boost::filesystem::absolute mixes generic and native format

[hajokirchhoff]

Under Windows:

absolute(wpath(L"test/filename.ext")).native()

returns something akin to

c:\somedir\test/filename.ext

The problem is that absolute uses the current working directory when no cwd is given and the cwd under windows uses backslash. wpath using forward slash is valid, but the resulting path uses both, back- and forward slash, which is invalid and cannot be passed to ::CreateFile for example.

absolute must verify that all parts use the same path delimiter.