[Bug c++/126620] New: Error on class declaration in template for in consteval block

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D126620

            Bug ID: 126620
           Summary: Error on class declaration in template for in
                    consteval block
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: eczbek.void at gmail dot com
  Target Milestone: ---

https://godbolt.org/z/Ee8co3qzW

```
consteval {
        template for (char _ : "") {
                struct S;
        }
}
```

```
<source>: In static member function '<lambda()> static':
<source>:3:24: sorry, unimplemented: local class in lambda in template
parameter list
    3 |                 struct S;
      |                        ^
```=