Perhaps this suggestion has come up before, it seems so obvious, but my bugzilla searches were timing out, and I was unsure about narrowing down the returned bugs, given emerge --info results, so attempts to check weren't working. Looking thru /var/db/pkg, it appears portage tracks all manner of stuff, but not the gcc version used to build the package. That would be /very/ handy information to have at times, particularly when attempting to rebuild old-gcc build packages (thus avoiding an emerge --emptytree system, when much of it has already been compiled with the newer gcc), and when tracking down certain package interaction bugs. Note that this information will need to be included in binpkgs as well, and portage will need to track /that/, not simply what version of gcc was configured at the time of merge. Still, even the latter would be useful, for those of us with FEATURES=buildpkg, altho it wouldn't necessarily always be accurate. The info could be tracked either as a new file, GCCVERSION or some such, or simply added to the environment before it's saved, as an appropriately labeled variable.
Well, I don't think a feature like this should be gcc specific. There are lots of different languages/compilers used for various types of ebuilds. I think it should be the ebuild's job to tell portage what kind of compiler it used.
Adding arbitrary keys to the VDB is not currently feasable, and that is essentially what you are asking for.
*** Bug 187268 has been marked as a duplicate of this bug. ***
