[eliasmacpherson]

Ah, well I guess I did take it as an example of something that was incompatible. It served well enough as a vehicle to drive the conversation forwards.

The iterator invalidation occurs when push_back(), insert() or erase() are called, presumably among others, so you'd also want to overload the iterator increment and decrement operators too (oh!, not to forget end(), or rend() if you are going the other way...). I'm not sure what operators and methods would be called on passing to an std::algorithm like std::find or std::sort. Most likely the only way to find out for certain would be to make everything inaccessible and replace piecemeal until the compiler was happy to run to completion.

I'd want to take a closer look where it's instantiated, but if all the uses are 'auto', well let's just say I'd be unhappy to say the least.