John Maddock:
See http://svn.boost.org/svn/boost/sandbox/filesystem-v3/libs/filesystem/doc/v3_... for a fuller description of the prototype and links to the prototype implementation.
locale( "" ) is not correct on Mac OS X, where the API always takes UTF-8 char* and the filesystem uses wchar_t internally (AFAIK).
This is irrelevant from a practical point of view, but the standard requires that "" be recognised as a valid locale:
"" is a valid locale, but it is not correct to use it for path conversions. Paths on Mac OS X are always UTF-8 (when viewed through the POSIX API). (They are also normalized in a variation of form D, but this can probably be ignored for our purposes.) Disclaimer: this is what I read in Apple's docs. I have never used Mac OS X myself. :-)