[Bug c++/107981] New: 'operator auto' has not been declared in base

[egor.pugin at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107981

            Bug ID: 107981
           Summary: 'operator auto' has not been declared in base
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: egor.pugin at gmail dot com
  Target Milestone: ---

struct a {
    operator auto() { return 1; }
};
struct b : a {
    using a::operator auto;
};

gives

<source>:5:23: error: 'operator auto' has not been declared in 'struct a'
    5 |     using a::operator auto;
      |                       ^~~~

Exerything is fine for clang/msvc.

https://godbolt.org/z/cTnxs97r6