Ohai, As part of the RAP project[1], a version of Gentoo Prefix that uses its own libc rather than relying on the host version, prefix needs some new profiles serving this variant. While this is entirely inconsequential for most packages, there are a handful of ebuilds that need to distinguish between the two prefix variants.
The chief difference between the two variants from the point of view of ebuilds is that in classic prefix, the host /usr/include is a valid include path (as it contains libc headers), whereas in RAP prefix it is not, and analogously so for library paths; this needs special handling for packages with build scripts that do their own exiting custom library searching, such as python, which needs to do certain prefix-specific hacks only for classic prefix and not for RAP. To this end, I'm introducing a globally masked USE flag, "prefix-guest", which is masked in the base profile and unmasked and forced in some prefix profiles; this flag indicates that /usr/include, /lib, and /usr/lib are valid paths despite being on a prefix system. This flag will be on in classic prefix, and off in prefix RAP. I will proceed in a week, assuming no complaints arise. -- Ruud [1] http://blogs.gentoo.org/news/2013/11/01/gentoo-monthly-newsletter-31-october-2013/#RAP
