[Bug c++/66067] [6 Regression] tree check ICE: accessed elt 1 of tree_vec with 0 elts in write_template_args, at cp/mangle.c:2574

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66067

--- Comment #15 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to Victoria from comment #14)
> issue not seen in GCC 5.x branch, is possible to backport the patch?

I don't understand.  If the issue is not seen, why backport?