One more.... hb-ot-vorg-table.hh:96: error: ISO C++ says that these are ambiguous, even though the worst conversion for the first is better than the worst conversion for the second: hb-vector.hh:87: note: candidate 1: const Type& hb_vector_t<Type, PreallocedCount>::operator[](unsigned int) const [with Type = OT::VertOriginMetric, unsigned int PreallocedCount = 8u] hb-ot-vorg-table.hh:96: note: candidate 2: operator[](const T*, int) <built-in>