flat_map (and flat_set) cannot adapt vector<bool> since it doesn't meet the sequence container requirements. We should reject vector<bool> at instantiation time with a clear error message citing [flat.map.overview]/7 (respectively [flat.set.overview]/7).

The visualizer for flat_map (currently on the feature/flat_map feature branch) has special cases that activate when both adapted containers are vector or deque. The vector visualization assumes the primary vector template and will therefore fail for flat_map<vector<bool>, meow> (I can't imagine anyone ever using this) and flat_map<meow, vector<bool>> (which should probably be a flat_set<meow>?). These are nowhere close to being important enough use cases to block merging the visualizer, but we should try to handle them properly for completeness.