[Bug c++/123277] New: [16 Regression] [[maybe_unused]] does not silence Wunused-local-typedefs

[enrico.seiler+gccbugs at outlook dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123277

            Bug ID: 123277
           Summary: [16 Regression] [[maybe_unused]] does not silence
                    Wunused-local-typedefs
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: enrico.seiler+gccbugs at outlook dot com
  Target Milestone: ---

The following code

```
void A(auto B)
{
    using C [[maybe_unused]] = decltype(B);
}
```

generates

```
warning: typedef 'using C = decltype (B)' locally defined but not used
[-Wunused-local-typedefs]
```

Previous versions do not emit the warning.

https://godbolt.org/z/eo967EoTb