We discussed this but I don't recall finding a good solution, so let's get things formal. The section on SRC_URI states that: > If a simple filename rather than a full URI is provided, the package manager > can only use mirrors to download the file. However, this isn't clear what kind of mirrors are used. Some developers are wrongly assuming this is implicit mirror://gentoo and are abusing it in ::gentoo. Worse than that, this isn't even the Portage behavior -- since Portage is only used user-defined GENTOO_MIRRORS, and if no GENTOO_MIRRORS are explicitly defined, it refuses to fetch. I think we should explicitly use something like 'user-defined mirrors' or 'site-defined mirrors'. Possibly add an explicit note that if no mirrors are defined on the system, the 'simple filename' case may result in fetch failure.
We need a terminology that also covers things like "The package's SRC_URI entries may not be mirrored, and mirrors should not be checked when fetching." I think that "user-defined mirrors" would sound strange in this context. Maybe "implicit" (local) vs "explicit" (third-party) mirrors?
I don't know. Please note that Portage is already using 'local' mirrors for mirrors that do not need to follow RESTRICT=fetch limitations. In other words, '${P}.tar.gz' with RESTRICT=fetch will be fetched from 'local' mirrors but not from GENTOO_MIRRORS.