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From: "moritz at bunkus dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/99333] New: std::filesystem::path().is_absolute()
 thinks UNC paths aren't absolute
Date: Mon, 01 Mar 2021 21:45:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99333

            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=3D50280&action=3Dedit
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 tur=
ns
std::filesystem::absolute("\\server\share\file.txt") into something like
"C:\server\share\file.txt".

boost::filesystem::path(=E2=80=A6).is_aboslute(), on the other hand, consid=
ers UNC
paths absolute & leaves them unmodified via boost::filesystem::absolute(=E2=
=80=A6)

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=3Dc++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=