Hi Jonathan, On Fri, 11 Jun 2021 at 20:25, Jonathan Wakely via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > In C++23 there is a basic_string_view(Range&&) constructor, which is > constrained to take a range (specifically, a contiguous_range). When the > filesystem::path comparison operators call lhs.compare(rhs) the overload > taking a string_view is considered, which means checking whether path > satisfies the range concept. That satisfaction result changes depending > whether path::iterator is complete, which is ill-formed; no diagnostic > required. To avoid the problem, this change ensures that the overload > resolution is performed in a context where path::iterator is complete > and the range concept is satisfied. (The result of overload resolution > is always that the compare(const path&) overload is the best match, but > we still have to consider the compare(basic_string_view<value_type>) one > to decide if it even participates in overload resolution). > > For std::filesystem::path we can't define the comparison operators later > in the file, because they are hidden friends, so a new helper is > introduced that gets defined when everything else is complete. > > For std::experimental::filesystem::path we can just move the definitions > of the comparison operators later in the file. > > Signed-off-by: Jonathan Wakely <jwak...@redhat.com> > > libstdc++-v3/ChangeLog: > > * include/bits/fs_path.h (operator==, operator<=>): Use new > _S_compare function. > (path::_S_compare): New function to call path::compare in a > context where path::iterator is complete. > * include/experimental/bits/fs_path.h (operator<, operator==): > Define after path::iterator is complete. > * testsuite/27_io/filesystem/path/native/conv_c++23.cc: New > test. > * testsuite/experimental/filesystem/path/native/conv_c++23.cc: > New test. > > Tested powerpc64le-linux. Committed to trunk. > > This also needs to be backported to gcc-11 where the string_view > constructor is present for C++23 mode. >
The new test experimental/filesystem/path/native/conv_c++23.cc fails on arm-eabi and aarch64-elf: /libstdc++-v3/testsuite/experimental/filesystem/path/native/conv_c++23.cc:4: fatal error: experimental/filesystem: No such file or directory (both trunk and gcc-11) I guess that's easy to fix? :-) Thanks, Christophe
