Variant in phobos doesn't work well with being const, toHash and opEquals for example are not marked as const methods. I have tried to work around it with careful casting, but it is too unsafe and just too complex for something that is supposed to make life easier.
Does anybody know if this is a temporary problem with variant itself or related to other bugs or limitations? Should I file a bug report for this? I could only find this: http://d.puremagic.com/issues/show_bug.cgi?id=3795