[Bug libstdc++/120561] std::weak_ptr cannot be converted to std::weak_ptr or std::weak_ptr, and std::weak_ptr cannot be converted to std::weak_ptr

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120561

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Backported as r14-11828-gd0c4f654354a7e for 14.4 and r13-9742-g6e8dcc0aa0ba5d
for 13.5