[Bug libstdc++/93562] [8/9/10 Regression] unique_ptr::swap incorrectly uses generic std::swap

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93562

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|9.2.0                       |6.5.0
   Target Milestone|10.0                        |8.4
            Summary|[10 Regression]             |[8/9/10 Regression]
                   |unique_ptr::swap requires   |unique_ptr::swap
                   |complete type               |incorrectly uses generic
                   |                            |std::swap
      Known to fail|                            |7.5.0, 8.3.0, 9.2.0

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Summary and other fields adjusted to reflect the root cause: using the generic
std::swap on the __uniq_ptr_impl object performs a move-construction and
move-assignments, but should only perform swaps (possibly finding a custom swap
via ADL).

Thanks to Billy Baker for finding this bug.