[Bug libstdc++/106201] filesystem::directory_iterator is a borrowable range?

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106201

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I'm planning to use this workaround for gcc-11 and gcc-12:

--- a/libstdc++-v3/include/bits/fs_path.h
+++ b/libstdc++-v3/include/bits/fs_path.h
@@ -737,7 +737,14 @@ namespace __detail
   /// @{
   /// @relates std::filesystem::path

+#if __cpp_concepts >= 201907L
+  // Workaround for PR libstdc++/106201
+  inline void
+  swap(same_as<path> auto& __lhs, same_as<path> auto& __rhs) noexcept
+  { __lhs.swap(__rhs); }
+#else
   inline void swap(path& __lhs, path& __rhs) noexcept { __lhs.swap(__rhs); }
+#endif

   size_t hash_value(const path& __p) noexcept;

This will prevent that swap overload from being a candidate for swapping
counted_iterator<filesystem::directory_iterator>, so we won't check for
conversion to path& and hit the constraint recursion.