[Bug c++/120453] [16 regression] qcoro fails to build its tests (error: use of deleted function ... is implicitly deleted because the default definition would be ill-formed) since r16-773-ge06555a40c051d

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120453

--- Comment #15 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to Iain Sandoe from comment #14)
>  * If we add the non-coroutine simulation of the ramp, then clang-20 also
> complains - but with a different diagnostic:
> 
> "<source>:97:10: error: call to implicitly-deleted copy constructor of
> 'LazyTask<int>'
>    97 |   return Gro;

So they complain about the deleted copy constructor rather than the deleted
move constructor.  That's probably this bit in joust:

  /* Prefer a non-deleted function over an implicitly deleted move              
     constructor or assignment operator.  This differs slightly from the        
     wording for issue 1402 (which says the move op is ignored by overload      
     resolution), but this way produces better error messages.  */