[Bug c++/117578] cxa_demangle cannot deal with long names

[jengelh at inai dot de via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117578

--- Comment #1 from Jan Engelhardt <jengelh at inai dot de> ---
y.cpp: should change `char buf[1024]` to `char buf[1048576]`, but result stays
the same, it isn't getting decoded.