[Bug c++/124096] New: [reflection] bit_cast with consteval-only types should be rejected

[mpolacek at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124096

            Bug ID: 124096
           Summary: [reflection] bit_cast with consteval-only types should
                    be rejected
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mpolacek at gcc dot gnu.org
  Target Milestone: ---

```
#include <bit>

consteval void f() {
    (void) std::bit_cast<long long>(^^int);
}
```

is ill-formed per https://eel.is/c++draft/bit.cast#2 but we accept it.