Rebuilt today:
~/haikuports/sys-devel/gcc> ls -al ~/gcc_8.4.0
total 459192
drwxr-xr-x 1 user root 2048 Apr 18 19:36 .
drwxr-xr-x 1 user root 6144 Apr 18 19:36 ..
-rw-r--r-- 1 user root 393115083 Apr 18 19:36 gcc_debuginfo-8.4.0_2020_03_03-1-x86_64.hpkg
-rw-r--r-- 1 user root 12423212 Apr 18 19:36 gcc_fortran-8.4.0_2020_03_03-1-x86_64.hpkg
-rw-r--r-- 1 user root 2287921 Apr 18 19:36 gcc_syslibs_devel-8.4.0_2020_03_03-1-x86_64.hpkg
-rw-r--r-- 1 user root 1764644 Apr 18 19:36 gcc_syslibs-8.4.0_2020_03_03-1-x86_64.hpkg
-rw-r--r-- 1 user root 60588802 Apr 18 19:36 gcc-8.4.0_2020_03_03-1-x86_64.hpkg
~/haikuports/sys-devel/gcc> uname -a
Haiku shredder 1 hrev54154+123 Jan 4 2021 08:03 x86_64 x86_64 Haiku