Since Gentoo Portage introduced the package specific configuration in /etc/portage there was one thing I always missed: specifying environment variables per package. Some environment variables you might want to specify per package are CFLAGS, CXXFLAGS and FEATURES. Especially when you do debugging, some packages should not be stripped, which is the perfect use case for the FEATURES environment variable. While specifying USE-flags and keywords per package, the rest is not that easy. Christian Hoffmann dropped me a link to this mail: the tip there works fine. I’ve played around with it and implemented it slightly differently: first, I would like to be informed which environment files are read and second I changed the resolution order so that the specific configuration inherits from the more generic. So this is what my /etc/portage/bashrc looks like now:

For dev-lang/php-5.2.6-r3 I can use three different files to customize the build environment: /etc/portage/env/dev-lang/php.env would apply for all PHP ebuilds, /etc/portage/env/dev-lang/php-5.2.6.env for all revision of the ebuild for 5.2.6 and /etc/portage/env/dev-lang/php-5.2.6-r2.env for the exact ebuild. My /etc/portage/env/dev-lang/php.env file now looks like this to disable stripping the binaries after emerging them and keeping the working directory for better backtraces: