> [...] so I assume even with GCC support removed, you can still build FreeBSD, if you insist, with an external copy of modern GCC.
Indeed- "external toolchain" includes gcc6[0] and gcc9[1] ports that can be used specifically for building the FreeBSD base system. These are mostly easy to use, install the flavor for whatever architecture you're building and specify CROSS_TOOLCHAIN=<arch>-gcc6 when you build. More/better/complete information (and examples!) at [2].
lapack, for example, has USES=fortran[1]. That invokes Uses/fortran.mk[2] and accepts the ports-default fortran compiler, FORTRAN_DEFAULT, which is definedin bsd.default-versions.mk[3] as gfortran (GCC).
Nothing changes here- this is solely about removing GCC 4.2 from the base/ repository; ports are almost entirely unaffected, and the GCC ecosystem in ports is fairly healthy.
Indeed- "external toolchain" includes gcc6[0] and gcc9[1] ports that can be used specifically for building the FreeBSD base system. These are mostly easy to use, install the flavor for whatever architecture you're building and specify CROSS_TOOLCHAIN=<arch>-gcc6 when you build. More/better/complete information (and examples!) at [2].
[0] https://www.freshports.org/devel/freebsd-gcc6
[1] https://www.freshports.org/devel/freebsd-gcc9
[2] https://wiki.freebsd.org/ExternalToolchain