[Bug c++/77950] GCC produces un-demanglable symbols with [] (auto&) { ... } lambdas in templates

[ian at airs dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77950

--- Comment #2 from Ian Lance Taylor <ian at airs dot com> ---
Just a note that my Go demangler does demangle this symbol now, producing

ossia::vec_merger_impl<2>::operator()<eggs::variants::variant<ossia::strong_value<ossia::speed_ratio<std::ratio<1l,
1l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<16093440l,
36000000l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<1000l, 3600l>
> >, ossia::strong_value<ossia::speed_ratio<std::ratio<1852l, 3600l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 10000l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 36000000l> > > >
>(eggs::variants::variant<ossia::strong_value<ossia::speed_ratio<std::ratio<1l,
1l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<16093440l,
36000000l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<1000l, 3600l>
> >, ossia::strong_value<ossia::speed_ratio<std::ratio<1852l, 3600l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 10000l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 36000000l> > > >
const&)::{lambda(auto:1&)#1}&&
eggs::variants::detail::forward<ossia::vec_merger_impl<2>::operator()<eggs::variants::variant<ossia::strong_value<ossia::speed_ratio<std::ratio<1l,
1l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<16093440l,
36000000l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<1000l, 3600l>
> >, ossia::strong_value<ossia::speed_ratio<std::ratio<1852l, 3600l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 10000l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 36000000l> > > >
>(eggs::variants::variant<ossia::strong_value<ossia::speed_ratio<std::ratio<1l,
1l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<16093440l,
36000000l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<1000l, 3600l>
> >, ossia::strong_value<ossia::speed_ratio<std::ratio<1852l, 3600l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 10000l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 36000000l> > > >
const&)::{lambda(auto:1&)#1}&&>(std::remove_reference<ossia::vec_merger_impl<2>::operator()<eggs::variants::variant<ossia::strong_value<ossia::speed_ratio<std::ratio<1l,
1l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<16093440l,
36000000l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<1000l, 3600l>
> >, ossia::strong_value<ossia::speed_ratio<std::ratio<1852l, 3600l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 10000l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 36000000l> > > >
>(eggs::variants::variant<ossia::strong_value<ossia::speed_ratio<std::ratio<1l,
1l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<16093440l,
36000000l> > >, ossia::strong_value<ossia::speed_ratio<std::ratio<1000l, 3600l>
> >, ossia::strong_value<ossia::speed_ratio<std::ratio<1852l, 3600l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 10000l> > >,
ossia::strong_value<ossia::speed_ratio<std::ratio<3048l, 36000000l> > > >
const&)::{lambda(auto:1&)#1}&&>::type&)