[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 #13 from Jason Merrill <jason at gcc dot gnu.org> ---
In the original testcase we do choose to do NRVO, but this fails

      /* Don't check copy-initialization for NRV in a coroutine ramp; we        
         implement this case as NRV, but it's specified as directly             
         initializing the return value from get_return_object().  */
      if (DECL_RAMP_FN (current_function_decl) && named_return_value_okay_p)
        converted = true;

because DECL_RAMP_FN is null in the ramp.

So then we try to do the conversion, which fails because LazyTask doesn't have
a move constructor (because it has a user-declared destructor).

So I think DECL_RAMP_P is the only fix we need.