[Bug c++/71737] ICE following 2x pack expansion in non-pack with template alias

[pkeir at outlook dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71737

--- Comment #1 from Paul Keir <pkeir at outlook dot com> ---
Created attachment 38820
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38820&action=edit
Minimal testcase.