With useflags ft2232 and ftdi set, it break with "ft2232 is x86 and ftdi is amd64, choose one or the other!" and only with ftdi "You enabled libftdi but not ft2232! libftdi is only used for ft2232, so this is meaningless!" and it will be compiled without ft2232 support. Reproducible: Always
It looks like this is intended behavior -- ftdi useflag is just not supported on amd64 because it is too much trouble. It would need a emul-linux-x86-libftd2xx package to get a 32-bit version compatible with other 32-bit stuff required for ft2232. Are you interested enough in ftdi support to build your own emul-linux package and try this approach in a local overlay?
It really doesn't seem intended, it actually seems like the ebuild is very much a mess wrt those particular USE flags. And if the USE flags are not supported on amd64 they should be masked properly by profiles.
Created attachment 178939 [details] get openocd compiled on amd64 with libftdi When i copiled it with USE="-ftdi ft2232" it was correctly compiled 32-bit. (there was one segfault in libftd2xx, but it is other problem). Hier my patch for ebuil, that get openocd compiled for me with libftdi, but it is quick and dirty.
libftd2xx now supports amd64, so the USE flags have been split in the ebuild
