1e690757d3
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 <jwakely@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.