Bring templated base class conversion operator into derived scope

Question

I have a base class that defines a constrained templated conversion operator

struct base {
    template 

        

Answer 1

I would say it is not possible. and even if it was, your derived operator would hide base one as template argument is not part according to namespace.udecl#15.sentence-1:

When a using-declarator brings declarations from a base class into a derived class, member functions and member function templates in the derived class override and/or hide member functions and member function templates with the same name, parameter-type-list, cv-qualification, and ref-qualifier (if any) in a base class (rather than conflicting)

Unfortunately, template parameter doesn't count and both conversion operator has empty parameter-type-list, are const and no ref-qualifier.