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I wrote that very thing a year or so ago for the purpose of testing if a base pointer type can be statically downcast to a derived type.

My problem exactly !

I should warn you that this isn't quite enough information to test for static downcastability in all cases. Take the following example: struct b1 {}; struct b2 : b1 {}; struct b3 : virtual b2 {}; Here, b1 is not a virtual base of b3, but a downcast from b1* to b3* is still impossible. I don't believe there is any way to test for this case without compiler assistance. Testing for a virtual base happened to be good enough for us though, so we went with it; it may well be enough for your needs too.