[boost] [filesystem] what happened to default_name_check()?

I'm in the process of porting bcp to Filesystem V3, as the change of default to V3 has broken bcp in Trunk. One thing that has come up is default_name_check() which has been removed. bcp set that to a "do nothing" check since it deals only with files that already exist, so it really does not want to be told that a file name isn't portable! :-) The tests seem to pass OK without this, but should I be worried about this? I couldn't find a rationale for the change in the docs... Cheers, John.