Bugzilla Bug 228907

portage apparently is removing CROSSCOMPILE_OPTS from the environment thus
breaking any cross-compiles of glibc

for example, adding this to any ebuild:
pkg_setup() { die $CROSSCOMPILE_OPTS ; }

and then emerging it by doing:
CROSSCOMPILE_OPTS="headers-only" emerge ...

shows that the variable is empty when it clearly should not be

the related command "use crosscompile_opts_headers-only" also fails

The problem is that CROSSCOMPILE_OPTS is in USE_EXPAND yet glibc doesn't have
crosscompile_opts_headers-only in IUSE. In order to stop
CROSSCOMPILE_OPTS="headers-only" from being filtered, you can remove
CROSSCOMPILE_OPTS from USE_EXPAND or else add crosscompile_opts_headers-only to
IUSE.

it's not in IUSE on purpose: these are internal variables that the user should
know nothing about

It sounds like maybe CROSSCOMPILE_OPTS doesn't really fit well in USE_EXPAND
then...

If you really need to keep CROSSCOMPILE_OPTS in USE_EXPAND for some reason, you
can just add the relevant flags to IUSE. Since CROSSCOMPILE is also in
USE_EXPAND_HIDDEN, users won't see those flags in emerge output.

If CROSSCOMPILE_OPTS must be in USE_EXPAND and you absolutely refuse to add the
relevant flags to IUSE, we have another option. We can add an exemption for
USE_EXPAND_HIDDEN variables that exempts them from the IUSE filtering behavior.

i didnt opt for the IUSE_EXPAND cruft, someone else did.  if adding the stuff
to IUSE fixes things and it wont show up in -pv output, that's fine.  of course
Bug 133327 still needs to be implemented, but until then ...

thanks for researching + fix