https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99692
--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #4) > The __rvalue_ostream_type constraints are going away soon: > https://gcc.gnu.org/pipermail/gcc-patches/2021-March/566863.html N.B. that change is on gcc trunk now.
