[Bug c++/107981] '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

--- Comment #1 from Egor Pugin <egor.pugin at gmail dot com> ---
Also see following test cases.

===

ok for gcc

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

===

not ok for gcc&clang, ok for msvc

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

int main(){b v;int x = v;}

===