[Bug c++/70182] c++filt fails to demangle _ZNSt17_Function_handlerIFSt4pairImjEjEZN5folly12addBenchmarkI3$_0EENSt9enable_ifIXeqsr5boost14function_types14function_arityIDTadsrT_onclEEE5valueLi2EEvE4typeEPKcSC_OS7_EUljE_E9_M_invokeERKSt9_Any_dataj

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70182

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
>Ian's go demangler and the libcxxabi demangler also are unable to demangle 
>these  symbols.

Because they are all the same code ...