https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99333
Bug ID: 99333 Summary: std::filesystem::path().is_absolute() thinks UNC paths aren't absolute Product: gcc Version: 10.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: moritz at bunkus dot org Target Milestone: --- Created attachment 50280 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50280&action=edit test case Compiling with gcc 10.2.0 from the mxe cross compilation environment for Windows. The attached sample program says it all. It shows that std::filesystem::("\\server\share\file.txt").is_absolute() is false and turns std::filesystem::absolute("\\server\share\file.txt") into something like "C:\server\share\file.txt". boost::filesystem::path(…).is_aboslute(), on the other hand, considers UNC paths absolute & leaves them unmodified via boost::filesystem::absolute(…) The test program outputs the following: std::filesystem: original \\disky\mosu\existing_file.txt is_absolute 0 absolute "C:\\disky\\mosu\\existing_file.txt" boost::filesystem: original \\disky\mosu\existing_file.txt is_absolute 1 absolute "\\disky\mosu\existing_file.txt" Compile with something like: x86_64-w64-mingw32.static-g++ -std=c++17 \ -I/home/mosu/prog/video/mingw/cross/usr/x86_64-w64-mingw32.static/include \ -L/home/mosu/prog/video/mingw/cross/usr/x86_64-w64-mingw32.static/lib \ -o std_filesystem_unc_paths_vs_absolute.exe \ std_filesystem_unc_paths_vs_absolute.cpp \ -lboost_filesystem-mt-s-x64 -lboost_system-mt-s-x64