[Bug c++/125770] New: reflection regression on members_of(global-namespace)

[ivan.lazaric.gcc at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125770

            Bug ID: 125770
           Summary: reflection regression on members_of(global-namespace)
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ivan.lazaric.gcc at gmail dot com
  Target Milestone: ---

```cpp
#include <meta>

consteval {
    members_of(^^::, std::meta::access_context::unchecked());
}
```

Compiler flags: "-std=c++26 -freflection"

This compiles on version 16.1, but doesn't on trunk
Godbolt: https://godbolt.org/z/qnqz7hfao

Compiler output on trunk:
```
reg.cpp:5:1:   in 'constexpr' expansion of '<lambda()> static()'
    5 | }
      | ^
reg.cpp:4:15: error: use of built-in parameter pack '__integer_pack' outside of
a template
    4 |     members_of(^^::, std::meta::access_context::unchecked());
      |     ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PROGRAM FAILED WITH EXIT CODE 1
```

IIUC this is since commit 05ea83ffd5409243902e1129e1e67ad7cff3afa6