[Bug c++/96256] New: Invalid consteval call not rejected

[johelegp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96256

            Bug ID: 96256
           Summary: Invalid consteval call not rejected
           Product: gcc
           Version: 11.0
               URL: https://godbolt.org/z/zeEY96
            Status: UNCONFIRMED
          Keywords: accepts-invalid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: johelegp at gmail dot com
                CC: johelegp at gmail dot com
  Target Milestone: ---

See https://godbolt.org/z/zeEY96.
```C++
struct X
{
    consteval X operator+() const { return {}; }
};
consteval void g(X) { }
void f()
{
    X x;
    +x;
    g(x);
}
```
This might generalize https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95593.