This patch adds isDirectlyDerivedFrom AST-matcher which is similar to isDerivedFrom but only matches against direct base classes.
I think these tests are ~enough, given the implementation.
So, I did like the more exhaustive doc, I thought you'd move it to the code so it also shows up in the generated doc page :) (sorry for not being clearer here)
If you say /*Directly=*/false, you should
I'm fine with doing it in a follow-up commit, but it should be done (it shouldn't assert on invalid input, only on thought-to-be impossible situations, generally speaking).
You should register this in Registry.cpp as an overload, like we do for isDerivedFrom() and isSameOrDerivedFrom().