[gentoo-user] Environment variables on package granularity

[Daniel Armbruster]

Hi gentoo-user,

is there a way to set environment variables on package/ebuild granularity? I'm
aware, that plenty of portage related environment variables are configurable by
means of the package.env feature
(https://wiki.gentoo.org/wiki//etc/portage/package.env). However, I didn't find
a way to set additional environment variables.

The actual reason, why I'm asking is the following: When compiling
app-emulation/qemu, package installation fails when calling the preprocessor.
Though, I'm able to manually solve the issue when setting the CPP environment
variable:

# export CPP="gcc -E"

before running emerge. Instead of running the command again and again i.e.
before every reinstallation of app-emulation/qemu, I'd like to set this
environment variable for the package once (in e.g. a configuration file) and
it's done for every future reinstallation.

Regards,
Daniel