https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119687
--- Comment #2 from Sam James <sjames at gcc dot gnu.org> ---
Invalid reduction:
```
class QDebug {};
struct QFlags {};
namespace QtPrivate {
template <typename> class QFlagsStorage;
template <typename Enum> struct QFlagsStorageHelper : {
using QFlagsStorage<Enum>::QFlagsStorage;
protected:
QFlagsStorageHelper();
};
template <typename Enum> struct QFlags : public QtPrivate::QFlagsStorageHelper
{
using Base = QtPrivate::QFlagsStorageHelper<Enum>;
using Base::Base;
};
template <typename T> void operator<<(QDebug debug, int flag) {
debug << QFlags();
}
} // namespace QtPrivate
```
