[Bug c++/77379] New: incorrect mangling for non-virtual adjustor thunk (missing abi tag)

["richard-gccbugzilla at metafoo dot co.uk" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77379

            Bug ID: 77379
           Summary: incorrect mangling for non-virtual adjustor thunk
                    (missing abi tag)
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: richard-gccbugzilla at metafoo dot co.uk
  Target Milestone: ---

GCC does not emit ABI tags from a function return type when mangling an
adjustor thunk (see example in https://llvm.org/bugs/show_bug.cgi?id=28997).

If this is intentional, and there's some good reason to omit the abi_tag
mangling here, let us know and we'll suppress them from Clang too.