https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87150
--- Comment #11 from Jason Merrill <jason at gcc dot gnu.org> --- (In reply to Stephan Bergmann from comment #9) > (In reply to Marek Polacek from comment #8) > > It appears that the sentiment is that this testcase should actually be > > valid > > Do you have a reference for that? The reason for this not to be valid, > presented at the bottom of > <http://lists.llvm.org/pipermail/cfe-dev/2018-August/059190.html> "Re: > [cfe-dev] return lvalue move instead of copy?" looks rather convincing to me. (Namely, slicing by move leaving the object in a partially-moved state that might not maintain invariants.) That's a good point. I guess the rule we're looking for will still require that the returned object being treated as an xvalue be bound to some rvalue reference to the whole object, rather than a base subobject. So Marek, please go ahead and apply your patch after all. And similarly, maybe refine your 87109 patch to only reject the conversion function if it comes from a base class.
