Certain ports hardcode which GCC version they want.
Ports That Hardcode GCC version
This is a common case – but it causes maintenance hassles.
| portname | hardcoding | comment |
| sysutils/uefi-edk2-bhyve-csm | 4.8 | |
| devel/xtensa-esp32-elf | 9 |
as of 20191220 the above ports as known to fail with newer versions of GCC. Contact MarkLinimon if you want to look at the errorlogs.
See also ObsoleteGCCVersions for tree-wide problems.