[Bug libstdc++/65762] --with-default-libstdcxx-abi=c++11 is silently ignored when --disable-libstdcxx-dual-abi is used

[iains at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65762

--- Comment #1 from Iain Sandoe <iains at gcc dot gnu.org> ---
so, FAOD, that means that 
versioned namespace => disables dual ABI 
                    => forces the old string impl?

What's the blocker to making it work?
(just time - or ABI issues?)