[Bug c++/64073] Explicit duplicate template instantiation not reported as error when using 'using'

[eugene at hutorny dot in.ua]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64073

--- Comment #1 from Eugene <eugene at hutorny dot in.ua> ---
Created attachment 34117
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34117&action=edit
Code sample illustrating the problem