> > 18 nov. 2020 kl. 17:26 skrev René Berber via Cygwin <cygwin@cygwin.com>: > > > > On 11/18/2020 3:00 AM, Kristian Ivarsson via Cygwin wrote: > > > >>>> On 11/17/2020 9:15 AM, Kristian Ivarsson via Cygwin wrote: > >>> > >>>> The filesystem-library as a part of C++17 seems to have some > >>>> defects and flaws in the cygwin-package and pretty much every > >>>> lexical- and canonical operation works in mysterious ways (or not > >>>> at all) > >>> [snip] > >>> > >>> https://cygwin.com/cygwin-ug-net/using.html#pathnames-win32
[snip] > As stated earlier, it seems like using mingw g++/libstdc++ (from the > cygwin-package-manager) it seems like it works better, but then you can’t > mix with other posix/cygwin mechanism (that uses cygstdc++) without > breaking ODR (and probably some memory models etc as well) so maybe > someone do have some insightful info about this ? How “special” is > cygstdc++ (compared to mingw:s libstdc++) ? Could this be fixable in that > library (cygstdc++) ? I think the problem can be viewed in /usr/lib/gcc/x86_64-pc-cygwin/10/include/c++/bits/fs_path.h and ... #if defined(_WIN32) && !defined(__CYGWIN__) # define _GLIBCXX_FILESYSTEM_IS_WINDOWS 1 # include <algorithm> #endif ... that when build in CYGWIN will make the stdc++ think it is not on Windows (and I guess cygstdc++-6.dll will be built without _GLIBCXX_FILESYSTEM_IS_WINDOWS implicitly), thus, the std::filesystem-library will act as it is on a Posix-system, but it is not and thus it makes wrong assumptions It seems like the (ordinary) MinGW-shipping includes these directives (!defined(__CYGWIN__)) as well and my naive take on this is that it is a (the) mistake The underlaying filesystem IS Windows and NOT Posix, but my guess is that (some) Posix-system-calls and/or assuming Posix-style-paths are invoked when _GLIBCXX_FILESYSTEM_IS_WINDOWS is not set I guess the correct way would be to let _GLIBCXX_FILESYSTEM_IS_WINDOWS and maybe just have a #ifdef (__CYGWIN__) as an extra option ONLY when handling lexical stuff, i.e. it allows both Windows- and Posix-styles but the system calls should always be Windows calls (and I guess this would imply better performance as well to not need to walk through the whole Cygwin-posix-abstraction) I might be totally wrong, so does anyone have any take on this ? Best regards, Kristian > Best regards, > Kristian [snip] -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
