A question like this has come up before with respect to being able to identify threads.

If you only want to name threads then you can use the thread::get_id() function. The thread::id value provides a comparison operator so that you can use it in, for example a std::map<thread::id,std::string> to provide a mapping between boost ids and something more user-friendly.

Yes, this doesn't necessarily fit very well with a debugger but for lots of applications this is enough, to be able associate a "name" with a thread.

I understand why you want to be able to get to the "raw" id, and it would, in all probability, be a change that doesn't break anyone, but it does give people the temptation to break portability without thinking about other solutions that are open to them.

I'm on the fence basically. I wouldn't suggest breaking a hole in the interface to let you peek at the OS id but I also wouldn't spend too much energy arguing against it.