[Bug c++/99086] including and defaulting spaceship operator causes compiler segfault

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99086

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
           Keywords|                            |ice-on-invalid-code
      Known to work|                            |11.0
      Known to fail|                            |10.2.1
   Last reconfirmed|                            |2021-02-14
                 CC|                            |jason at gcc dot gnu.org

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to crillion from comment #0)
> #include <iterator>
> 
> class value_wrapper
> {
>       public :
>               
>               bool operator<=>(const value_wrapper& rhs) const = default;

This is a bug, the spaceship operator has to return one of
std::strong_ordering, std::weak_ordering or std::partial_ordering.

GCC's crash on the invalid code has already been fixed in r11-5866:

    c++: Fix defaulted <=> fallback to < and == [PR96299]

I don't know if there are plans to backport that.