[Bug c++/117446] New: Rejects valid code on template parameter packs not expanded with '...'

[suyuchang at whu dot edu.cn via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117446

            Bug ID: 117446
           Summary: Rejects valid code on template parameter packs not
                    expanded with '...'
           Product: gcc
           Version: 14.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: suyuchang at whu dot edu.cn
  Target Milestone: ---

Input：

template < typename... X1 > struct [[ X1 ]] final { } ;


Output：
<source>:1:45: error: parameter packs not expanded with '...':
    1 | template < typename... X1 > struct [[ X1 ]] final { } ;
      |                                             ^~~~~
<source>:1:45: note:         'X1'
Compiler returned: 1

It is rejected by Clang, but accepted by GCC.