Ian Stakenvicius wrote:
Technically it could, but the issue here would be what you are going to do with a has_version check on an IUSE_RUNTIME dep -- the package should do filesystem-identical installs no matter what status of IUSE_RUNTIME flags, so whatever one would do with a has_version check would have to not change any part of the build or installation.
In principle it would be used for more or less the same thing as it would in a dependency, i.e. check whether the runtime-only dependencies for that feature are satisfied - the difference being that the package can specify arbitrary if-yes and if-no behaviours, rather than just "fail the dependency resolution" or not. (Modulo the problem being discussed in this subthread, that a "no" answer isn't reliable.)
For example, some tool used during the build might have a "slow" mode that always works, and a "fast" mode that requires some other program to be installed and that has to be requested explicitly. So the package that uses the tool might want to do something like
src_compile() { if has_version dev-util/buildtool[fast]; then buildtool --fast else buildtool fi }