[Bug c++/92034] extern template declarations cannot have internal linkage (unnamed namespace)

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92034

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Only clang errors out.
ICC, GCC and MSVC all accept the code.