[Bug c++/85523] Add fix-it hint for missing return statement in assignment operators

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85523

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Created attachment 44017
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44017&action=edit
Proof-of-concept patch to add fix-it