[Bug c++/123917] New: GCC incorrectly accepts a requires statement terminating with an ellipsis.

[mingdeng7254 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123917

            Bug ID: 123917
           Summary: GCC incorrectly accepts a requires statement
                    terminating with an ellipsis.
           Product: gcc
           Version: 15.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mingdeng7254 at gmail dot com
  Target Milestone: ---

The following code:

```cpp
template <typename T>
concept C = requires(T t, ...) { t; };
```

is accepted by GCC but shall be error according to the C++ standard
([expr.prim.req.general#4](https://eel.is/c++draft/expr.prim.req.general#4)). 

A Godbolt link to the test case is available here:
https://godbolt.org/z/47Y7GKGTG